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Saturday, November 23, 2024

Pantheism

From Wikipedia, the free encyclopedia
 
Pantheism is the philosophical and religious belief that reality, the universe, and nature are identical to divinity or a supreme entity. The physical universe is thus understood as an immanent deity, still expanding and creating, which has existed since the beginning of time. The term pantheist designates one who holds both that everything constitutes a unity and that this unity is divine, consisting of an all-encompassing, manifested god or goddess. All astronomical objects are thence viewed as parts of a sole deity.

Another definition of pantheism is the worship of all gods of every religion. But this is more precisely termed omnism. Pantheist belief does not recognize a distinct personal god, anthropomorphic or otherwise, but instead characterizes a broad range of doctrines differing in forms of relationships between reality and divinity. Pantheistic concepts date back thousands of years, and pantheistic elements have been identified in various religious traditions. The term pantheism was coined by mathematician Joseph Raphson in 1697 and since then, it has been used to describe the beliefs of a variety of people and organizations.

Pantheism was popularized in Western culture as a theology and philosophy based on the work of the 17th-century philosopher Baruch Spinoza, in particular, his book Ethics. A pantheistic stance was also taken in the 16th century by philosopher and cosmologist Giordano Bruno.

In the East, Advaita Vedanta, a school of Hindu philosophy is thought to be similar to pantheism in Western philosophy. The early Taoism of Laozi and Zhuangzi is also sometimes considered pantheistic, although it could be more similar to panentheism. Cheondoism, which arose in the Joseon Dynasty of Korea, and Won Buddhism are also considered pantheistic.

Etymology

Pantheism derives from the Greek word πᾶν pan (meaning "all, of everything") and θεός theos (meaning "god, divine"). The first known combination of these roots appears in Latin, in Joseph Raphson's 1697 book De Spatio Reali seu Ente Infinito, where he refers to "pantheismus". It was subsequently translated into English as "pantheism" in 1702.

Definitions

Pantheists believe that the universe itself and everything in it forms a single, all-encompassing deity.

There are numerous definitions of pantheism, including:

  • a theological and philosophical position which identifies God with the universe, or regards the universe as a manifestation of God;
  • the belief that everything is part of an all-encompassing, immanent God, and that all forms of reality may then be considered either modes of that Being, or identical with it; and
  • a non-religious philosophical position maintaining that the Universe (in the sense of the totality of all existence) and God are identical.

History

Pre-modern times

Early traces of pantheist thought can be found within animistic beliefs and tribal religions throughout the world as an expression of unity with the divine, specifically in beliefs that have no central polytheist or monotheist personas. Hellenistic theology makes early recorded reference to pantheism within the ancient Greek religion of Orphism, where pan (the all) is made cognate with the creator God Phanes (symbolizing the universe), and with Zeus, after the swallowing of Phanes.

Pantheistic tendencies existed in a number of Gnostic groups, with pantheistic thought appearing throughout the Middle Ages. These included the beliefs of mystics such as Ortlieb of Strasbourg, David of Dinant, Amalric of Bena, and Eckhart.

The Catholic Church has long regarded pantheistic ideas as heresy. Sebastian Franck was considered an early Pantheist. Giordano Bruno, an Italian friar who evangelized about a transcendent and infinite God, was burned at the stake in 1600 by the Roman Inquisition. He has since become known as a celebrated pantheist and martyr of science.

The Hindu philosophy of Advaita Vedanta is thought to be similar to pantheism. The term Advaita (literally "non-secondness", but usually rendered as "nondualism", and often equated with monism) refers to the idea that Brahman alone is ultimately real, while the transient phenomenal world is an illusory appearance (maya) of Brahman. In this view, jivatman, the experiencing self, is ultimately non-different ("na aparah") from Ātman-Brahman, the highest Self or Reality. The jivatman or individual self is a mere reflection or limitation of singular Ātman in a multitude of apparent individual bodies.

Baruch Spinoza

The philosophy of Baruch Spinoza is often regarded as pantheism.

In the West, pantheism was formalized as a separate theology and philosophy based on the work of the 17th-century philosopher Baruch Spinoza. Spinoza was a Dutch philosopher of Portuguese descent raised in the Sephardi Jewish community in Amsterdam. He developed highly controversial ideas regarding the authenticity of the Hebrew Bible and the nature of the Divine, and was effectively excluded from Jewish society at age 23, when the local synagogue issued a herem against him. A number of his books were published posthumously, and shortly thereafter included in the Catholic Church's Index of Forbidden Books.

In the posthumous Ethics, he opposed René Descartes' famous mind–body dualism, the theory that the body and spirit are separate. Spinoza held the monist view that the two are the same, and monism is a fundamental part of his philosophy. He was described as a "God-intoxicated man," and used the word God to describe the unity of all substance. This view influenced philosophers such as Georg Wilhelm Friedrich Hegel, who said, "You are either a Spinozist or not a philosopher at all." Spinoza earned praise as one of the great rationalists of 17th-century philosophy and one of Western philosophy's most important thinkers. Although the term "pantheism" was not coined until after his death, he is regarded as the most celebrated advocate of the concept. Ethics was the major source from which Western pantheism spread.

18th century

The first known use of the term "pantheism" was in Latin ("pantheismus") by the English mathematician Joseph Raphson in his work De Spatio Reali seu Ente Infinito, published in 1697. Raphson begins with a distinction between atheistic "panhylists" (from the Greek roots pan, "all", and hyle, "matter"), who believe everything is matter, and Spinozan "pantheists" who believe in "a certain universal substance, material as well as intelligence, that fashions all things that exist out of its own essence." Raphson thought that the universe was immeasurable in respect to a human's capacity of understanding, and believed that humans would never be able to comprehend it. He referred to the pantheism of the Ancient Egyptians, Persians, Syrians, Assyrians, Greek, Indians, and Jewish Kabbalists, specifically referring to Spinoza.

The term was first used in English by a translation of Raphson's work in 1702. It was later used and popularized by Irish writer John Toland in his work of 1705 Socinianism Truly Stated, by a Pantheist. Toland was influenced by both Spinoza and Bruno, and had read Joseph Raphson's De Spatio Reali, referring to it as "the ingenious Mr. Ralphson's (sic) Book of Real Space". Like Raphson, he used the terms "pantheist" and "Spinozist" interchangeably. In 1720 he wrote the Pantheisticon: or The Form of Celebrating the Socratic-Society in Latin, envisioning a pantheist society that believed, "All things in the world are one, and one is all in all things ... what is all in all things is God, eternal and immense, neither born nor ever to perish." He clarified his idea of pantheism in a letter to Gottfried Leibniz in 1710 when he referred to "the pantheistic opinion of those who believe in no other eternal being but the universe".

