Outermost planet Neptune reaches opposition on 2 September 2016, this year marking the 170th anniversary of the gas giant’s discovery. But you don’t have to wait six week to observe the farthest known planet of the solar system, because the waning gibbous Moon drops close by in the small hours of Saturday, 23 July as seen from the British Isles.
An international team of astronomers have discovered a new dwarf planet orbiting beyond Neptune. The object is roughly 435 miles in size, moving in a 700-year orbit that takes it more than 120 times further from the Sun than Earth. Designated 2015 RR245, it was found using the Canada-France-Hawaii Telescope on Maunakea, Hawaii.
New images captured by the NASA/ESA Hubble Space Telescope (HST) confirm the presence of a dark vortex roughly 3,000 miles (4,800 kilometres) across in the atmosphere of Neptune. Though similar features were seen during the Voyager 2 flyby of Neptune in 1989 and by the HST in 1994, this vortex is the first one observed on Neptune in the 21st century.
In the race towards the discovery of Planet Nine, scientists from around the world strive to calculate its orbit using the tracks left by the small bodies that move well beyond Neptune. Now, astronomers from Spain and Cambridge University have confirmed that the orbits of the six extreme trans-Neptunian objects that served as a reference to announce the existence of Planet Nine are not as stable as originally thought.
A four-planet system orbiting the star Kepler-223 in the constellation Cygnus is actually a rarity: Its planets, all miniature Neptunes nestled close to the star, are orbiting in a unique resonance that has been locked in for billions of years. For every three orbits of the outermost planet, the second orbits four times, the third six times and the innermost eight times.
Earlier this year scientists presented evidence for Planet Nine, a Neptune-mass planet in an elliptical orbit 10 times farther from our Sun than Pluto. New research examining theories how this planet could end up in such a distant orbit finds that most scenarios have low probabilities. Therefore, the presence of Planet Nine remains a bit of a mystery.
Humanity has visited Uranus only once, and that was exactly 30 years ago. NASA’s Voyager 2 spacecraft got its closest look at the mysterious, distant, gaseous planet on 24 January 1986. The probe sent back stunning images of the coldest planet known in our solar system and its moons during the flyby, which allowed for about 5½ hours of close study.
Orbiting a mere 3,700 miles above the surface of Mars, Phobos is closer to its planet than any other moon in the solar system. Mars’ gravity is drawing in the 17 × 14 × 11 mile body by about 6.6 feet (2 metres) every hundred years. The long, shallow grooves lining the surface of Phobos are likely early signs of its structural failure as scientists expect it to be pulled apart.
The existence of a fifth giant gas planet at the time of the solar system’s formation — in addition to Jupiter, Saturn, Uranus and Neptune that we know of today — was first proposed in 2011. Now astrophysicists at the University of Toronto have found that a close encounter with Jupiter about four billion years ago may have resulted in the fifth giant planet’s ejection from the solar system altogether.
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