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.
Using a new process in planetary formation modelling, where planets grow from tiny bodies called “pebbles,” Southwest Research Institute scientists can explain why Mars is so much smaller than Earth. This same process also explains the rapid formation of the gas giants Jupiter and Saturn, as reported earlier this year.
Uranus, the seventh planet from the Sun, reaches opposition on 12 October. It is therefore best placed for observation during 2015 and reaches a respectable altitude as seen from the British Isles. It can be seen with the naked eye from dark sky sites, so here is our guide to tracking down this gas giant during October using nothing more than an average binocular.
When Pluto was reclassified as a dwarf planet in 2006, Neptune regained the title of the solar system’s outermost planet. Since this fascinating gas giant reached opposition on 1 September in the constellation Aquarius, now is a great time to seek it out. We show you how to locate Neptune with binoculars and small telescopes.