Questions tagged [comets]

Icy bodies that usually consist of methane, water, and other materials that originate from beyond the jovian planets, and occasionally fall into the inner solar system giving off a massive tail as material is boiled off.

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Comet Bernardinelli-Bernstein; could it be a "planet-killer" and what could prevent it from getting close to us?

The huge "mega" comet C/2014 UN271 (Bernardinelli–Bernstein) 80 miles wide is coming towards Earth from the edge of our Solar System. It is supposed to only get to the middle of our Solar ...
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How is a comet visible when far from the Sun

The latest news tells of a super large "mega" comet C/2014 UN271 (Bernardinelli–Bernstein) approaching the Solar System in about 9 years. It must be very far from the Sun, so how do we ...
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How to model the kinematics of gases expelled from comets and planetary atmospheres?

Once the ices of comets sublimate, where do they move to, and with which equations do you describe their motion in the interplanetary medium? Similarly, where do the gases that are stripped from the ...
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What exactly did ALMA observe at 20 AU from the "Mega Comet Arriving From the Oort Cloud" that will pass in 2031?

Gizmodo's Mega Comet Arriving From the Oort Cloud Is 85 Miles Wide says: For the new study, Lellouch and his colleagues used the Atacama Large Millimeter Array (ALMA) in Chile to refine the comet’s ...
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What is going on with comet C/2021 A1 Leonard? Is it going to be bright this weekend or not?

I have to plan an excursion to try to find clear evening skies to try to see if we can spot comet C/2021 A1 Leonard about 10 to 15° above the ocean in the Southwest after sunset this weekend. I'm ...
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How close to escape velocity are most Oort-cloud comets?

User @antlersoft wrote a nice answer to my question on the difference between barycentric and heliocentric models of the solar system when applied to comets (edge cases of the systems). In a comment, @...
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7 votes
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What is the difference between barycentric-centered and heliocentric-centered coordinates?

When talking about celestial bodies orbiting the sun with a decently circular orbit or small aphelion, the heliocentric orbital parameters are almost identical to the barycentric parameters. However, ...
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What observational data was there that comet Leonard C/2021 A1 might have been dimming and/or breaking up?

Space.com's Comet Leonard, the brightest of the year, is fading and acting strange seems to be full of inexact language, like "something's wrong" and "unhealthy" and "goner&...
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Make a guide map to comet comet Leonard C/2021 A1 using Skyfield

Sky and Telescope's How Bright will Comet Leonard Get? includes the skymap and projected (possible) light curve for comet Leonard C/2021 A1 that will potentially reach +4 magnitude this month. It has ...
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Specific impulse of cometary outgassing?

Note: This question is related to Average DeltaV applied to a comet during outgassing? Rocket engines have a parameter called "specific impulse," which is the measurement (in seconds) of how ...
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Average DeltaV applied to a comet during outgassing?

Comets' orbits often change during perihelion passage due to the outgassing of volatiles. So I am wondering, how much change in velocity is applied each perihelion pass? What does this depend on?
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Role of aerobraking in cometary orbits?

I'm doing some research about comet perturbations, and have noticed that the outbound aphelion is often different from the inbound aphelion, particularly due to the gravitational influence of the ...
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The Kuiper Belt and Oort cloud [closed]

How come the comets and asteroids in the Kuiper belt and Oort cloud are kept in a gravitational field and they don't get pushed and pulled by the planets around them? I get why comets in the Oort ...
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3 votes
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Why haven't we had an "asteroid attack" until now?

We know that there is a big and dense ring of asteroids between the orbits of Jupiter and Mars and also "Trojans" and "Greeks" in Jupiter's orbit too. We also know that there are ...
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Is there any chance Comet Bernardinelli-Bernstein could collide with Earth?

At a size of 100 kilometers, this comet is ten times the one that exterminated the dinosaurs on Earth. It is headed towards our Solar System and expected to arrive in 2031. It is projected to swing by ...
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Disk-resolved vs disk-averaged photometry?

I have already read this question about the difference between disk-integrated and disk-resolved photometry. But what exactly is the difference between disk-resolved and disk-averaged photometry? I am ...
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Astronomic objects (and their distribution functions) appearing in an old computer game?