In the mid-eighteenth century, the English theologian Daniel Waterland defined pantheism this way: "It supposes God and nature, or God and the whole universe, to be one and the same substance—one universal being; insomuch that men's souls are only modifications of the divine substance." In the early nineteenth century, the German theologian Julius Wegscheider defined pantheism as the belief that God and the world established by God are one and the same.

Between 1785–89, a controversy about Spinoza's philosophy arose between the German philosophers Friedrich Heinrich Jacobi (a critic) and Moses Mendelssohn (a defender). Known in German as the Pantheismusstreit (pantheism controversy), it helped spread pantheism to many German thinkers.

19th century

Growing influence

During the beginning of the 19th century, pantheism was the viewpoint of many leading writers and philosophers, attracting figures such as William Wordsworth and Samuel Coleridge in Britain; Johann Gottlieb Fichte, Schelling and Hegel in Germany; Knut Hamsun in Norway; and Walt Whitman, Ralph Waldo Emerson and Henry David Thoreau in the United States. Seen as a growing threat by the Vatican, in 1864 it was formally condemned by Pope Pius IX in the Syllabus of Errors.

A letter written in 1886 by William Herndon, Abraham Lincoln's law partner, was sold at auction for US$30,000 in 2011. In it, Herndon writes of the U.S. President's evolving religious views, which included pantheism.

"Mr. Lincoln's religion is too well known to me to allow of even a shadow of a doubt; he is or was a Theist and a Rationalist, denying all extraordinary – supernatural inspiration or revelation. At one time in his life, to say the least, he was an elevated Pantheist, doubting the immortality of the soul as the Christian world understands that term. He believed that the soul lost its identity and was immortal as a force. Subsequent to this he rose to the belief of a God, and this is all the change he ever underwent."

The subject is understandably controversial, but the content of the letter is consistent with Lincoln's fairly lukewarm approach to organized religion.

Comparison with non-Christian religions

Some 19th-century theologians thought that various pre-Christian religions and philosophies were pantheistic. They thought Pantheism was similar to the ancient Hinduism philosophy of Advaita (non-dualism).

19th-century European theologians also considered Ancient Egyptian religion to contain pantheistic elements and pointed to Egyptian philosophy as a source of Greek Pantheism. The latter included some of the Presocratics, such as Heraclitus and Anaximander. The Stoics were pantheists, beginning with Zeno of Citium and culminating in the emperor-philosopher Marcus Aurelius. During the pre-Christian Roman Empire, Stoicism was one of the three dominant schools of philosophy, along with Epicureanism and Neoplatonism. The early Taoism of Laozi and Zhuangzi is also sometimes considered pantheistic, although it could be more similar to panentheism.

Cheondoism, which arose in the Joseon Dynasty of Korea, and Won Buddhism are also considered pantheistic. The Realist Society of Canada believes that the consciousness of the self-aware universe is reality, which is an alternative view of Pantheism.

20th century

In the late 20th century, some declared that pantheism was an underlying theology of Neopaganism, and pantheists began forming organizations devoted specifically to pantheism and treating it as a separate religion.

Levi Ponce's Luminaries of Pantheism mural in Venice, California, for The Paradise Project

21st century

Albert Einstein is considered a pantheist by some commentators.

Dorion Sagan, son of scientist and science communicator Carl Sagan, published the 2007 book Dazzle Gradually: Reflections on the Nature of Nature, co-written with his mother Lynn Margulis. In the chapter "Truth of My Father", Sagan writes that his "father believed in the God of Spinoza and Einstein, God not behind nature, but as nature, equivalent to it."

In 2009, pantheism was mentioned in a Papal encyclical and in a statement on New Year's Day, 2010, criticizing pantheism for denying the superiority of humans over nature and seeing the source of man's salvation in nature.

In 2015, The Paradise Project, an organization "dedicated to celebrating and spreading awareness about pantheism," commissioned Los Angeles muralist Levi Ponce to paint the 75-foot mural in Venice, California, near the organization's offices. The mural depicts Albert Einstein, Alan Watts, Baruch Spinoza, Terence McKenna, Carl Jung, Carl Sagan, Emily Dickinson, Nikola Tesla, Friedrich Nietzsche, Ralph Waldo Emerson, W.E.B. Du Bois, Henry David Thoreau, Elizabeth Cady Stanton, Rumi, Adi Shankara, and Laozi.

Categorizations

There are multiple varieties of pantheism and various systems of classifying them relying upon one or more spectra or in discrete categories.

Degree of determinism

The philosopher Charles Hartshorne used the term Classical Pantheism to describe the deterministic philosophies of Baruch Spinoza, the Stoics, and other like-minded figures. Pantheism (All-is-God) is often associated with monism (All-is-One) and some have suggested that it logically implies determinism (All-is-Now). Albert Einstein explained theological determinism by stating, "the past, present, and future are an 'illusion'". This form of pantheism has been referred to as "extreme monism", in which – in the words of one commentator – "God decides or determines everything, including our supposed decisions." Other examples of determinism-inclined pantheisms include those of Ralph Waldo Emerson, and Hegel.

However, some have argued against treating every meaning of "unity" as an aspect of pantheism, and there exist versions of pantheism that regard determinism as an inaccurate or incomplete view of nature. Examples include the beliefs of John Scotus Eriugena, Friedrich Wilhelm Joseph Schelling and William James.

Degree of belief

It may also be possible to distinguish two types of pantheism, one being more religious and the other being more philosophical. The Columbia Encyclopedia writes of the distinction:

"If the pantheist starts with the belief that the one great reality, eternal and infinite, is God, he sees everything finite and temporal as but some part of God. There is nothing separate or distinct from God, for God is the universe. If, on the other hand, the conception taken as the foundation of the system is that the great inclusive unity is the world itself, or the universe, God is swallowed up in that unity, which may be designated nature."

Form of monism

A diagram with neutral monism compared to Cartesian dualism, physicalism and idealism

Philosophers and theologians have often suggested that pantheism implies monism.

For the Aztecs teotl was the metaphysical omnipresence creating the cosmos and all its contents from within itself as well as out of itself. This is conceptualized in a kind of monistic pantheism as manifest in the supreme god Ometeotl, as well as a large pantheon of lesser gods and idealizations of natural phenomena.

Other

In 1896, J. H. Worman, a theologian, identified seven categories of pantheism: Mechanical or materialistic (God the mechanical unity of existence); Ontological (fundamental unity, Spinoza); Dynamic; Psychical (God is the soul of the world); Ethical (God is the universal moral order, Fichte); Logical (Hegel); and Pure (absorption of God into nature, which Worman equates with atheism).

In 1984, Paul D. Feinberg, professor of biblical and systematic theology at Trinity Evangelical Divinity School, also identified seven: Hylozoistic; Immanentistic; Absolutistic monistic; Relativistic monistic; Acosmic; Identity of opposites; and Neoplatonic or emanationistic.

