PV Gap

Virginia Said:

Suppose the masses of all bodies of the solar system doubled, but their orbits remained the same.?

We Answered:

If the sun doesn't double in mass the orbits remain the same. All the orbits can be pretty well approximated by the 1 body problem and have been stable for billions of years. If the sun doubles in mass, the force would double and the velocity would increase by a factor of sqrt(2) and the period would decrease by a factor of sqrt(2). This system can still be approximated by the 1 body problem and would, in general, be stable.

edit: damn...ninja'd

Carlos Said:

What are the Celestial Coordinates of the north poles of (all) bodies in the Solar System? How about Beyond?

We Answered:

This directory should give you the north polar CC for all the planets out to Pluto; the southern ones should be easy to extrapolate from these figures.

http://nssdc.gsfc.nasa.gov/planetary/pla…

Bruce Said:

Do all objects in space (solar system) reflect sunlight?

We Answered:

Some of the answers you already got are pretty good, but an easier explanation has to do with the color of objects, and not necessaritly the distance or whether they are black holes. Another detail you need to remember is that sunlight is only emitted by our star, the Sun, and it's too faint even for objects inside the Solar System.

If an object is black, light will not be reflected, and it cannot be seen by optical methods. There is a value called 'albedo' which is a measure of the reflectivity of light of an object. For example, the Moon has an albedo of around 7, which corresponds to 7%. If an object, like an asteroid, has an albedo of 0, it can only be measured by electromagnetic means.

Some asteroids are black, so it's not possible to know about their rotation periods. As far as stuff like Dark Matter, it's not about the color, it's that its gravitational effects can be measured.

Strictly speaking, it is possible that a planet could be black and invisible to us with our current technology, but it's not very likely. Right now there is an ongoing dispute about Sedna, an planet-like object in the Kuiper Belt that has its own satellite, but it's still not clear if it is a planet or a dwarf (planetoid.)

Glen Said:

What might the common direction of all the planet spin motions tell us about how the whole solar system formed?

We Answered:

As angular momentum is conserved it suggest that the molecular cloud from which the solar system formed was spinning itself. Much slower of course, as that cloud was much bigger than the solar system.

Edgar Said:

All the planets in the solar system orbiting the sun. Is our solar system itself orbiting something?

We Answered:

Kind of... all the stars in the Milky Way are rotating around a giant black hole in the center of the galaxy.

But we're all going around at such a SLOW rate you really couldn't call it orbiting (most stars will die out before they make it around 1 time -that's like 10 billion years).

Some scientists even think that our sun is actually going to leave the Milky Way in the future, that we're slowing moving out.

By the way, there is no "center of the universe" as some people put it. When physicists talk about the universe expanding, they're saying the actual fabric of space is expanding from since the big bang. So if anyone asks you where the big bang occurred... it occurred EVERYWHERE.... Wrap your head aroudn that!!

A little off-point but other people brought it up.

Elsie Said:

what is non-sense about the solar system going through the middle of the galaxy and killing us all in 2012?

We Answered:

The middle of the galaxy is 26,000 light years away - how could our solar system get that far in 3 years?
Its very easy to decide what is a hoax when you know a few basics of science (the people that spread these hoaxes count on others not knowing anything).