Why do closer planets orbit faster

This may have allowed the planets to grow much larger and eventually reach a mass that was so large that their gravity could begin capturing hydrogen and helium gas from the disk. This may be how the giant planets formed, although there is still a fair amount of debate.

Each planet, thanks to size, is different. On Earth, magma is brought to the surface by volcanic activity heat generated in the interior being brought to the surface , these rocks cool to form igneous rocks.

These rocks can react with the atmosphere weathering and erosion and form sedimentary rocks. All of these rocks can get reburied and create metamorphic rocks. Much of the volcanic activity and processes that lead to reburying rocks are the result of plate tectonics. We only see this on Earth. On Venus, which is about the same size as the Earth, we do not see evidence for plate tectonics, but we do see evidence for volcanism.

The atmosphere likely reacts with the rocks, but there probably isnt any mechanism to create metamorphic rocks and there is no water to create that kind of erosion or sedimentation though other things could rain out, like sulfuric acid.

Mars does not have plate tectonics, but does have past volcanism. It has a thin atmosphere, so there can be erosion and transport by wind great dust storms. There is evidence that the atmosphere used to be thicker, thick enough to have liquid water on the surface that would then lead to erosion and sedimentation, but not metamorphism. We are still learning about Mercury. It is a relatively dead object but does show evidence of past volcanism.

Because it is much smaller than the Earth or Venus, it cooled off and formed a fairly thick crust long ago. While Venus is about the same size as Earth, Mars is closer to Earth if the focus is on where life might exist elsewhere and where we might establish human colonies. The thin atmosphere does not make for ideal living conditions, but it is tolerable.

There is also evidence of water at the poles and ice trapped below the surface over much of the planet. Not really. Mercury, Venus, and Earth have iron cores. Mars probably has a smaller core because it is thought to contain less iron and may not have completely differentiated.

However, once you get to Jupiter and Saturn, their cores are dense just by the sheer pressure due to their size. It is thought that, in their interiors, Jupiter and Saturn have cores that are larger than the Earth maybe 10 times the size of the Earth for Jupiter.

It is thought that the pressure in the interior of Jupiter is about 40 million atmospheres. So whatever goes down there is going to be crushed to a fairly good density.

Based on our understanding of planet formation, you can estimate of how much of each element you would expect. For the Earth, there is not much iron on its surface. However, if you look at its density, its interior "profile" from studying earthquakes, and the fact that it has a magnetic field, you can determine that the iron is in the core-- it sank to the core when the Earth was molten. While our knowledge of the other terrestrial planets is not as good, one would expect that their early histories were similar to Earth's.

Again, by looking at things such as surface composition, density, etc, one can come up with interior profiles that require iron cores. There are two ways to estimate the surface temperatures of the planets.

You can make an initial guess based on how far they are from the Sun and by how much sunlight they appear to be absorbing closer to the Sun, hotter. You can also measure their temperature with infrared cameras. By seeing how much heat they give off, you can determine their temperature.

Venus and Mars have both similarities to the Earth. Venus is about the same size and it might be closer in geologic activity than Mars. Mars is colder than Earth, but closer to Earth in temperature. Skip to navigation Skip to main content. Johannes Kepler The Marvelous Lantern Johannes Kepler found a marvelous way out of his dilemma, how to ascertain the real shape of Earth's orbit.

Imagine a brightly shining lantern somewhere in the plane of the orbit. Assume we know that this lantern remains permanently in its place and thus forms a kind of fixed triangulation point for determining the Earth's orbit, a point which the inhabitants of Earth can take a sight on at any time of year.

As a result of this movement, the cloud will most likely have some slight rotation as seen from a point near its center. This rotation can be described as angular momentum, a conserved measure of its motion that cannot change. Conservation of angular momentum explains why an ice skater spins more rapidly as she pulls her arms in. As her arms come closer to her axis of rotation, her speed increases and her angular momentum remains the same.

Similarly, her rotation slows when she extends her arms at the conclusion of the spin. As an interstellar cloud collapses, it fragments into smaller pieces, each collapsing independently and each carrying part of the original angular momentum.

The rotating clouds flatten into protostellar disks, out of which individual stars and their planets form. By a mechanism not fully understood, but believed to be associated with the strong magnetic fields associated with a young star, most of the angular momentum is transferred into the remnant accretion disk.

Planets form from material in this disk, through accretion of smaller particles. In our solar system, the giant gas planets Jupiter, Saturn, Uranus, and Neptune spin more rapidly on their axes than the inner planets do and possess most of the system's angular momentum.

The sun itself rotates slowly, only once a month.