Many decades ago, when I learned coding, I was also reading a (red) book on the programming the 8080 processor which was full of code listings and their description. I was in particular fascinated by ...
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Mass loss rate in a typical visible-from-Earth comet

What is the typical range of a comet's mass loss per second to its dust and gas tails, while it is naked-eye visible from Earth? I'm aware this is going to be a very broad range and expect it to cover ...
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How does a comet crumble? Are there models for that?

Edit: Initially, the title was How does the crumbling sound? I am curious how comets degradate or even disintegrate over time, in particular while they are close enough to the Sun to have tails. Is ...
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Whether the comet is moving in an elliptical or hyperbolic orbit around the sun?

The time of observation after the first observation (in years), the distance between the earth and the comet (in AU) and the angle between the sun and the comet (in radians) is given. How to find ...
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Details about the next big comet 2014 UN271?

The announcent of the massive trans-Neptunian object 2014 UN271 to be a comet is rather new (June 22nd, 2021) and really exciting. That comet is rather huge (~100km diameter) and "falling toward ...
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Dotted line of moving objects observed on May 5th and May 12th [duplicate]

I saw a dotted line shooting star-like object May 5th and May 12th. It was longer than any meteor/shooting star tail or trail I've ever seen before. I mean longer in every way, the distance it ...
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2 votes
1 answer
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Is scattering efficiency of dust related to albedo?

I know that the scattering cross-sections of dust in comets depend on the scattering efficiency. A higher scattering efficiency leads to an increase in brightness. Therefore, does it mean that this ...
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I have a question about the wording in a paper about a planetary system and comets

I was reading a paper. This is the paper: https://arxiv.org/abs/2006.01711 (https://ui.adsabs.harvard.edu/abs/2020MNRAS.496.4979D/abstract In the method section in the second paragraph there is a bit ...
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Does this galaxy resemble the Milky Way, and is it relatable as the "template" for the Milky Way?

Taking a look at this photo of comet 2I/Borisov and a background galaxy (2MASX J10500165-0152029): And compare it to this rendition of the Milky Way: The two galaxies slightly resemble each other. ...
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A comet orbits the Sun in the same plane as Earth's orbit

If the Earth around the Sun follows a practically circular orbit of radius equal to one astronomical unit, determine its orbital speed in astronomical units per year. If the Earth around the Sun ...
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9 votes
1 answer
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How do comets' nuclei stick together?

Comets are commonly called icy dust balls or dirty snowballs and as such rather light: Known comets have been estimated to have an average density of $0.6 {\rm g}/{\rm cm}^3$. Because of their low ...
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Do some comets spin? If so, how fast?

The GIF below is copied from my question earlier What might a CN filter be in the context of comet watching? Is it showing dust, or gas, or something else? where I'd said: In this post on the website ...
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7 votes
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What calculations show that Comet Shoemaker-Levy 9 orbited Jupiter for several decades before its spectacular impact? (Chodas, Sekanina & Yeomans)

This answer to A moon in eccentric orbit dipping below Roche limit includes the following about Comet Shoemaker–Levy 9 Here is a nice figure of its last passes: I looked up "fragment A" in ...
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2 votes
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Can a supernova or a close passing star create a transient sun gravity focus "habitable zone"?

This question was inspired by the previous question Would a black hole passing next to a star create a deadly focal point due to gravitational lensing?. I understand, as gravity also acts on light, ...
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6 votes
2 answers
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The creation of comets

How are comet and meteors made, and what causes them to travel through space so fast? I have tried researching, but I decided this was the faster way.
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Why do we only have one major meteor shower from 3200 Phaethon?

When talking to my son about the Geminid meteor shower tonight, we read up on 3200 Phaethon, and were curious: why is there only one meteor shower from 3200 Phaethon, and not two? Given its orbit, ...
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Are falling evaporating bodies (FEBs) and exocomets the same thing? How does one know they're falling and evaporating?

Looking for a (short) list of comets with heliocentric escape velocity I stumbled upon Wikipedia's exocoments which like exoplanets, are bound to other stars. I should have been looking for "...
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2 votes
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Why would a planet form a cometlike tail under conditions of weaker rather than stronger solar wind?

