Skip to main content
32 votes
Accepted

Is it possible that the Rosetta orbiter moved the comet when it crashed?

Yes, it did. But not by much. The comet has a mass of about $10^{13}$ kg. Rosetta had a mass (after fuel had been used up) of about 1300kg. The "impact" was at 0.9 m/s. This means that ...
James K's user avatar
  • 123k
24 votes
Accepted

If Theia really crashed into Earth, did it impact Earth's axial tilt?

TL;DR: Yes Long answer: Theia is a hypothesized ancient planet in the early Solar System that, according to the giant-impact hypothesis, collided with the early Earth around 4.5 billion years ago, ...
Nilay Ghosh's user avatar
  • 4,458
17 votes

What if the Earth was hit by a small asteroid having close to the speed of light?

If the Earth was hit by an asteroid having diameter of about 5 km and moving with the speed close to the speed of light? What would happen? According to https://what-if.xkcd.com/20/ The momentum ...
RedGrittyBrick's user avatar
16 votes
Accepted

Could this estimate of the size and mass of the Chicxulub Impactor be accurate?

Well, that article was never accepted for publication in any peer-review journal apparently. That said, estimates may vary widely depending on assumptions about the composition and velocity of the ...
Swike's user avatar
  • 3,926
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
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
13 votes

How well would the Moon protect the Earth from an Asteroid?

It would be much better for Earth if the impactor hit the moon... In this Worldbuilding answer, I used a paper on ejecta kinematics to do calculations for ejecta velocity upon impact. Without going ...
kingledion's user avatar
13 votes

What if the Earth was hit by a small asteroid having close to the speed of light?

It might be hard to find sources where such collisions have been rigorously modeled, but certainly the amount of kinetic energy available is enough to do some damage. The amount of kinetic energy is ...
uhoh's user avatar
  • 30.6k
12 votes

What if the Earth was hit by a small asteroid having close to the speed of light?

The kinetic energy of a relativistic mass is given by $(\gamma -1)mc^2$, where $m$ is the mass of the object and $\gamma$ is the Lorentz factor $(1 - v^2/c^2)^{-1/2}$, where $v$ is the speed. ...
ProfRob's user avatar
  • 153k
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
9 votes
Accepted

What if a global killer hit Mars?

Imagine a similar asteroid as Chicxulub, the one that likely killed the dinosaurs here on earth. It is thought to have impacted at about 20 km/s. Initial atmospheric effects: When the asteroid entered ...
Connor Garcia's user avatar
  • 16.3k
9 votes
Accepted

What would happen if Venus was hit by a Chicxulub-like meteor?

Question: Would the dense atmosphere and high surface pressure and temperature lead to a different result compared to what happened here on Earth? Short Answer: No. There will not be any significant ...
Kavin Ishwaran's user avatar
8 votes
Accepted

How well would the Moon protect the Earth from an Asteroid?

The Moon orbits the Earth from $\approx$ 380000 km, but its radius is only $\approx$ 3500 km. The sky has 41253 sq degrees, and the Moon covers only $\approx$ 0.25 sq degree from it. Thus, the ...
peterh's user avatar
  • 3,161
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

Are we less safe now that Arecibo is no more?

The linked article is copied from a university press release. Arecibo's article is more matter-of-fact but naturally also emphasizes the value of their own work. NASA Goldstone can do planetary radar ...
Mike G's user avatar
  • 18.7k
6 votes
Accepted

2019OK energy at impact

You can use the Purdue 'Impact Earth!' website to estimate the effects of impacts of objects of various size, speed and composition. As detailed in the accompanying documentation, which was published ...
astrosnapper's user avatar
  • 8,357
6 votes
Accepted

What percentage of a lunar meteor strike is blown back into space?

There are some invariances that actually lend themselves well to estimating an answer to this question. From the Deep Impact mission white paper: A 1 mm projectile striking a target at 10 km/s will ...
Connor Garcia's user avatar
  • 16.3k
6 votes
Accepted

Is there any known asteroid or comet whose path goes through the Earth?

JPL and ESA provide tools to search for small bodies meeting user-defined criteria. I tried: H <= 24 MOID <= 1e-4 au with each and got these results in common: (89959) 2002 NT7, an H=16.5 (~1....
Mike G's user avatar
  • 18.7k
6 votes
Accepted

Why do Jupiter impact events look dark brown?

The initial impacts are brighter. The team that observed the shoemaker levy impacts described them as "fireballs" and the initial pictures showed spots glowing bright after impact, though I'...
userLTK's user avatar
  • 24.1k
6 votes
Accepted

If Planet Nine indeed exists, how large a impact event there should be to be seen from Earth?

We can compare the brightness of a comet hitting planet 9 with the 1994 impact of Shoemaker-Levy 9 / SL9 on Jupiter. It was seen by Hubble, and Galileo which was orbiting Jupiter at the time. View ...
bandybabboon's user avatar
  • 4,250
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
5 votes
Accepted

Did a piece of Halley's comet strike the Earth 1,500 years ago?

Little pieces of Halley's comet hit the Earth every spring. It's called the Eta Aquarid meteor shower, but I think you are thinking of something bigger. Dallas Abbot's paper notes that at the 533-540 ...
James K's user avatar
  • 123k
5 votes

What if a global killer hit Mars?

A partial answer to this part: Would any volcanoes erupt? At a local scale (i.e., close to the impact), such an asteroid could melt the rock, see impactite. But this is not volcanism stricto sensu, ...
Jean-Marie Prival's user avatar
5 votes
Accepted

What if you 'placed' the Chicxulub asteroid onto the Earth?

An asteroid resting on Earth would be a mountain. Or, for smaller asteroids, a pile of gravel. Mountains are limited in altitude by the strength of stone to resist compression: a too tall mountain ...
Anders Sandberg's user avatar
4 votes

Celestial impacts

Yes, there is an observed impact of a comet into a celestial body. A fairly recent one in 1994 is the comet which impacted into Jupiter, Shoemaker-Levy-9 Here's a video of this event happening.
VvV's user avatar
  • 41
4 votes

Small changes to Earth's orbit caused by a large impact on the Moon

... and still remain within the habitable zone? Everything perturbs all the time. Every change in the distribution of mass in the solar system (or in the universe) perturbs the orbit of the Earth... ...
James K's user avatar
  • 123k
4 votes

What would a 220km diameter asteroid impact do to Earth?

Using the impact effects calculator The energy before impact (making a some reasonable assumptions) is $3.35 × 10^{27}$ Joules = $7.99 × 10^{11}$ MegaTons TNT, most of which would be deposited in the ...
James K's user avatar
  • 123k
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
Accepted

With only seemingly two measurements 30 minutes apart, how were astronomers able to determine that asteroid 2022 EB5's trajectory intersected Earth?

The object was already so close to the Earth that in the 30 min time difference between the observations it moved already 1/4 of the way further to the earth (from about 21 Earth radii distance to 16 ...
Thomas's user avatar
  • 3,484
4 votes

Is it possible that the Rosetta orbiter moved the comet when it crashed?

It had already moved the comet to whatever extent it was able, when the probe had gone into orbit around the comet. The future trajectory would be determined by the centre of mass of the comet and ...
nigel222's user avatar
  • 171

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