Although these two types of asteroid form the majority of examples, there are some that appear to be composed of little but metal and, again, there are metal meteorites found on Earth. Aside from composition, there are other important differences in the internal structure of the asteroids. Most are solid, indicating that they must have been molten at some point in their existence.
Others are 'rubble piles'. This means that they are loose collections of 'pieces', held together by the force of their gravity. These asteroids were formed in collisions. It's rubble left over from planet building, probably because there wasn't sufficient gravity there to pull a planet together and hold it together, up against the gravitational tugs of all of the other planets forming in the solar system. So that's really the reason.
Skip to main content. Earth Science. Articles Answers to Science Questions Why are planets spherical but meteorites irregularly shaped? Why are planets spherical but meteorites irregularly shaped? Part of the show Where does Phlegm come from? Play Download. Chris, I hope this is not a stupid question, but something has puzzled me a little bit in the observation of our planet earth, the planets, the moon, the sun, the stars.
J Regards Karin. Answer If you look at things from a long way away like the Sun, like the Earth, like Mars - yes, they do look like big circles in the sky, that's true. Previous Why would an open carport stop frost? Next How do I get into Pathology? Related Content Earth Science History. Volcanoes didn't do-in the dinosaurs. The faster an object in space spins, the more dramatic this effect is. As a result, it is much less spherical than Earth.
That is a difference of almost 12,km! Some stars are even more extreme. The bright star Altair, visible in the northern sky from Australia in the winter months, is one such oddity.
It spins once every nine hours or so. The closer you look into a question like this, the more you learn. But to answer it simply, the reason big astronomical objects are spherical or nearly spherical is that they are massive enough that their gravitational pull can overcome the strength of the material they are made from.
This article first appeared on The Conversation. These are much larger than comets. An asteroid only 5 km across would be classi- fied as small; Ceres, the largest, is times bigger than this. They show no coma activity and the reflectance spectrum is similar to that of asteroids. They are bigger than standard comets but smaller than a typical asteroid. The biggest reason as to why we study asteroids is because they can tell us about the origins of the Solar System, as they are considered to be the building blocks of the planets.
In planetary formation, lumps of rock, such as asteroids, coalesce to create minor planets and eventually planets. Yes, asteroids can have moons! Some of the larger asteroids in our Solar System actually do have moons. In , an tiny moon called Dactyl was discovered orbiting the large asteroid Ida. Dactyl is only about 1 mile wide, while Ida is about 19 miles across. It was first reported in and has been studied several times.
0コメント