This question is prompted by one posted on the worldbuilding stack exchange: https://worldbuilding.stackexchange.com/questions/189701/could-this-planets-tail-be-visible I understand that the ionized ...
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What comet's tail did Earth pass through before Halley's?

This answer to Any record of the Earth passing through the tail (not trail) of a comet? mentions Earth passed through the tail of Halley's Comet in 1910. It caused a bit of a panic due to claims that ...
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What were they expecting to see when Halley's comet appeared in 1910?

This answer to Any record of the Earth passing through the tail (not trail) of a comet? mentions Earth passed through the tail of Halley's Comet in 1910. It caused a bit of a panic due to claims that ...
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4 votes
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Any record of the Earth passing through the tail (not trail) of a comet?

Discussion below the Space SE question How hard is it to fly through the tail of a comet? Has it been done? has led me to ask if there is any record of the Earth passing through the tail of a comet. ...
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Long-periodic sungrazers

I'm searching for long- and non-periodic sungrazing comets, like the Kirch comet of 1680 and the (meanwhile destroyed) Comet ISON. If you know a(ny) long-/non-periodic sungrazing comet(s), let me know ...
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Is there any known asteroid or comet whose path goes through the Earth?

Is there any known celestial body of at least 500 ft (150 m) diameter whose Minimum Orbit Intersection Distance (MOID) is within the Earth, meaning it's sure that it can impact the Earth? I know Comet ...
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Luminosity of Neowise

So, I have been trying to figure out the bolometric luminosity of the comet C/2020 F3 (Neowise) on the 22nd of June, 2020. At that time, Neowise was $1.4$ AU away from Earth and had an apparent ...
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1 vote
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I witnessed a steady stream of falling stars slowly falling one after another this morning. What was it? [duplicate]

This morning at 6:18am I witnessed a steady stream of falling stars that lasted at least 90 seconds from the time I noticed it. I live on a farm east of Edmonton, Alberta, Canada and the stars were ...
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Does Halley's Comet travel past the outer bounds of the Oort Cloud?

We know Halley's Comet returns every 75-76 years. We can reasonably compute its elliptical orbit. We know that the Oort Cloud is a cloud of predominantly icy planetesimals proposed to surround the Sun ...
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What is the difference between a depleted comet and an asteroid?

When a periodic comet flies by the Sun enough times, it can become depleted of its volatile elements. Once it is depleted, what distinguishes it from an asteroid, other than records of past sightings ...
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What meteor shower has the radiant that appears furthest west after sunset, and why?

When it finally gets answered, answers to How to calculate the position of a meteor shower's radiant point based on its associated comet's orbit? will help us understand why the radiant points ...
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What determines if a comet's debris will produce periodic meteor showers?

Background I was wondering if the debris from the comet NEOWISE that recently passed Earth would provide meteor showers in the future. I looked up that the Perseid meteor showers happen when the Earth ...
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Where is the Perseids meteor shower coming from?

Swift–Tuttle Comet has orbital period of 133.28 years. Yet, people say that debris and dust from this comet causes this meteor shower. This does not make any sense. Or do they want to say that from ...
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Has any of the orbiters or rover on Mars captured image of comet NEOWISE?

We are seeing stunning pictures of comet NEOWISE from earth (and ISS too), are there any pictures captured from Mars by an orbiter or rover, or any other spacecraft?
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Can a single impact event trigger a runaway greenhouse?

Somewhat related to this question: Is the Earth going to evolve towards Mars' fate or Venus' fate? Human civilization may be fragile, but life itself is extremely resilient, with extremophiles and ...
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How long can the comet C/2020 F3 (NEOWISE) will observed with the naked eye or small optics?

In the answer to the question Where should I be looking to see Neowise in southern Sweden? there is a picture with the comet positions till 30 July. In other sources I saw similar pictures also with ...
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How to calculate the position of a meteor shower's radiant point based on its associated comet's orbit?

Below this answer to Why are Delta Aquariids “for the southern hemisphere” while the Perseids are “for the north”? I wrote the comment: +1 To make this complete, ...
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