Demographics

Prevalence

According to censuses of 2011, the UK was the country with the most Pantheists. As of 2011, about 1,000 Canadians identified their religion as "Pantheist", representing 0.003% of the population. By 2021, the number of Canadian pantheists had risen to 1,855 (0.005%). In Ireland, Pantheism rose from 202 in 1991, to 1106 in 2002, to 1,691 in 2006, 1,940 in 2011. In New Zealand, there was exactly one pantheist man in 1901. By 1906, the number of pantheists in New Zealand had septupled to 7 (6 male, 1 female). This number had further risen to 366 by 2006.

Age, ethnicity, and gender

The 2021 Canadian census showed that pantheists were somewhat more likely to be in their 20s and 30s compared to the general population. People under 15 were about four times less likely to be pantheist than the general population.

The 2021 Canadian census also showed that pantheists were less likely to be part of a recognized minority group compared to the general population, with 90.3% of pantheists not being part of any minority group (compared to 73.5% of the general population). The census did not register any pantheists who were Arab, Southeast Asian, West Asian, Korean, or Japanese.

In Canada (2011), there was no gender difference in regards to pantheism. However, in Ireland (2011), pantheists were slightly more likely to be female (1074 pantheists, 0.046% of women) than male (866 pantheists, 0.038% of men). In contrast, Canada (2021) showed pantheists to be slightly more likely to be male, with men representing 51.5% of pantheists.

Comparison of pantheists in Canada against the general population (2021)

General population Pantheists
Total population 36,328,480 1,855
Gender Male 17,937,165 (49.4%) 955 (51.5%)
Female 18,391,315 (50.6%) 895 (48.2%)
Age 0 to 14 5,992,555 (16.5%) 75 (4%)
15 to 19 2,003,200 (5.5%) 40 (2%)
20 to 24 2,177,860 (6%) 125 (6.7%)
25 to 34 4,898,625 (13.5%) 405 (21.8%)
35 to 44 4,872,425 (13.4%) 380 (20.5%)
45 to 54 4,634,850 (12.8%) 245 (13.2%)
55 to 64 5,162,365 (14.2%) 245 13.2%)
65 and over 6,586,600 (18.1%) 325 (17.5%)
Ethnicity Non-minority 26,689,275 (73.5%) 1,675 (90.3%)
South Asian 2,571,400 (7%) 20 (1.1%)
Chinese 1,715,770 (4.7%) 45 (2.4%)
Black 1,547,870 (4.3%) 45 (2.4%)
Filipino 957,355 (2.6%) 10 (0.5%)
Arab 694,015 (1.9%) 0 (0%)
Latin American 580,235 (1.6%) 25 (1.3%)
Southeast Asian 390,340 (1.1%) 0 (0%)
West Asian 360,495 (1%) 0 (0%)
Korean 218,140 (0.6%) 0 (0%)
Japanese 98,890 (0.3%) 0 (0%)
Visible minority, n.i.e. 172,885 (0.5%) 0 (0%)
Multiple visible minorities 331,805 (0.9%) 15 (0.8%)
Canadian pantheist population by percentage (2011 National Household Survey)

Nature worship or nature mysticism is often conflated and confused with pantheism. It is pointed out by at least one expert, Harold Wood, founder of the Universal Pantheist Society, that in pantheist philosophy Spinoza's identification of God with nature is very different from a recent idea of a self identifying pantheist with environmental ethical concerns. His use of the word nature to describe his worldview may be vastly different from the "nature" of modern sciences. He and other nature mystics who also identify as pantheists use "nature" to refer to the limited natural environment (as opposed to man-made built environment). This use of "nature" is different from the broader use from Spinoza and other pantheists describing natural laws and the overall phenomena of the physical world. Nature mysticism may be compatible with pantheism but it may also be compatible with theism and other views. Pantheism has also been involved in animal worship especially in primal religions.

Nontheism is an umbrella term which has been used to refer to a variety of religions not fitting traditional theism, and under which pantheism has been included.

Panentheism (from Greek πᾶν (pân) "all"; ἐν (en) "in"; and θεός (theós) "God"; "all-in-God") was formally coined in Germany in the 19th century in an attempt to offer a philosophical synthesis between traditional theism and pantheism, stating that God is substantially omnipresent in the physical universe but also exists "apart from" or "beyond" it as its Creator and Sustainer. Thus panentheism separates itself from pantheism, positing the extra claim that God exists above and beyond the world as we know it. The line between pantheism and panentheism can be blurred depending on varying definitions of God, so there have been disagreements when assigning particular notable figures to pantheism or panentheism.

Pandeism is another word derived from pantheism, and is characterized as a combination of reconcilable elements of pantheism and deism. It assumes a Creator-deity that is at some point distinct from the universe and then transforms into it, resulting in a universe similar to the pantheistic one in present essence, but differing in origin.

Panpsychism is the philosophical view that consciousness, mind, or soul is a universal feature of all things. Some pantheists also subscribe to the distinct philosophical views hylozoism (or panvitalism), the view that everything is alive, and its close neighbor animism, the view that everything has a soul or spirit.

Pantheism in religion

Traditional religions

Many traditional and folk religions including African traditional religions and Native American religions can be seen as pantheistic, or a mixture of pantheism and other doctrines such as polytheism and animism. According to pantheists, there are elements of pantheism in some forms of Christianity.

Ideas resembling pantheism existed in Eastern religions before the 18th century (notably Hinduism, Confucianism, and Taoism). Although there is no evidence that these influenced Spinoza's work, there is such evidence regarding other contemporary philosophers, such as Leibniz, and later Voltaire. In the case of Hinduism, pantheistic views exist alongside panentheistic, polytheistic, monotheistic, and atheistic ones.

Spirituality and new religious movements

Pantheism is popular in modern spirituality and new religious movements, such as Neopaganism and Theosophy. Two organizations that specify the word pantheism in their title formed in the last quarter of the 20th century. The Universal Pantheist Society, open to all varieties of pantheists and supportive of environmental causes, was founded in 1975. The World Pantheist Movement is headed by Paul Harrison, an environmentalist, writer and a former vice president of the Universal Pantheist Society, from which he resigned in 1996. The World Pantheist Movement was incorporated in 1999 to focus exclusively on promoting naturalistic pantheism – a strict metaphysical naturalistic version of pantheism, considered by some a form of religious naturalism. It has been described as an example of "dark green religion" with a focus on environmental ethics.

Meiotic drive

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Meiotic_drive

Meiotic drive is a type of intragenomic conflict, whereby one or more loci within a genome will affect a manipulation of the meiotic process in such a way as to favor the transmission of one or more alleles over another, regardless of its phenotypic expression. More simply, meiotic drive is when one copy of a gene is passed on to offspring more than the expected 50% of the time. According to Buckler et al., "Meiotic drive is the subversion of meiosis so that particular genes are preferentially transmitted to the progeny. Meiotic drive generally causes the preferential segregation of small regions of the genome".

