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BY ANDREW FAZEKAS, FREELANCE OCTOBER 5, 2011
The clear and crisp nights of October are a great time to catch autumn stargazing showpieces. And headlining is the king of all planets, Jupiter.
For the past month it's been hard to miss Jupiter in the late night sky since it outshines all other stars. Over the course of October, things will get more interesting, as it continues to crank up its brightness as it reaches opposition on Oct. 29 - making for a spectacular sight both with the naked eye and telescopes.
Opposition is an extra special time for stargazers because that's when Jupiter shines throughout the course of the night from dusk till dawn and represents the time when Earth comes closest to the gas giant. And Jupiter, in turn, shines most brightly in our sky. If we could look down from above the plane of the solar system, we would see the sun, Earth and Jupiter in near perfect alignment during this time.
Making it extra special this year is that gas giant is the nearest to Earth until the year 2022.
A whole lot of tweeking going on:
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Astronomers say they may have figured out why the planet Uranus seems to be lying on its side with respect to the Sun. A series of bumps from other solar system objects early in its life could explain the odd alignment, they propose.
Most planets spin along roughly the same plane they inhabit with respect to the Sun. That is, if we could picture the Sun as a big spinning top on a table, most planets would be small tops around it on the same surface, spinning normally. But Uranus would have to be envisioned as a member of this group that is for some reason spinning on its side. To be more precise, its spin axis is tilted by 98 degrees compared to its orbit around the Sun. Jupiter’s axis, by contrast, is tilted by only 3 degrees; Earth’s by 23; Saturn’s and Neptune’s, 29.
The conventional explanation is that Uranus was at some point knocked on its side by an impact from an object a few times heavier than Earth, which weighs a fifteenth as much as Uranus...
There remained one problem: in the simulations, the moons ended up orbiting Uranus backward compared to how they are really moving. A tweak fixed this, Morbidelli’s group found...
The finding is at odds with current theories of how planets form, which may now need adjusting, Morbidelli said. “The standard planet formation theory assumes that Uranus, Neptune and the cores of Jupiter and Sat*urn formed by accreting only small objects in the protoplanetary disk,” he explained. “They should have suffered no giant collisions.” Morbidelli presented the research Oct. 6 at the American Astronomical Society’s Division for Planetary Sciences and the European Planetary Science Congress in Nantes, France.
