explain xkcd - User contributions [en]

Talk:3049: Incoming Asteroid

2025-02-13T00:09:27Z

172.71.241.37:

Asteroids are surprisingly destructive even at small sizes - I remember reading somewhere that the Armageddon movie asteroid was supposed to be "the size of Arlington, Texas", but that it sounded too small so they changed it to "the size of Texas" which is a drastic size increase and also proportionally far more deadly. For scale, Arlington is 250 square km and Texas is 700 000 square km. The Chixulub asteroid that wiped out the dinosaurs was between 10 and 15 km across. If it was a perfect circle, it would have an area of between 79 and 176 sq km. Arlington would be 18 km across, still within "species" range, and Texas would be 944 km across, clearly in "new moon" territory. But it _sounds_ much cooler! [[User:Zakator|Zakator]] ([[User talk:Zakator|talk]]) 22:32, 10 February 2025 (UTC)
:And that's for asteroids with normal speed (for asteroid, which is still kinda fast). The level of danger asteroid means is proportional to kinetic energy, meaning proportional to mass and SQUARE of speed, so if it's faster, it gets to extinction level even when small ... -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:29, 10 February 2025 (UTC)
:: "for asteroids with normal speed" - which is generally orbital velocity. If much faster, it would have left the solar system by now. If much slower, it has fallen into the Sun already. All objects (even Teslas) at a given distance soon have similar velocities. --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 00:04, 11 February 2025 (UTC)
::: It could be going at ''a'' speed (similar to Earth, give or take, for the sake of being on an Earth-incident orbit) and yet have such different effects. If basically following the Earth (or leading it), it'll be relatively gentle, at least before you start considering the Earth's (and the asteroid's, in the event it's significantly large) gravity well pulling it. Well, 'gentle' in comparison to one doing the 'same speed' but in the anti-orbit, for a full head-on impact. Course, that's why we need to think of velocities, and in particular the relative ones. [[Special:Contributions/172.71.241.37|172.71.241.37]] 01:31, 11 February 2025 (UTC)
:::Considering just two-body physics... Escape speed for the Sun at the distance of Earth's orbit is 42 km/s, so that's the upper limit anything is likely to be going (otherwise it's just got one shot at us). That would be something falling towards the Sun from a very large distance. If the asteroid is moving in the opposite direction as Earth, that gets added to Earth's orbital speed of 30 km/s, for a total of 72 km/s. On the other hand, Earth has an escape speed of 11 km/s at the surface, so that's the lower bound for an impact. A 6.5x factor on speed is about a 40x factor on impact energy. Which, I'm not sure exactly how that would scale devastation, but ... I'll take the low end for anything big, thanks. [[Special:Contributions/172.70.111.22|172.70.111.22]] 14:18, 11 February 2025 (UTC)
::::The upper limit is actually someting in the range of 500-600 km/s - for an interstellar object... That'd be an astronomically huge bad luck! Or should we consider an intergalactic rogue planet... -- [[User:Malgond|Malgond]] ([[User talk:Malgond|talk]]) 23:28, 11 February 2025 (UTC)
::::: ''ORRRR...'' we could go for getting crushed between ''two'' rogue planets moving at relativistic speeds in opposite directions! :-) [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 01:33, 12 February 2025 (UTC)

The 1m danger makes me think of the meteor impact that was caught on a home security camera last July in Prince Edward Island. But the Sky & Telescope article https://skyandtelescope.org/astronomy-news/hear-the-first-ever-recording-of-a-meteorite-slamming-into-the-ground/ says that it would have been only a 6-7 cm across. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 00:42, 11 February 2025 (UTC)

