# Tag Info

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### Why are asteroids so much richer in precious metals than Earth's crust?

This is in part marketing hype by wanna-be asteroid mining companies. That said, some asteroids are suspected to be richer in precious metals than is the Earth's crust. For example, the Earth's crust ...
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### 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 ...
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### 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 ...
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### What will happen to a metal asteroid if it impacts the Earth? Will it disintegrate or will it stay intact?

Whether an asteroid survives the fall through the atmosphere depends on its size and structural integrity. Our understanding of large impacts is limited (we haven't observed any, and this is a very ...
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### Can earth grazers skip on the atmosphere more than once?

I believe the answer is yes, when the asteroid after the initial pass through the earth's atmosphere no longer has escape velocity relative to the earth, but enters an elliptical orbit around the ...
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### Asteroids in polar orbits?

To have an orbit perpendicular to the ecliptic plane, it would need to have an inclination of exactly 90 degrees. Orbits with inclination less than 90 degrees are prograde, and with greater are ...
• 14.1k

### 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 ...
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### Can earth grazers skip on the atmosphere more than once?

If by "more than once" you mean "more than once in a single visit", then that would seem impossible. After the first skip, the object is moving away from the earth. Either it has ...
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### 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. ...
• 118k
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### How is asteroidal rock formed?

Another major theory regarding the early solar system is that there was a relative abundance of short-lived radioactive isotopes at the time the solar system formed. These short-lived isotopes would ...
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### How is asteroidal rock formed?

One major theory for the evolution of the asteroid belt is that planetesimals (early precursors to planets) formed early in the development of the Solar System in Solar orbits around the asteroid belt....
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### What will happen to a metal asteroid if it impacts the Earth? Will it disintegrate or will it stay intact?

No, it will not. The kinetic energy released upon impact is more than sufficient to vaporise even a metal asteroid. Barringer crater was caused by a metallic object, and there's nothing left of it. ...
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### Will 3,600ft asteroid be visible at my location tonight?

When NASA says 5:50PM today, what location and/or timezone are they referring to? This particular website (eyes.nasa.gov) is using your system's local time to tell you the closest approach in your ...
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### Can earth grazers skip on the atmosphere more than once?

I will not commit to a "yes" or "no" answer, but instead refer to examples of artificial objects that do go at least down-up-down. From Space Exploration SE: Did the Apollo ...
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### following several unknown phenomena detected at the edge of the solar system, is there a 5th force which acts at the edge of the solar system?

I've reviewed your sources, but I don't think they make the claims you say they do. The first relates to interactions between solar wind electrons and cosmic rays. This interaction is complex and ...
• 91.4k
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### 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 ...
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### Will 3,600ft asteroid be visible at my location tonight?

The JPL Small Body Database shows this asteroid having a close approach to Earth at Jan 18 21:51 TDB or 21:50 UTC. NASA Eyes shows me that time in my local time zone. JPL HORIZONS estimates it peaking ...
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### How was a rock on the surface of asteroid 101955 Bennu first observed from Earth (Benben Saxum)?

I think it is the "boulder" discovered by Nolan et al. (2013). They used radar images from two ground-based observatories, from two different passes, to perform shape modeling: The radar ...
• 1,342
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### Are there any Hubble images of Polymele available?

HST Proposal 15144, entitled "Deep Search for Satellites Around the Lucy Mission Targets", has a data page with 24 Hubble images of Polymele (you need to go to page 2 of 2 of the table). An ...
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### Why are what end up being meteorites not in stable orbit as planets and large asteroids are?

A couple of factors. Firstly most small asteroids are in stable orbits. They don't approach any planets closely, and orbit in ellipses that are stable on timespans exceeding the age of the solar ...
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### Why are asteroids so much richer in precious metals than Earth's crust?

I have no knowledge of the quantified specifics, but would like to point out two effects that may be relevant: We already exploited the easiest precious metal deposits on the top of Earth's crust to ...

### Nature of faculae on Ceres? Do they glow in the dark?

No, they don't glow. The cameras on Dawn have been set to photograph the dark grey (nearly black) surface of Ceres, and the white faculae are therefore rather overexposed. Even whe catching the ...
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### Why haven't we had an "asteroid attack" until now?

That asteroid diagram is a bit misleading. It's showing the distribution of the asteroids, but it greatly exaggerates the sizes of all the bodies relative to the sizes of the orbits. Even the dot ...
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### What is the nature of the "blind spot issue" in asteroid detection systems?

I will have to look for a source for this, but basically the best way to search for small NEOs is to use image at thermal infrared wavelengths. At circa 1 AU the Sun illuminates them with about 1600 ...
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### How could a captured asteroid enter a circularized orbit?

It seems like there are two questions here: 1: How could a moonless planet capture a single asteroid into a closed orbit around the planet? In a 2-body orbital system, a moonless planet couldn't ...
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### Half life of retrograde asteroids?

In my opinion, most asteroids in retrograde orbits should continue to orbit in retrograde orbits for billions of years. Experts in orbital mechanics would have more expert opinions, of course. ...
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### What image analysis approaches/algorithms are used to detect near-Earth objects?

Near-Earth Objects (NEO’s) are detected from imagery frames. The methodology is to ‘look’ for a tiny bright spot from several images, that has its pattern of brightness, shape and movement. Currently ...
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### calculating MPC orbital uncertainty parameter U

Here is a screenshot of JPL SBDB's elements for asteroid 2021 GT2. The perihelion time tp is shown as a Julian date on the TDB timescale with uncertainty in days. If I evaluate the MPC formulas: <...
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### Are asteroids 2012 PM35 and 2020 OG106 aliases?

Look at this discussion on the minor planet mailing list from Feb 2022: Call me crazy, but it seems 2012 PM35 and 2020 OG106 actually are the same object, and all of the observations are correct. In ...
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