Meiotic drive in plants

The first report of meiotic drive came from Marcus Rhoades who in 1942 observed a violation of Mendelian segregation ratios for the R locus - a gene controlling the production of the purple pigment anthocyanin in maize kernels - in a maize line carrying abnormal chromosome 10 (Ab10). Ab10 differs from the normal chromosome 10 by the presence of a 150-base pair heterochromatic region called 'knob', which functions as a centromere during division (hence called 'neocentromere') and moves to the spindle poles faster than the centromeres during meiosis I and II. The mechanism for this was later found to involve the activity of a kinesin-14 gene called Kinesin driver (Kindr). Kindr protein is a functional minus-end directed motor, displaying quicker minus-end directed motility than an endogenous kinesin-14, such as Kin11. As a result Kindr outperforms the endogenous kinesins, pulling the 150 bp knobs to the poles faster than the centromeres and causing Ab10 to be preferentially inherited during meiosis 

Meiotic drive in animals

The unequal inheritance of gametes has been observed since the 1950s, in contrast to Gregor Mendel's First and Second Laws (the law of segregation and the law of independent assortment), which dictate that there is a random chance of each allele being passed on to offspring. Examples of selfish drive genes in animals have primarily been found in rodents and flies. These drive systems could play important roles in the process of speciation. For instance, the proposal that hybrid sterility (Haldane's rule) may arise from the divergent evolution of sex chromosome drivers and their suppressors.

Meiotic drive in mice

Early observations of mouse t-haplotypes by Mary Lyon described numerous genetic loci on chromosome 17 that suppress X-chromosome sex ratio distortion. If a driver is left unchecked, this may lead to population extinction as the population would fix for the driver (e.g. a selfish X chromosome), removing the Y chromosome (and therefore males) from the population. The idea that meiotic drivers and their suppressors may govern speciation is supported by observations that mouse Y chromosomes lacking certain genetic loci produce female-biased offspring, implying these loci encode suppressors of drive. Moreover, matings of certain mouse strains used in research results in unequal offspring ratios. One gene responsible for sex ratio distortion in mice is r2d2 (r2d2 – responder to meiotic drive 2), which predicts which strains of mice can successfully breed without offspring sex ratio distortion.

Meiotic drive in flies

A stalk-eyed fly

Selfish chromosomes of stalk-eyed flies have had ecological consequences. Driving X chromosomes lead to reductions in male fecundity and mating success, leading to frequency dependent selection maintaining both the driving alleles and wild-type alleles.

Multiple species of fruit fly are known to have driving X chromosomes, of which the best-characterized are found in Drosophila simulans. Three independent driving X chromosomes are known in D. simulans, called Paris, Durham, and Winters. In Paris, the driving gene encodes a DNA modelling protein ("heterochromatin protein 1 D2" or HP1D2), where the allele of the driving copy fails to prepare the male Y chromosome for meiosis. In Winters, the gene responsible ("Distorter on the X" or Dox) has been identified, though the mechanism by which it acts is still unknown. The strong selective pressure imposed by these driving X chromosomes has given rise to suppressors of drive, of which the genes are somewhat known for Winters, Durham, and Paris. These suppressors encode hairpin RNAs which match the sequence of driver genes (such as Dox), leading host RNA interference pathways to degrade Dox sequence. Autosomal suppressors of drive are known in Drosophila mediopunctata, Drosophila paramelanica, Drosophila quinaria, and Drosophila testacea, emphasizing the importance of these drive systems in natural populations.

Sterile insect technique

 

From Wikipedia, the free encyclopedia

The screw-worm fly was the first pest successfully eliminated from an area through the sterile insect technique, by the use of an integrated area-wide approach.

The sterile insect technique (SIT) is a method of biological insect control, whereby overwhelming numbers of sterile insects are released into the wild. The released insects are preferably male, as this is more cost-effective and the females may in some situations cause damage by laying eggs in the crop, or, in the case of mosquitoes, taking blood from humans. The sterile males compete with fertile males to mate with the females. Females that mate with a sterile male produce no offspring, thus reducing the next generation's population. Sterile insects are not self-replicating and, therefore, cannot become established in the environment. Repeated release of sterile males over low population densities can further reduce and in cases of isolation eliminate pest populations, although cost-effective control with dense target populations is subjected to population suppression prior to the release of the sterile males.

The technique has successfully been used to eradicate the screw-worm fly (Cochliomyia hominivorax) from North and Central America. Many successes have been achieved for control of fruit fly pests, most particularly the Mediterranean fruit fly (Ceratitis capitata) and the Mexican fruit fly (Anastrepha ludens). Active research is being conducted to determine this technique's effectiveness in combatting the Queensland fruit fly (Bactrocera tryoni).

Sterilization is induced through the effects of x-ray photon irradiation on the reproductive cells of the insects. SIT does not involve the release of insects modified through transgenic (genetic engineering) processes. Moreover, SIT does not introduce non-native species into an ecosystem.

History

The use of sterile males was first described by the Russian geneticist A.S. Serebrovsky in 1940, but the English-speaking world came up with the idea independently, and applied it practically around the 1950s. Raymond Bushland and Edward Knipling developed the SIT to eliminate screw-worms preying on warm-blooded animals, especially cattle; this was effective because female screw-worms mate only once. The larvae of these flies invade open wounds and eat into animal flesh, killing infected cattle within 10 days. In the 1950s, screw-worms caused annual losses to American meat and dairy supplies that were projected at above $200 million. Screw-worm maggots can also parasitize human flesh.

Entomologist Edward F. Knipling

Bushland and Knipling began searching for an alternative to chemical pesticides in the late 1930s when they were working at the United States Department of Agriculture Laboratory in Menard, Texas. At that time, the screw-worm was devastating livestock herds across the American South. Red meat and dairy supplies were affected across Mexico, Central America, and South America.

Knipling developed the theory of autocidal control – breaking the pest's reproductive cycle. Bushland's enthusiasm for Knipling's theory sparked the pair to search for a way to rear flies in a "factory" setting, and to find an effective way to sterilize flies.

Their work was interrupted by World War II, but they resumed their efforts in the early 1950s with successful tests on the screw-worm population of Sanibel Island, Florida. The sterile insect technique worked; near eradication was achieved using X-ray-sterilized flies.

Successes

The map shows the current (orange) and former (yellow) distribution area and the approximate seasonal spread of the screw-worm fly.

In 1954, the technique was used to eradicate screw-worms from the 176-square-mile (460 km2) island of Curaçao, off the coast of Venezuela. Screw-worms were eliminated in seven weeks, saving the domestic goat herds that were a source of meat and milk.

