Skip to main content
45 votes
Accepted

Apparent Ring of Craters on the Moon

Actually, most of the surface of the Moon is covered with craters like that. The exception are the large dark 'seas', which are in fact basaltic plains. The seas are mostly present on this side of the ...
Glorfindel's user avatar
  • 4,790
44 votes

Why is there a mountain inside the Herschel crater on Mimas?

In the extreme energy of a large impact, the rock behaves like a liquid (It isn't actually completely melted, though some is. The extreme forces cause the rock to flow). As the impactor hits the moon, ...
James K's user avatar
  • 125k
42 votes
Accepted

How do we distinguish old craters from new ones on the Moon?

Aside from the excellent points made in James K's answer, there are other ways to date craters. For example, when the rays of one crater overlay those of another, we know that the former is younger ...
Dan Hanson's user avatar
  • 1,161
25 votes

How do we distinguish old craters from new ones on the Moon?

The "weathering" processes are very slow compared to those on Earth. They are caused by the impact of micro-meteorites and the effect of the solar wind and cosmic radiation on the surface. The ...
James K's user avatar
  • 125k
21 votes

Can a crater form inside another crater

Yes, craters can overlap, and they do overlap. The exact theory of the origin of the Moon is still debated, but from the understanding of the Lunar geologic timescale we can see that it's been there, ...
planetmaker's user avatar
  • 19.9k
20 votes
Accepted

Can a crater form inside another crater

Yes, of course. Lunar surface is filled with overlapping craters. See Vendelinus for example. The relative ages of the craters can be determined by the amount of secondary craters per unit area which ...
Nilay Ghosh's user avatar
  • 4,698
15 votes
Accepted

How many iridium layers do we know, besides the K-Pg one (the dinosaur killer "smoking gun")?

There are other iridium anomalies, particularly the Devonian-Carboniferous boundary (D-C boundary), about 350 Ma ago. The K-Pg boundary is only 66 Ma old. Just because there is an iridium anomaly ...
Fred's user avatar
  • 2,169
15 votes
Accepted

How new is this crater?

To directly answer your questions before providing context: It takes "awhile" for brightness differences of ejecta to disappear on Mars, but unlike the Moon where it's around ~1 billion ...
Stuart Robbins's user avatar
14 votes
Accepted

What explains the distribution of new impact craters on Mars?

I was on the targeting team for one of the cameras that discovered most of these new impact craters. The reason for the distribution is simply because it's easiest to find "new" impact craters in the ...
tanyaofmars's user avatar
12 votes
Accepted

Strange square-like formation on Mars

I looked at the image and annotated it based on what it most likely is: In black is the formation itself. In blue is a depression underneath it. In grey is part of the boundary of what you believed ...
HDE 226868's user avatar
  • 36.6k
11 votes

Can a crater form inside another crater

I know the question is about impact craters, but as it's not precised in the title, and for the sake of completeness: volcanic craters do overlap too. A large eruption can create a large crater, then ...
Jean-Marie Prival's user avatar
10 votes
Accepted

How do we know that ice from the S1094b event was from Mars surface and not from the impactor?

From Richardson et. al, all the small, high-speed debris gets ejected from an impact first, and ends up furthest from the impact point. This would include any intermixing of the impactor with Martian ...
Connor Garcia's user avatar
  • 16.3k
8 votes
Accepted

Why are lunar craters preferentially north-south aligned?

Speaking as the author of Robbins (2019 [I always get the date messed up since 2018 was when it was available, but technically the volume it's in is a 2019 year), you are seeing artifacts of how the ...
Stuart Robbins's user avatar
7 votes
Accepted

Is the boulder on the peak of Tycho Crater the core of the impactor, or is it a random rock?

It is just a rock. A complex crater like Tycho is formed in several stages as the rock behaves like a fluid. The initial impact completely destroys the impactor and excavates a large cavity in the ...
James K's user avatar
  • 125k
7 votes
Accepted

What caused these strange craters on Hyperion?

