# Tag Info

2

The nemesis theory proposes that a low mass star or brown dwarf in highly elliptical orbit is a companion to our sun as a solution to the cyclical mass extinction problem (http://www.theatlantic.com/science/archive/2015/11/the-next-mass-extinction/413884/) and (http://www.space.com/22538-nemesis-star.html). Scientists noticed that some mass extinctions ...

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The current explanation for this is something called the frost line (which changes over time). At greater distances from the Sun, a body will receive less and less radiation, and so it will be colder than if it were closer to the Sun. Eventually, conditions become cold enough for volatiles to condense into grains. These volatiles make it possible for ...

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Cassini is supposed to have used its VIMS spectrometer to observe a Venus transit from Saturn in December 2012. NASA said it was a first. They were more interested in an absorption spectrum than an image. Celestia can model such events. Here is a video of a simulated grazing Jupiter transit from Saturn. There are similar videos of Saturn transits from ...

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Just for fun I did a limited analysis of Jupiter size planets found using radial velocity or astrometry (mostly the former) techniques with the following criteria: 1) Data from the on-line sources http://exoplanet.eu/catalog/bd%2B15_2375_b/ and http://www.exoplanets.org/ giving planets discovered through Apr. 2016. 2) Msini: 0.5-10 M(J) 3) Distance to star ...

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As one gets farther from the sun, the gravity from the planets themselves becomes relatively stronger. So if a body were in an orbit between, for example, Jupiter and Saturn, those two planets would soon make the intermediate body's orbit change. This is conceptually related to the latest definition of "a planet"; A planet must clear its general vicinity of ...

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When the solar system formed, there was an accretion disc, spinning around the newborn Sun. The Sun was emitting radiations, which pushed the lighter materials of the accretion disk (gases) further away, and kept the heavier materials (rocks) much closer. This is why gas giants are almost always further away than rocky planets. Almost. In the case of ...

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I programmed one by myself some time ago. I used full SI units in combination with doubles (64-bit floating numbers). They work great for the scale of our solar system and are still extremly precise. var sun = new Star(); sun.Position = new Vector3D(0,0,0); sun.Velocity = new Vector3D(0,0,0); sun.Mass = 1.998855e30; ...

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Consider a nearly circular orbit. On average, $v = 2 \pi r / T$, and the gravitational force balances the centrifugal force: $${G M m \over r^2} = {m v^2 \over r} = {4 \pi^2 m r \over T^2}$$ Solve for $G$ and substitute values for Earth's orbit around the Sun: $$G = {4 \pi^2 r^3 \over M T^2 } = 4 \pi^2 {\mathrm{AU}^3 \over M_{\odot} \ \mathrm{y}^2}$$ ...

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The Wikipedia article on apparent retrograde motion seems to have a table containing exactly what you are looking for: The apparent motion is observed when the projection of a planet is compared to the star background. There are no real change in the planetary orbits, but when for example the Earth catches up with Mars, it seems to move retrograde ...

1

I would propose Enceladus. Enceladus has diameter smaller than even Mercury. From the nearside of a tidally-locked moon, the parent planet, Saturn, would appear nearly stationary. Being stationary Saturn might be viewed as the “center of the universe” instead. Being on a moon as oppose to the parent planet, with other moons orbiting along with your own, it ...

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The sun by far occupies the largest part of the solar system's mass. The mass of the sun happens to be approximately $(1.98855±0.00025)×10^{30}$ kg. Which is immensely huge. By comparison the inter-planetary medium though may occupy a large volume is nowhere dense enough to even compare to the mass of the sun which is approximately 99% of the solar system's ...

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