During the late 1950s to the 1970s, SIT was used to control the screw-worm population in the US. In the 1980s, Mexico and Belize eliminated their screw-worm problems with SIT. Eradication programs progressed across Central America in the 1990s, followed by the establishment of a biological barrier in Panama to prevent reinfestation from the south. The map shows the current and former distribution area and the approximate seasonal spread of the screw-worm fly.

In 1991, Knipling and Bushland's technique halted a serious outbreak of New World screw-worm in northern Africa. Programs against the Mediterranean fruit fly in Mexico, Florida and California use the SIT to maintain their fly-free status. The technique was used to eradicate the melon fly from Okinawa and in the fight against the tsetse fly in Africa.

The technique has suppressed insects threatening livestock, fruit, vegetable, and fiber crops. The technique was lauded for its environmental attributes: it leaves no residues and has no (direct) negative effect on nontarget species.

The technique has been a boon in protecting the agricultural products to feed the world's human population. Both Bushland and Knipling received worldwide recognition for their leadership and scientific achievements, including the 1992 World Food Prize. The technique were hailed by former U.S. Secretary of Agriculture Orville Freeman as "the greatest entomological achievement of the 20th century."

South Australia has since 2016 been producing tens of millions of sterile fruit flies a week during peak summer months, as part of a program to control and eventually eradicate the horticultural pests.

African trypanosomiasis

Sleeping sickness or African trypanosomiasis is a parasitic disease in humans. Caused by protozoa of genus Trypanosoma and transmitted by the tsetse fly, the disease is endemic in regions of sub-Saharan Africa, covering about 36 countries and 60 million people. An estimated 50,000 – 70,000 people are infected and about 40,000 die every year. The three most recent epidemics occurred in 1896 -1906, 1920, and 1970.

Studies of the tsetse fly show that females generally mate only once (occasionally twice). Studies found this process to be effective in preventing the scourge.

Successful programs

Targets

History of transboundary shipment of sterile insects

Transboundary shipment of sterile insects has taken place on a continuous basis for 60 years (since 1963). The total number of sterile insects shipped has been estimated at more than one trillion in thousands of shipments across borders to 23 recipient countries from 50 sterile insect factories in 25 countries. During this long period and many precedents, no problems associated with possible hazards have been identified, and thus the shipment of sterile insects have never been subjected to any regulatory action. The table shows the history of transboundary shipments which started in 1963 with the shipments of sterile Mexican fruit fly (Anastrepha ludens, Loew), from Monterrey, Mexico, to Texas, US.

Drawbacks

  • Naturally low population periods or repeated pesticide treatment are sometimes required to suppress populations before the use of sterile insects.
  • Sex separation can be difficult, though this can be easily performed on a large scale where genetic sexing systems have been developed as for the Mediterranean fruit fly.
  • Radiation, transport and release treatments can reduce male mating fitness.
  • The technique is species-specific. For instance, the technique must be implemented separately for each of the 6 economically important tsetse fly species.
  • Mass rearing and irradiation require precision processes. Failures have occurred when unexpectedly fertile breeding males were released.
  • Area-wide approach is more effective, as migration of wild insects from outside the control area could recreate the problem.
  • The cost of producing sufficient sterile insects can be prohibitive in some locations but decreases with economies of scale.

Conclusion and perspectives

Biotechnological approaches based on genetically modified organism (transgenic organisms) are still under development. However, since no legal framework exists to authorize the release of such organisms in nature, sterilization by irradiation remains the most used technique. A meeting was held at FAO headquarters in Rome, 8 to 12 April 2002 on "Status and Risk Assessment of the Use of Transgenic Arthropods in Plant Protection". The resulting proceedings of the meeting have been used by the North American Plant Protection Organization (NAPPO) to develop NAPPO Regional Standard No. 27 on "Guidelines for Importation and Confined Field release of Transgenic Arthropods", which might provide the basis for the rational development of the use of transgenic arthropods.

Economic benefits

Economic benefits have been demonstrated. The direct benefits of screwworm eradication to the North and Central American livestock industries are estimated to be over $1.5 billion/year, compared with an investment over half a century around $1 billion. Mexico protects a fruit and vegetable export market of over $3 billion/year through an annual investment around $25 million. Medfly-free status has been estimated to have opened markets for Chile's fruit exports up to $500 million. When implemented on an area-wide basis and a scaled rearing process, SIT is cost-competitive with conventional control, in addition to its environmental benefits.

A similar technique to SIT has recently been applied to weeds using irradiated pollen, resulting in deformed seeds that do not sprout.

Extraterrestrial liquid water

Extraterrestrial liquid water is water in its liquid state that naturally occurs outside Earth. It is a subject of wide interest because it is recognized as one of the key prerequisites for life as we know it and is thus surmised to be essential for extraterrestrial life.

Although many celestial bodies in the Solar System have a hydrosphere, Earth is the only celestial body known to have stable bodies of liquid water on its surface, with oceanic water covering 71% of its surface, which is essential to life on Earth. The presence of liquid water is maintained by Earth's atmospheric pressure and stable orbit in the Sun's circumstellar habitable zone, however, the origin of Earth's water remains uncertain.

The main methods currently used for confirmation are absorption spectroscopy and geochemistry. These techniques have proven effective for atmospheric water vapor and ice. However, using current methods of astronomical spectroscopy it is substantially more difficult to detect liquid water on terrestrial planets, especially in the case of subsurface water. Due to this, astronomers, astrobiologists and planetary scientists use habitable zone, gravitational and tidal theory, models of planetary differentiation and radiometry to determine the potential for liquid water. Water observed in volcanic activity can provide more compelling indirect evidence, as can fluvial features and the presence of antifreeze agents, such as salts or ammonia.

Using such methods, many scientists infer that liquid water once covered large areas of Mars and Venus. Water is thought to exist as liquid beneath the surface of some planetary bodies, similar to groundwater on Earth. Water vapour is sometimes considered conclusive evidence for the presence of liquid water, although atmospheric water vapour may be found to exist in many places where liquid water does not. Similar indirect evidence, however, supports the existence of liquids below the surface of several moons and dwarf planets elsewhere in the Solar System. Some are speculated to be large extraterrestrial "oceans". Liquid water is thought to be common in other planetary systems, despite the lack of conclusive evidence, and there is a growing list of extrasolar candidates for liquid water. In June 2020, NASA scientists reported that it is likely that exoplanets with oceans may be common in the Milky Way galaxy, based on mathematical modeling studies.

Significance

Water is a fundamental element for the biochemistry of all known living beings. Although some areas of Earth such as deserts are dryer than others, their local lifeforms are adapted to make efficient use of the scarce available water. No known lifeform can live completely without water. Although life eventually adapted to live on land, the first process of abiogenesis took place in an aquatic medium. As a result, the search for extraterrestrial water is closely related with the search of extraterrestrial life.