The sizes in the explanation are out of sync with the image. Has Randall updated it, or may it be location dependent? ~~Guest~~ 07:12, 11 February 2025 (UTC)
:I saw the comic before any explanation was put up and it was the same as it is now, all exactly powers of 10. But the labels aren't exactly at those spots, so people are probably estimating the exact point where the labels are at, though my interpretation would be that Randall meant for the labels to be attached to ranges rather than points. [[User:Tharkon|Tharkon]] ([[User talk:Tharkon|talk]]) 11:45, 11 February 2025 (UTC)
::Same here, all powers of 10. I don't think it makes any sense at all to guess at where on the axis the labels are meant to be when the labels themselves give an explicit number. The labels should probably be the ranges, eg "1cm to 10cm", "10cm to 1m" and so on.[[User:Mazz0|Mazz0]] ([[User talk:Mazz0|talk]]) 14:00, 11 February 2025 (UTC)
:::There are small markers between the labeled spots, so it's not unreasonable to estimate which marker the ellipsis points to. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 14:41, 11 February 2025 (UTC)

"Good news everyone! We were supposed to make a delivery to the planet Tweenis 12 but it's been completely destroyed!" [[Special:Contributions/162.158.94.203|162.158.94.203]] 11:24, 11 February 2025 (UTC)

It's not the first comic comparing our reaction to different scales of cosmic events, even though the asteroid "happiness level" does not peak like the supernova chart: https://xkcd.com/2878/ {{unsigned ip|172.69.195.172|21:14, 11 February 2025}}
:Indeed. This one peaks ''twice'', if taken at face value. ;) [[Special:Contributions/172.71.241.145|172.71.241.145]] 21:32, 11 February 2025 (UTC)

I'd noted that technically, when it comes to "asteroid collides with Earth" vs. "Earth collides with asteroid", neither is correct. In a centre-of-mass reference frame, the two objects collide. This was removed as "pedantry", but it seems appropriate to me. Thoughts? [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 01:29, 12 February 2025 (UTC)
:I would say if a smaller asteroid hit Earth then yes it collides with Earth. If two similar planet sized object hit each other, then I would say they collided with each other, and if Earth hit Jupiter I would say Earth collided with Jupiter. This may not be physically correct, but it is how language and meaning works. So I would say it was correctly removed. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 11:44, 12 February 2025 (UTC)

:: Yet the logic is reversed when talking about vehicles on Earth. You would say "the car collided with the bicycle" and "the train collided with the car" (or the car got hit ''by'' the train). "{Bigger object} collided with {smaller object}" in this case. --[[User:StapleFreeBatteries|StapleFreeBatteries]] ([[User talk:StapleFreeBatteries|talk]]) 23:26, 12 February 2025 (UTC)
:::Annoyingly, the standard phrase tends to be "the bike was in collision with a car", with the implication of perhaps equal fault, if not switched round entirely. Yes, a cyclist ''can'' be the one who "hits the blameless car", or pedestrian steps into the side of the passing cyclist (or car, bus, lorry, etc, potentially), but it's more often the other way round, and the balance of sympathies (regardless of who most erred, to result in the incident) should probably be considered by who is most damaged (trickier in foot vs bike incident, one is initially struck by a lump of metal with spinning bits and various hard protusions, the other may then be struck by(/strikes) the ground). [[Special:Contributions/172.71.241.37|172.71.241.37]] 00:09, 13 February 2025 (UTC)

3049: Incoming Asteroid

2025-02-11T21:17:39Z

172.71.241.37: /* Explanation */

{{comic
| number = 3049
| date = February 10, 2025
| title = Incoming Asteroid
| image = incoming_asteroid_2x.png
| imagesize = 454x570px
| noexpand = true
| titletext = The bottom ones are also potentially bad news for any other planets in our solar system that have been counting on Earth having a stable orbit.
}}

==Explanation==
{{incomplete|Created by an incoming bearer of bad news - More accurate readings of the log scale, and provide detailed explanations of each point on the chart (should probably be a table, as well). Also, add some acknowledgement of the title-text. Do NOT delete this tag too soon.}}

This comic may be inspired by the recent discovery of asteroid {{w|2024 YR4|2024 YR<sub>4</sub>}}, which, on the date of the comic (February, 10, 2025), was estimated to have about a 2% chance of striking Earth on December 22, 2032. Its size is estimated to be 40-90 meters.