According to Thomas et al. (2007), these craters are not unusually deep: It is unlikely that unusual crater depths significantly enhance the sponge-like appearance. Crater depth-to-diameter ratios ...
Jean-Marie Prival's user avatar
7 votes

how big would an asteroid have to be to leave a crater on Earth

Roughly 25 Meters I don't know what you would consider a 'crater', because a pebble landing in mud will create a 'crater'. And very small particles can rain down as dust and make it all the way to the ...
Dan Hanson's user avatar
  • 1,161
7 votes

Have micrometeoroids been observed impacting the moon's surface?

Yes, they have been observed many times. The NELIOTA project is dedicated to observing meteorite impacts on the Moon by means of Earth-based observations of the night side through a 1.2 m diameter ...
Albert's user avatar
  • 2,182
6 votes
Accepted

How did the Archimedes crater fill with lava?

Great question! The mare lava bubbled up through fractures in the floor of the crater, burying its ring system and central peak.
AstroShannon's user avatar
6 votes
Accepted

On a lunar map, why is it labelled East on Earth, West on Moon?

Imagine you're lying down outside, looking up at the sky, with your body aligned so your head is pointing North, and your Feet are pointing South. If you look to your Left, you'll be looking East, and ...
notovny's user avatar
  • 4,788
5 votes

Age of Jezero crater on Mars

Jezero crater is roughly 50 km across, and it is emplaced within the wall of Isidis crater ("basin"). Isidis itself has seen a lot of erosion, but it has been dated by lots of different ...
Stuart Robbins's user avatar
5 votes
Accepted

If an asteroid was to collide with Earth, how much warning would we have?

Asteroids come in all shapes and sizes, and generally the bigger they are the easier they are to detect. Small asteroids, from a the size of sand grains (properly called meteoroids) to a few meters ...
James K's user avatar
  • 125k
5 votes
Accepted

What are the craters on the moon with peaks in the middle of them?

Nice picture! Those peaks are actually a very common feature in craters formed by large impacts. Craters with these features are known as "complex craters". Basically what happens is that when the ...
Phiteros's user avatar
  • 3,166
5 votes

What explains the distribution of new impact craters on Mars?

The simplest explanation for the latitudinal distribution would be that most small solar system bodies that could impact one of the planets happen to orbit near the ecliptic plane and Mars' orbital ...
honeste_vivere's user avatar
4 votes
Accepted

Elongated Moon crater statistics?

Elliptical craters can be studied three ways: Laboratory simulations, computer simulations, and observations. Laboratory simulations have not really been done in detail for this problem in decades (I ...
Stuart Robbins's user avatar
4 votes

How does one go about submitting a name for a newly-discovered lunar crater?

You use this from https://planetarynames.wr.usgs.gov/FeatureNameRequest. You need to follow the rules as set out in https://planetarynames.wr.usgs.gov/Page/Rules as well as following the themes for ...
Rob's user avatar
  • 2,035
4 votes
Accepted

How big can a crater get?

Theoretically, if you're talking crater to planet size, I (think) a crater that covers half or a bit more than half of the planet is possible if you have a dense planet (Say, Mercury) and a lighter, ...
userLTK's user avatar
  • 24.1k
4 votes
Accepted

Age of Occator Crater

Five years have passed, and several papers have been published about this. The latest, Neesemann et al. (2019), compiles previous results and propose a new age estimate. Or rather estimates, because ...
Jean-Marie Prival's user avatar
4 votes

What are the craters on the moon with peaks in the middle of them?

That is the rebound effect. Just like a rock falling into a pond causes a big ripple and a big drop to jump out in the center, the same happens with a rock striking the Moon. Refer to this ...
User24373's user avatar
  • 903
4 votes
Accepted

Where do asteroids impact upon the Earth most often?

The occur all over the world. On this image each yellow circle is an recent impact of a small asteroid the size of the circle is related to the energy of the fireball (the sizes of the circles don't ...
James K's user avatar
  • 125k
4 votes

How did the mountain range form in Galle crater?

Rapidly! Galle is a large (230km) crater. In the processes that occur in the aftermath of a massive impact, deep rocks can be pushed up. Often this creates a central peak, but it can also form a ring ...
James K's user avatar
  • 125k

Only top scored, non community-wiki answers of a minimum length are eligible