Water is one of the simplest molecules, composed of one oxygen and two hydrogen atoms, and can be found in all celestial bodies of the solar system. However, water is only useful for life in a liquid state, and extraterrestrial water is commonly found as water vapor or ice. Liquid water also has several properties that are beneficial for lifeforms. For example, unlike most other liquids, it becomes less dense when it solidifies rather than denser. As a result, if a body of water gets cold enough, the ice floats and eventually creates an ice layer, trapping liquid water and its ecosystems below. Without this property, lakes and oceans would become ice in their full size, along with any creatures living in them.

Liquid water in the Solar System

As of December 2015, the confirmed liquid water in the Solar System outside Earth is 25–50 times the volume of Earth's water (1.3 billion km3), i.e. about 3.25-6.5 × 1010 km3 (32.5 to 65 billion km3) and 3.25-6.5 × 1019 tons (32.5 to 65 billion tons) of water.

Mars

The Mars ocean theory suggests that nearly a third of the surface of Mars was once covered by water, though the water on Mars is no longer oceanic. Much of it now resides in the ice caps, in a solid state.

A cross-section of Mars underground ice is exposed at the steep slope that appears bright blue in this enhanced-color view from the MRO. The scene is about 500 meters wide. The scarp drops about 128 meters from the level ground in the upper third of the image.

Water on Mars exists today almost exclusively as ice, with a small amount present in the atmosphere as vapour. Some liquid water may occur transiently on the Martian surface today but only under certain conditions. No large standing bodies of liquid water exist because the atmospheric pressure at the surface averages just 600 pascals (0.087 psi)—about 0.6% of Earth's mean sea level pressure—and because the global average temperature is far too low (210 K (−63 °C)), leading to either rapid evaporation or freezing. Features called recurring slope lineae are thought to be caused by flows of brine — hydrated salts.

In July 2018, scientists from the Italian Space Agency reported the detection of a subglacial lake on Mars, 1.5 kilometres (0.93 mi) below the southern polar ice cap, and spanning 20 kilometres (12 mi) horizontally, the first evidence for a stable body of liquid water on the planet. Because the temperature at the base of the polar cap is estimated at 205 K (−68 °C; −91 °F), scientists assume that the water may remain liquid due to the antifreeze effect of magnesium and calcium perchlorates. The 1.5-kilometre (0.93 mi) ice layer covering the lake is composed of water ice with 10 to 20% admixed dust, and seasonally covered by a 1-metre (3 ft 3 in)-thick layer of CO2 ice.

Europa

Scientists' consensus is that a layer of liquid water exists beneath the surface of Europa, a moon of Jupiter and that heat from tidal flexing allows the subsurface ocean to remain liquid. It is estimated that the outer crust of solid ice is approximately 10–30 km (6–19 mi) thick, including a ductile "warm ice" layer, which could mean that the liquid ocean underneath may be about 100 km (60 mi) deep. This leads to a volume of Europa's oceans of 3 × 1018 m3 (3 billion km3), slightly more than twice the volume of Earth's oceans.

Enceladus

Enceladus, a moon of Saturn, has shown geysers of water, confirmed by the Cassini spacecraft in 2005 and analyzed more deeply in 2008. Gravimetric data in 2010–2011 confirmed a subsurface ocean. While previously believed to be localized, most likely in a portion of the southern hemisphere, evidence revealed in 2015 now suggests the subsurface ocean is global in nature.

In addition to water, these geysers from vents near the south pole contained small amounts of salt, nitrogen, carbon dioxide, and volatile hydrocarbons. The melting of the ocean water and the geysers appear to be driven by tidal flux from Saturn.

Ganymede

A subsurface saline ocean is theorized to exist on Ganymede, a moon of Jupiter, following observation by the Hubble Space Telescope in 2015. Patterns in auroral belts and rocking of the magnetic field suggest the presence of an ocean. It is estimated to be 100 km deep with the surface lying below a crust of 150 km of ice. As of 2015, the precise quantity of liquid water on Ganymede is highly uncertain (1–33 times as much as Earth).

Ceres

Ceres appears to be differentiated into a rocky core and icy mantle, and may have a remnant internal ocean of liquid water under the layer of ice. The surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clay. In January 2014, emissions of water vapor were detected from several regions of Ceres. This was unexpected, because large bodies in the asteroid belt do not typically emit vapor, a hallmark of comets. Ceres also features a mountain called Ahuna Mons that is thought to be a cryovolcanic dome that facilitates the movement of high viscosity cryovolcanic magma consisting of water ice softened by its content of salts.

Ice giants

The "ice giant" (sometimes known as "water giant") planets Uranus and Neptune are thought to have a supercritical water ocean beneath their clouds, which accounts for about two-thirds of their total mass, most likely surrounding small rocky cores, although a 2006 study by Wiktorowicz and Ingersall ruled out the possibility of such a water "ocean" existing on Neptune. This kind of planet is thought to be common in extrasolar planetary systems.

Pluto

In June 2020, astronomers reported evidence that the dwarf planet Pluto may have had a subsurface ocean, and consequently may have been habitable, when it was first formed.

Indicators, methods of detection and confirmation

Most known extrasolar planetary systems appear to have very different compositions to the Solar System, though there is probably sample bias arising from the detection methods.

Spectroscopy

Absorption spectrum of liquid water
Liquid water has not been detected in spectroscopic analysis of suspected seasonal Martian flows.

Liquid water has a distinct absorption spectroscopy signature compared to other states of water due to the state of its hydrogen bonds. Despite the confirmation of extraterrestrial water vapor and ice, however, the spectral signature of liquid water is yet to be confirmed outside of Earth. The signatures of surface water on terrestrial planets may be undetectable through thick atmospheres across the vast distances of space using current technology.

Seasonal flows on warm Martian slopes, though strongly suggestive of briny liquid water, have yet to indicate this in spectroscopic analysis.

Water vapor has been confirmed in numerous objects via spectroscopy, though it does not by itself confirm the presence of liquid water. However, when combined with other observations, the possibility might be inferred. For example, the density of GJ 1214 b would suggest that a large fraction of its mass is water and follow-up detection by the Hubble telescope of the presence of water vapor strongly suggests that exotic materials like 'hot ice' or 'superfluid water' may be present.

Magnetic fields

For the Jovian moons Ganymede and Europa, the existence of a sub-ice ocean is inferred from the measurements of the magnetic field of Jupiter. Since conductors moving through a magnetic field produce a counter-electromotive field, the presence of the water below the surface was deduced from the change in magnetic field as the moon passed from the northern to southern magnetic hemisphere of Jupiter.

Geological indicators

Thomas Gold has posited that many Solar System bodies could potentially hold groundwater below the surface.

