That question stumped scientists for years. There is still no surefire consensus, but there are two prevailing theories. Both theories posit that Venus initially rotated clockwise, like the other planets.
The longer-standing theory suggests that Venus is still rotating in the same direction that it always has, but at some point flipped on its axis, so that same rotation is now counter-clockwise relative to the Sun.
In the early years of this millennium, though, a new theory surfaced. That theory suggests that Venus never flipped at all; rather, it initially rotated clockwise, then at some point came to a stop, and began turning in the opposite direction.
Regardless of whether the planet flipped or reversed, though, research indicates that Venus was naturally more stable in a retrograde rotation. That means no matter the method of reversal, it was only a matter of time before Venus started spinning counter-clockwise.
So, you wondered how long does Venus take to orbit the Sun? That may have seemed like a simple question, and in a sense, it is: Venus orbits the Sun once every Earth days. One major point of interest is the way Venus rotates while orbiting the Sun. Venus takes Earth days—more than one full Venus year—to complete one rotation around its axis. That is one of the slowest rotations of any planet in the Solar System.
Even stranger, Venus actually rotates counter-clockwise; alone with Uranus, it is one of only two planets to do so. Buy Now. Special Price. Sky-Watcher Skyhawk Telescope. The ideal telescope of choice for beginner to intermediate astronomers who are looking to expand their skygazing experiences Visit Us. Search Want to search our collection? Search here. We use cookies to ensure you have the best browsing experience and to help us improve our website.
Find out more Accept Cookies. Close cookie banner. How did the planets form? When we look at the night sky, we see what astronomers call nebula, such as the Orion Nebula. These are regions where stars are being formed. The nebula are formed when older massive stars exploded supernova , creating huge regions of dust and gas.
Something then happens. If you drop a rock in water, you send a wave through the water. If you have a nearby supernova, you send a shockwave through the nebula. At that point, gravity takes over and the cloud of dust and gas begins to collapse and stars are formed. Often, when stars form, they leave behind enough material in orbit around them to form planets.
The gas and dust form a disk around the star. The dust particles hit each other, stick, and make bigger particles, eventually making what are called protoplanetary bodies and eventually planets. The stuff that does not make it into planets and their moons is what we now see as asteroids and comets. Astronomers have seen this happening see the images below! Orion Nebula Eagle Nebula star formation Planet in dust disk around star. For elementary school, it is not necessary to get into the details.
The closer a planet is to the Sun, the less time it takes for it to go around the Sun. It takes less time because the length of the orbit is shorter a smaller orbit , but it also moves faster in its orbit. Thanks to gravity, it has to move faster in its orbit to stay in orbit! Below are the distances of the terrestrial planets from the Sun and the length of their years.
Obliquity is simply a term for the tilt of the rotation axis of a planet, moon, etc. So, it applies to all objects as they all spin on an axis. It is an angle measured in degrees relative to the plane of its orbit around the Sun for a planet or asteroid or a planet for a moon.
Some values: Mercury: 0. There is less volume in the inner solar system compared to the outer solar system, so there was less material present in the protoplanetary disk to form planets much larger than the terrestrial planets.
Some computer simulations show terrestrial planets a couple to a few times more massive than Earth, but not much beyond that if they formed in the inner part of the disk. Farther from the Sun, in the protoplanetary disk, the temperature was low enough that solid ices could form from the gas it was too hot in the inner part of the disk for ices. Thus, at the distance where Jupiter is and beyond there was both more solid rocky material and more solid icy material for planets to form out of.
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.
0コメント