Why are there craters on the moon

The rock is usually at least three to five times smaller, depending on the amount of energy generated. In fact, you can detect recent craters now that scientists have such wonderful high-resolution pictures of the moon. You can detect craters formed in the last 10 or 20 years. One famous crater on the moon is called Tycho. Though they were made in , these Apollo 14 astronauts' tracks were easily viewed from a NASA spacecraft in orbit around the moon in tracks highlighted in yellow.

The Moon has almost no erosion because it has no atmosphere. That means it has no wind, it has no weather, and it certainly has no plants. Almost nothing can remove marks on its surface once they are made. The second thing is something called tectonics.

Because of tectonics, the surface of Earth is recycled many times throughout its long history. As a result, very few rocks on Earth are as old as the rocks on the Moon. An extensive blanket of ejecta covers the area around the rim. Complex craters are large craters with complicated features.

Larger craters can have terraces, central peaks, and multiple rings. Copernicus is a large crater 93 kilometers or 60 miles wide on the Moon. The inner walls of the crater have collapsed to form a series of step-like terraces, and a central peak is visible in the center of the image.

A complex crater in the northern region of Mars. This crater is about 20 kilometers 12 miles across and has a large central peak and terraces around its rim. The ejecta blanket has lobes, which may indicate wet material was ejected, suggesting that subsurface water or melted ice was mixed into the debris.

Impact basins are very large impact structures that are more than kilometers miles in diameter. The largest impact basin on the Moon is kilometers miles in diameter and more than 12 kilometers 7 miles deep. Large impact basins are also found on other planets, including Mars and Mercury. The large circular dark areas in the image are impact basins, created as huge impactors struck the Moon. Lava later flowed across the low floors of the basins, giving them a darker, smoother appearance than the surrounding, brighter highlands.

The dark basins can be seen by the naked eye. Scientists describe other types of craters as well:. How are large craters different than small ones? Small craters often are simple bowl-shaped depressions. The structure of large craters is more complex because they collapse, forming terraces, central peaks, central pits, or multiple rings. Very large impact craters greater than kilometers miles across are called impact basins. What influences the size and shape of a crater?

The size and shape of the crater and the amount of material excavated depends on factors such as the velocity and mass of the impacting body and the geology of the surface. The faster the incoming impactor, the larger the crater. Typically, materials from space hit Earth at about 20 kilometers slightly more than 12 miles per second. Such a high-speed impact produces a crater that is approximately 20 times larger in diameter than the impacting object.

Scientists called these "mare" Latin for seas. That early volcanism deposited the basaltic rocks. Throughout its existence, the Moon has been bombarded by comets and asteroid chunks, and those created the many impact craters we see today. They are in pretty much the same shape they were after they were created. This is because there is no air or water on the Moon to erode or blow away the crater edges.

Since the Moon has been pounded by impactors and continues to be bombarded by smaller rocks as well as the solar wind and cosmic rays , the surface is also covered by a layer of broken rocks called regolith and a very fine layer of dust.

Beneath the surface lies a thick layer of fractured bedrock, which pays testament to the action of impacts over billions of years. It's about 1, miles across 2, kilometers. It's also among the oldest of the Moon's impact basins and formed just a few hundred million years or so after the Moon itself was formed. Scientists suspect that it was created when a slow-moving projectile also called an impactor crashed into the surface.

This object was probably several hundred feet across and came in from space at a low angle. Most craters have a pretty characteristic round shape, sometimes surrounded by circular ridges or wrinkles. A few have central peaks, and some have debris scattered around them. The shapes can tell scientists about the size and mass of the impactors and the angle of travel they followed as they smashed into the surface.

The general story of an impact follows a pretty predictable process. First, the impactor rushes toward the surface. On a world with an atmosphere, the object is heated by friction with the blanket of air. It starts to glow, and if it's heated enough, it may break apart and send showers of debris to the surface. When impactors strike the surface of a world, that sends a shockwave out from the impact site.