It is thought that liquid water may exist in the Martian subsurface. Research suggests that in the past there was liquid water flowing on the surface, creating large areas similar to Earth's oceans. However, the question remains as to where the water has gone. There are a number of direct and indirect proofs of water's presence either on or under the surface, e.g. stream beds, polar caps, spectroscopic measurement, eroded craters or minerals directly connected to the existence of liquid water (such as Goethite). In an article in the Journal of Geophysical Research, scientists studied Lake Vostok in Antarctica and discovered that it may have implications for liquid water still being on Mars. Through their research, scientists came to the conclusion that if Lake Vostok existed before the perennial glaciation began, that it is likely that the lake did not freeze all the way to the bottom. Due to this hypothesis, scientists say that if water had existed before the polar ice caps on Mars, it is likely that there is still liquid water below the ice caps that may even contain evidence of life.

"Chaos terrain", a common feature on Europa's surface, is interpreted by researchers studying images of Europa taken by NASA's Galileo spacecraft as regions where the subsurface ocean has melted through the icy crust.

Volcanic observation

A possible mechanism for cryovolcanism on bodies like Enceladus

Geysers have been found on Enceladus, a moon of Saturn, and Europa, moon of Jupiter. These contain water vapour and could be indicators of liquid water deeper down. It could also be just ice. In June 2009, using data gathered by NASA's Casini spacecraft, researchers noticed that Enceladus wobbled in a certain way as it orbited Saturn. That wobble indicated that the moon's icy crust didn't extend all the way to its core — instead, it rested on a global ocean, the researchers concluded. was put forward for salty subterranean oceans on Enceladus. On 3 April 2014, NASA reported that evidence for a large underground ocean of liquid water on Enceladus had been found by the Cassini spacecraft. According to the scientists, evidence of an underground ocean suggests that Enceladus is one of the most likely places in the solar system to "host microbial life". Material from Enceladus' south polar jets contains salty water and organic molecules, the basic chemical ingredients for life," said Linda Spilker, Cassini's project scientist at JPL. "Their discovery expanded our view of the 'habitable zone' within our solar system and in planetary systems of other stars. Emissions of water vapor have been detected from several regions of the dwarf planet Ceres, combined with evidence of ongoing cryovalcanic activity.

Gravitational evidence

Saturn's tiny moon Mimas, the Solar System's smallest round body, may be a new class of "stealth ocean world".

Scientists' consensus is that a layer of liquid water exists beneath Europa's surface, and that heat energy from tidal flexing allows the subsurface ocean to remain liquid. The first hints of a subsurface ocean came from theoretical considerations of tidal heating (a consequence of Europa's slightly eccentric orbit and orbital resonance with the other Galilean moons).

Scientists used gravitational measurements from the Cassini spacecraft to confirm a water ocean under the crust of Enceladus. Such tidal models have been used as theories for water layers in other Solar System moons. According to at least one gravitational study on Cassini data, Dione has an ocean 100 kilometers below the surface.

Anomalies in the orbital libration of Saturn's moon Mimas combined with models of tidal mechanics led scientists in 2022 to propose that it harbours an internal ocean. The finding has surprised many who believed it was not possible for the Solar System's smallest round body, which was previously believed to be frozen solid, and has led to the classification of a new type of "stealth ocean world".

Ground penetrating radio

Site of south polar Martian subglacial water body (reported July 2018)

Scientists have detected liquid water using radio signals. The radio detection and ranging (RADAR) instrument of the Cassini probe was used to detect the existence of a layer of liquid water and ammonia beneath the surface of Saturn's moon Titan that are consistent with calculations of the moon's density. Ground penetrating radar and dielectric permittivity data from the MARSIS instrument on Mars Express indicates a 20-kilometer-wide stable body of briny liquid water in the Planum Australe region of planet Mars.

Density calculation

Artists conception of the subsurface water ocean confirmed on Enceladus

Planetary scientists can use calculations of density to determine the composition of planets and their potential to possess liquid water, though the method is not highly accurate as the combination of many compounds and states can produce similar densities.

Models of Saturn's moon Titan density indicate the presence of a subsurface ocean layer. Similar density estimations are strong indicators of an subsurface ocean on Enceladus.

Initial analysis of 55 Cancri e's low density indicated that it consisted 30% supercritical fluid which Diana Valencia of the Massachusetts Institute of Technology proposed could be in the form of salty supercritical water, though follow-up analysis of its transit failed to detect traces of either water or hydrogen.

GJ 1214 b was the second exoplanet (after CoRoT-7b) to have an established mass and radius less than those of the giant Solar System planets. It is three times the size of Earth and about 6.5 times as massive. Its low density indicated that it is likely a mix of rock and water, and follow-up observations using the Hubble telescope now seem to confirm that a large fraction of its mass is water, so it is a large waterworld. The high temperatures and pressures would form exotic materials like 'hot ice' or 'superfluid water'.

Models of radioactive decay

Models of heat retention and heating via radioactive decay in smaller icy Solar System bodies suggest that Rhea, Titania, Oberon, Triton, Pluto, Eris, Sedna, and Orcus may have oceans underneath solid icy crusts approximately 100 km thick. Of particular interest in these cases is the fact that the models indicate that the liquid layers are in direct contact with the rocky core, which allows efficient mixing of minerals and salts into the water. This is in contrast with the oceans that may be inside larger icy satellites like Ganymede, Callisto, or Titan, where layers of high-pressure phases of ice are thought to underlie the liquid water layer.

Models of radioactive decay suggest that MOA-2007-BLG-192Lb, a small planet orbiting a small star could be as warm as the Earth and completely covered by a very deep ocean.[64]

Internal differentiation models

Diagram showing a possible internal structure of Ceres

Models of Solar System objects indicate the presence of liquid water in their internal differentiation.

Some models of the dwarf planet Ceres, largest object in the asteroid belt indicate the possibility of a wet interior layer. Water vapor detected to be emitted by the dwarf planet may be an indicator, through sublimation of surface ice.

A global layer of liquid water thick enough to decouple the crust from the mantle is thought to be present on Titan, Europa and, with less certainty, Callisto, Ganymede and Triton. Other icy moons may also have internal oceans, or have once had internal oceans that have now frozen.

Habitable zone

Artist's impression of a class II planet with water vapor clouds, as seen from a hypothetical large moon with surface liquid water

A planet's orbit in the circumstellar habitable zone is a popular method used to predict its potential for surface water at its surface. Habitable zone theory has put forward several extrasolar candidates for liquid water, though they are highly speculative as a planet's orbit around a star alone does not guarantee that a planet it has liquid water. In addition to its orbit, a planetary mass object must have the potential for sufficient atmospheric pressure to support liquid water and a sufficient supply of hydrogen and oxygen at or near its surface.

The Gliese 581 planetary system contains multiple planets that may be candidates for surface water, including Gliese 581c, Gliese 581d, might be warm enough for oceans if a greenhouse effect was operating, and Gliese 581e.