This comic provides a log scale correlating the size of any incoming asteroid to whether its arrival is good or bad news. While asteroids on the smaller end of the scale are good news for sky watchers, as the upcoming objects get bigger, the potential for catastrophe grows. Many astronomy enthusiasts would be happy to see bigger meteors, as bigger generally means more exciting pictures. Of course, once the meteors grow past a certain size even the most enthusiast astronomer might grow concerned about their imminent extinction.{{cn}}

===List of sizes and consequences===
Sizes are approximate.

* '''1 cm''': Good news! Meteors are pretty!
** Nothing more than a streak in the sky.

* '''30 cm''': Great news! You might see a fireball!
** Might descend far enough for the flames of its entry to be visible with the naked eye.

* '''3 m''': Okay news, unless you have expensive windows or are very unlucky.
** Can descend far enough for the shockwave of its passing to shatter windows. The comic mockingly claims this is only a problem if your windows are expensive or happen to get directly hit by it. The {{w|Chelyabinsk meteorite}}, sitting near the upper bound of this category with approximately 18 m in size, damaged more than 7,000 buildings with shockwaves, injuring almost 1500 people.

* '''60 m''': Bad news, especially if you live near the city it's aimed at.
** The {{w|Tunguska event|Tunguska meteor}}, which flattened over 2,000 km<sup>2</sup> of Siberian forest in 1908, was 50-60 m across.

* '''600 m''': Bad news, especially if you live on the continent it's aimed at.
** Can easily cause localized extinction, and can be expected to have effects on the rest of the world as well.

* '''9 km''': Bad news for your species.
** The {{w|Chicxulub crater|Chicxulub asteroid}} that wiped out non-avian dinosaurs was about 10 km in diameter.

* '''50 km''': Bad news for your phylum.
**{{w|Chordate|Our phylum}} is primarily all the vertebrate animals.

* '''300 km''': Bad news for your biosphere.
** A global extinction event is pretty much guaranteed.

* '''2,000 km''': Good news for any life that might someday evolve on Earth's new moon.
** Earth's moon is believed to have been formed when Earth, in its infancy, was hit by an object of roughly this size. The comic assumes that another moon would form from another such impact, hypothesizes that life might evolve on that moon, {{tvtropes|BadNewsInAGoodWay|and pretends that it's good news}}.

* '''25,000 km''': Bad news for whatever planet is about to get hit by Earth.
** At this size, the "asteroid" is over twice as large as Earth itself (whose diameter is about 12,700 km) and would likely be classified as a planet. (Unofficially, at least. ''Officially,'' there would be quibbling about whether it had {{w|Clearing the neighbourhood|"cleared its neighborhood."}} Briefly. {{Citation needed}}) At that point, the comic points out, it would be more accurate to describe the Earth crashing into the "asteroid"/planet, not the other way around.

Title Text: the "bottom ones" have enough mass to change Earth's orbit. If it changed enough it might intersect the orbit of other planets (probably Venus or Mars, since those are the closest). This might lead to Earth colliding with that planet. Also, even without a collision, the changed orbit might perturb '''their''' orbits due to the Earth's gravitational force and cause negative consequences by either invoking or revoking {{w|Commensurability (astronomy)|orbital resonances}} between the various inner planets.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Header:]
:An asteroid is headed straight for Earth! That's...

:[A log scale of lengths is shown, labelled "Asteroid size", with markings of 1 cm, 10 cm, 1 meter, 10 meters, 100 meters, 1 km, 10 km, 100 km, 1,000 km, and 10,000 km. The remaining lines of text are at various points down the scale.]
:...Good news! Meteors are pretty!

:...Great news! You might see a fireball!

:...Ok news, unless you have expensive windows or are very unlucky.

:...Bad news, especially if you live near the city it's aimed at.

:...Bad news, especially if you live on the continent it's aimed at.

:...Bad news for your species.

:...Bad news for your phylum.

:...Bad news for your biosphere.

:...Good news for any life that might someday evolve on Earth's new moon.

:...Bad news for whatever planet is about to get hit by Earth.

{{comic discussion}}

[[Category:Charts]]
[[Category:Astronomy]]
[[Category:Space]]

Talk:3049: Incoming Asteroid

2025-02-11T01:31:23Z

172.71.241.37: