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162173 Ryugu, provisional designation 1999 JU3, is a near-Earth object and a potentially hazardous asteroid of the Apollo group. It measures approximately 1 kilometer (0.6 mi) in diameter and is a dark object of the rare spectral type Cg, with qualities of both a C-type asteroid and a G-type asteroid.
Ryugu was discovered on 10 May 1999 by astronomers with the Lincoln Near-Earth Asteroid Research at the Lincoln Lab's ETS near Socorro, New Mexico, in the United States. It was given the provisional designation 1999 JU3.
The Japan Aerospace Exploration Agency (JAXA) spacecraft Hayabusa 2 was launched in December 2014 and successfully arrived at the asteroid on 27 June 2018. It is planned to return material from the asteroid to Earth by the end of 2020.
The Hayabusa2 mission includes four rovers with various scientific instruments. On 21 September 2018, the first two of these rovers, which will hop around the surface of the asteroid, were released from Hayabusa2.
On September 22, 2018, JAXA confirmed the two rovers had successfully touched down on Ryugu's surface. Three images were published; two during descent to the asteroid and one after MINERVA-II1A touched down. This marks the first time a mission has completed a successful landing on a fast-moving asteroid body.
TRKLST:
Totality during the lunar eclipse of 27 July 2018. Direct sunlight is being blocked by the Earth, and the only light reaching it is sunlight refracted by Earth's atmosphere, producing a reddish color.
A lunar eclipse occurs when the Moon passes directly behind Earth and into its shadow. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy), with Earth between the other two. A lunar eclipse can occur only on the night of a full moon. The type and length of a lunar eclipse depend on the Moon's proximity to either node of its orbit.
During a total lunar eclipse, Earth completely blocks direct sunlight from reaching the Moon. The only light reflected from the lunar surface has been refracted by Earth's atmosphere. This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light. Due to this reddish color, a totally eclipsed Moon is sometimes called a blood moon.
Unlike a solar eclipse, which can be viewed only from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. A total lunar eclipse lasts a few hours, whereas a total solar eclipse lasts only a few minutes as viewed from any given place, due to the smaller size of the Moon's shadow. Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are dimmer than the full Moon.
Do Androids Dream of Electric Sheep? (retitled Blade Runner: Do Androids Dream of Electric Sheep? in some later printings) is a science fiction novel by American writer Philip K. Dick, first published in 1968. The novel is set in a post-apocalyptic San Francisco, where Earth's life has been greatly damaged by nuclear global war. Most animal species are endangered or extinct from extreme radiation poisoning, so that owning an animal is now a sign of status and empathy, an attitude encouraged towards animals. The book served as the primary basis for the 1982 film Blade Runner, and many elements and themes from it were used in its 2017 sequel Blade Runner 2049.
The main plot follows Rick Deckard, a bounty hunter who is tasked with "retiring" (i.e. killing) six escaped Nexus-6 model androids, while a secondary plot follows John Isidore, a man of sub-par IQ who aids the fugitive androids. In connection with Deckard's mission, the novel explores the issue of what it is to be human. Unlike humans, the androids are said to possess no sense of empathy.
Do Androids Dream of Electric Sheep? (retitled Blade Runner: Do Androids Dream of Electric Sheep? in some later printings) is a science fiction novel by American writer Philip K. Dick, first published in 1968. The novel is set in a post-apocalyptic San Francisco, where Earth's life has been greatly damaged by nuclear global war. Most animal species are endangered or extinct from extreme radiation poisoning, so that owning an animal is now a sign of status and empathy, an attitude encouraged towards animals. The book served as the primary basis for the 1982 film Blade Runner, and many elements and themes from it were used in its 2017 sequel Blade Runner 2049.
The main plot follows Rick Deckard, a bounty hunter who is tasked with "retiring" (i.e. killing) six escaped Nexus-6 model androids, while a secondary plot follows John Isidore, a man of sub-par IQ who aids the fugitive androids. In connection with Deckard's mission, the novel explores the issue of what it is to be human. Unlike humans, the androids are said to possess no sense of empathy.
Whether there is life on Titan, the largest moon of Saturn, is at present an open question and a topic of scientific assessment and research. Titan is far colder than Earth, and its surface lacks stable liquid water, factors which have led some scientists to consider life there unlikely. On the other hand, its thick atmosphere is chemically active and rich in carbon compounds. On the surface there are bodies of liquid methane and ethane, and it is likely that there is a layer of liquid water under its ice shell; some scientists speculate that these liquid mixes may provide pre-biotic chemistry for living cells different from those on Earth.
In June 2010, scientists analysing data from the Cassini–Huygens mission reported anomalies in the atmosphere near the surface which could be consistent with the presence of methane-producing organisms, but may alternatively be due to non-living chemical or meteorological processes. The Cassini–Huygens mission was not equipped to look directly for micro-organisms or to provide a thorough inventory of complex organic compounds.
In general relativity, a white hole is a hypothetical region of spacetime which cannot be entered from the outside, although matter and light can escape from it. In this sense, it is the reverse of a black hole, which can only be entered from the outside and from which matter and light cannot escape. White holes appear in the theory of eternal black holes. In addition to a black hole region in the future, such a solution of the Einstein field equations has a white hole region in its past. However, this region does not exist for black holes that have formed through gravitational collapse, nor are there any known physical processes through which a white hole could be formed. Although information and evidence regarding white holes remains inconclusive, the 2006 GRB 060614 has been proposed as the first documented occurrence of a white hole.
Superflares are very strong explosions observed on stars with energies up to ten thousand times that of typical solar flares. The stars in this class satisfy conditions which should make them solar analogues, and would be expected to be stable over very long time scales. The original nine candidates were detected by a variety of methods. No systematic study was possible until the launch of the Kepler satellite, which monitored a very large number of solar-type stars with very high accuracy for an extended period. This showed that a small proportion of stars had violent outbursts, up to 10,000 times as powerful as the strongest flares known on the Sun. In many cases there were multiple events on the same star. Younger stars were more likely to flare than old ones, but strong events were seen on stars as old as the Sun.
Enceladus is the sixth-largest moon of Saturn. It is about 500 kilometers (310 mi) in diameter, about a tenth of that of Saturn’s largest moon, Titan. Enceladus is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the Solar System. Consequently, its surface temperature at noon only reaches −198 °C (−324 °F), far colder than a light-absorbing body would be. Despite its small size, Enceladus has a wide range of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrains that formed as recently as 100 million years ago.
Oumuamua is the first known interstellar object to pass through the Solar System. Formally designated 1I/2017 U1, it was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakala Observatory, Hawaii, on 19 October 2017, 40 days after it passed its closest point to the Sun. When first seen, it was about 33,000,000 km from Earth (about 85 times as far away as the Moon), and already heading away from the Sun.
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