Gliese 667 C has three of them are in the habitable zone including Gliese 667 Cc is estimated to have surface temperatures similar to Earth and a strong chance of liquid water.

Kepler-22b one of the first 54 candidates found by the Kepler telescope and reported is 2.4 times the size of the Earth, with an estimated temperature of 22 °C. It is described as having the potential for surface water, though its composition is currently unknown.

Among the 1,235 possible extrasolar planet candidates detected by NASA's planet-hunting Kepler space telescope during its first four months of operation, 54 are orbiting in the parent star's habitable 'Goldilocks' zone where liquid water could exist. Five of these are near Earth-size.

On 6 January 2015, NASA announced further observations conducted from May 2009 to April 2013 which included eight candidates between one and two times the size of Earth, orbiting in a habitable zone. Of these eight, six orbit stars that are similar to the Sun in size and temperature. Three of the newly confirmed exoplanets were found to orbit within habitable zones of stars similar to the Sun: two of the three, Kepler-438b and Kepler-442b, are near-Earth-size and likely rocky; the third, Kepler-440b, is a super-Earth.

Water rich circumstellar disks

Long before the discovery of water on asteroids, on comets, and on dwarf planets beyond Neptune, the Solar System's circumstellar disks, beyond the snow line, including the asteroid belt and the Kuiper belt were thought to contain large amounts of water and these were believed to be the Origin of water on Earth. Given that many types of stars are thought to blow volatiles from the system through the photoevaporation effect, water content in circumstellar disks and rocky material in other planetary systems are very good indicators of a planetary system's potential for liquid water and a potential for organic chemistry, especially if detected within the planet forming regions or the habitable zone. Techniques such as interferometry can be used for this.

In 2007, such a disk was found in the habitable zone of MWC 480. In 2008, such a disk was found around the star AA Tauri. In 2009, a similar disk was discovered around the young star HD 142527.

In 2013, a water-rich debris disk around GD 61 accompanied by a confirmed rocky object consisting of magnesium, silicon, iron, and oxygen. The same year, another water rich disk was spotted around HD 100546 has ices close to the star.

There is no guarantee that the other conditions will be found that allow liquid water to be present on a planetary surface. Should planetary mass objects be present, a single, gas giant, with or without planetary mass moons, orbiting close to the circumstellar habitable zone, could prevent the necessary conditions from occurring in the system. However, it would mean that planetary mass objects, such as the icy bodies of the solar system, could have abundant quantities of liquid within them.

History

Lunar maria are vast basaltic plains on the Moon that were thought to be bodies of water by early astronomers, who referred to them as "seas". Galileo expressed some doubt about the lunar 'seas' in his Dialogue Concerning the Two Chief World Systems.

Before space probes were landed, the idea of oceans on Venus was credible science, but the planet was discovered to be much too hot.

Telescopic observations from the time of Galileo onward have shown that Mars has no features resembling watery oceans. Mars' dryness was long recognized, and gave credibility to the spurious Martian canals.

Ancient water on Venus

NASA's Goddard Institute for Space Studies and others have postulated that Venus may have had a shallow ocean in the past for up to 2 billion years, with as much water as Earth. Depending on the parameters used in their theoretical model, the last liquid water could have evaporated as recently as 715 million years ago. Currently, the only known water on Venus is in the form of a tiny amount of atmospheric vapor (20 ppm). Hydrogen, a component of water, is still being lost to space as detected by ESA's Venus Express spacecraft.

Evidence of past surface water

An artist's impression of ancient Mars and its hypothesized oceans based on geological data

Assuming that the giant-impact hypothesis is correct, there were never real seas or oceans on the Moon, only perhaps a little moisture (liquid or ice) in some places, when the Moon had a thin atmosphere created by degassing of volcanoes or impacts of icy bodies.

The Dawn space probe found possible evidence of past water flow on the asteroid Vesta, leading to speculation of underground reservoirs of water-ice.

Astronomers speculate that Venus had liquid water and perhaps oceans in its very early history. Given that Venus has been completely resurfaced by its own active geology, the idea of a primeval ocean is hard to test. Rock samples may one day give the answer.

It was once thought that Mars might have dried up from something more Earth-like. The initial discovery of a cratered surface made this seem unlikely, but further evidence has changed this view. Liquid water may have existed on the surface of Mars in the distant past, and several basins on Mars have been proposed as dry sea beds. The largest is Vastitas Borealis; others include Hellas Planitia and Argyre Planitia.

There is currently much debate over whether Mars once had an ocean of water in its northern hemisphere, and over what happened to it if it did. Findings by the Mars Exploration Rover mission indicate it had some long-term standing water in at least one location, but its extent is not known. The Opportunity Mars rover photographed bright veins of a mineral leading to conclusive confirmation of deposition by liquid water.

On 9 December 2013, NASA reported that the planet Mars had a large freshwater lake (which could have been a hospitable environment for microbial life) based on evidence from the Curiosity rover studying Aeolis Palus near Mount Sharp in Gale Crater.

Liquid water on comets and asteroids

Comets contain large proportions of water ice, but are generally thought to be completely frozen due to their small size and large distance from the Sun. However, studies on dust collected from comet Wild-2 show evidence for liquid water inside the comet at some point in the past. It is yet unclear what source of heat may have caused melting of some of the comet's water ice.

Nevertheless, on 10 December 2014, scientists reported that the composition of water vapor from comet Churyumov–Gerasimenko, as determined by the Rosetta spacecraft, is substantially different from that found on Earth. That is, the ratio of deuterium to hydrogen in the water from the comet was determined to be three times that found for terrestrial water. This makes it very unlikely that water found on Earth came from comets such as comet Churyumov–Gerasimenko according to the scientists.

The asteroid 24 Themis was the first found to have water, including liquid pressurised by non-atmospheric means, dissolved into mineral through ionising radiation. Water has also been found to flow on the large asteroid 4 Vesta heated through periodic impacts.

Extrasolar habitable zone candidates for water

Exoplanets potentially containing water (artwork; 17 August 2018) (Left to right: Kepler-22b, Kepler-69c, Kepler-452b, Kepler-62f, Kepler-186f.)

Most known extrasolar planetary systems appear to have very different compositions compared to that of the Solar System, though there may be sample bias arising from the detection methods.

The goal of current searches is to find Earth-sized planets in the habitable zone of their planetary systems (also sometimes called the "Goldilocks zone"). Planets with oceans could include Earth-sized moons of giant planets, though it remains speculative whether such 'moons' really exist. There is speculation that rocky planets hosting water may be commonplace throughout the Milky Way.

In July 2022, water was detected on the exoplanet WASP-96b based on spectrum studies with the James Webb Space Telescope. In August 2022, water was detected on the exoplanet TOI-1452 b based on studies with data from the Transiting Exoplanet Survey Satellite (TESS).

Memory and trauma

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