# What would happen if another planet (say mars) collided into earth? **URL:** \ **Category:** Factual Questions\ **Created:** [May 10, 2004, 3:35am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404 "2004-05-10T03:35:40Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![dropzone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dropzone/32/7515_2.png) [@dropzone](https://boards.straightdope.com/u/dropzone)\ **Post date:** [February 5, 2015, 11:46pm UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/21 "2015-02-05T23:46:21Z")
Read the books and saw the movie. All of them sucked. > **[When Worlds Collide](https://en.wikipedia.org/wiki/When_Worlds_Collide)** > > When Worlds Collide is a 1933 science fiction novel co-written by Edwin Balmer and Philip Wylie; they also co-authored the sequel After Worlds Collide (1934). It was first published as a six-part monthly serial (September 1932 through February 1933) in Blue Book magazine, illustrated by Joseph Franké. > Sven Bronson, a Swedish astronomer working at an observatory in South Africa, discovers a pair of rogue planets, Bronson Alpha and Bronson Beta, which will soon enter the Solar System. In eight mo... ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [February 6, 2015, 12:04am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/22 "2015-02-06T00:04:08Z")
It would be a really bad day to be a martian. ---
**Author:** ![kopek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kopek/32/337_2.png) [@kopek](https://boards.straightdope.com/u/kopek)\ **Post date:** [February 6, 2015, 1:08am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/23 "2015-02-06T01:08:26Z")
Any other votes for an extra asteroid belt? ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [February 6, 2015, 1:27am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/24 "2015-02-06T01:27:30Z")
> [@bob\_2](#): > > Obligatory Frank Sinatra quote: > > _Have you heard, it’s in the stars > Next July we collide with Mars > Well did you evah > What a swell party > A swell party > A swellegant, elegant party this is_ You mean Cole Porter quote. ---
**Author:** ![Maggie\_the\_Ocelot](https://avatars.discourse-cdn.com/v4/letter/m/df705f/32.png) [@Maggie\_the\_Ocelot](https://boards.straightdope.com/u/Maggie_the_Ocelot)\ **Post date:** [February 6, 2015, 1:35am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/25 "2015-02-06T01:35:11Z")
Both - Porter wrote it, Sinatra & Crosby duetted on it in “High Society” Dueted? Duetted? They both sang. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [February 6, 2015, 3:17am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/26 "2015-02-06T03:17:38Z")
The movie [Melancholia](http://www.melancholiathemovie.com/), by the … interesting … director Lars von Trier has the collision of the moon with Earth as its plot, and the response by a single family, led by an amateur astronomer. And by golly – spoiler alert – it collides, and the tension, denial, coping, and acceptance over the preceding days, hours , and minutes as it increases in size in the sky is beautifully played, as far as Hollywood overtheatrics and CG as could be imagined. It is truly a moving movie, with one of the best explorations of, well, melancholic depression. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [February 6, 2015, 3:56am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/27 "2015-02-06T03:56:16Z")
While there might be some orbital scenario in which the collision takes place slowly, probably the relative velocity of the rogue planet would be something like 20 miles per second, or likely more. At that speed it would only take 3-4 hours to close the distance between the Earth and the Moon. At some point during those last hours tidal forces would create titanic winds and hypertides. Every fault in the Earth’s crust would give way under the stress and there would be colossal earthquakes increasing into actual rifts in the crust exposing the mantle. Depending on your location on Earth, you would either be torn apart by hypersonic winds or volcanic eruptions, crushed under 5-mile high tsunamis, or killed by hi-G earthquake shocks. Several minutes before actual contact both planets would start fragmenting when they approached within each other’s Roche limit. The final fate of both planets would depend on how direct or glancing the collision was; in any event nothing of the Earth’s surface would remain intact and the most probable outcome is one or two incandescent balls of magma and large amounts of gas, dust and debris thrown into eccentric solar orbits. ---
**Author:** ![vomit\_comet](https://avatars.discourse-cdn.com/v4/letter/v/73ab20/32.png) [@vomit\_comet](https://boards.straightdope.com/u/vomit_comet)\ **Post date:** [February 6, 2015, 4:06am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/28 "2015-02-06T04:06:20Z")
OMG, and I get admonished for the things I post. Fucking ridiculous\>\>\>\>\>\>\>\>\>\> ---
**Author:** ![vomit\_comet](https://avatars.discourse-cdn.com/v4/letter/v/73ab20/32.png) [@vomit\_comet](https://boards.straightdope.com/u/vomit_comet)\ **Post date:** [February 6, 2015, 4:09am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/29 "2015-02-06T04:09:31Z")
So, I guess if you post in a completely hypothetical manner on a completely ridiculous post that is expecting a completely ridiculous answer, you’re all’right, but attempt to make it serious, and you’re fucked. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [February 6, 2015, 4:19am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/30 "2015-02-06T04:19:52Z")
> [@Maggie\_the\_Ocelot](#): > > Both - Porter wrote it, Sinatra & Crosby duetted on it in “High Society” > > Dueted? > Duetted? > > They both sang. I’m a writer. They get overlooked. Especially for songs. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [February 6, 2015, 4:51am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/31 "2015-02-06T04:51:43Z")
**Moderator Note** > [@vomit\_comet](#): > > OMG, and I get admonished for the things I post. Fucking ridiculous\>\>\>\>\>\>\>\>\>\> > [@vomit\_comet](#): > > So, I guess if you post in a completely hypothetical manner on a completely ridiculous post that is expecting a completely ridiculous answer, you’re all’right, but attempt to make it serious, and you’re fucked. Comments like these are not appropriate for the General Questions forum. If you want to make comments like this about a particular thread or poster, take it to the Pit. That’s what it’s for. No warning issued. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [February 6, 2015, 4:58am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/32 "2015-02-06T04:58:40Z")
> [@vomit\_comet](#): > > OMG, and I get admonished for the things I post. Fucking ridiculous\>\>\>\>\>\>\>\>\>\> > [@vomit\_comet](#): > > So, I guess if you post in a completely hypothetical manner on a completely ridiculous post that is expecting a completely ridiculous answer, you’re all’right, but attempt to make it serious, and you’re fucked. I wasted at least 25 seconds looking for something you posted here, and found none. So, correct me if I’m wrong–_not in this thread_–but you are bitching about some post(s) where you were either admonished or found yourself fucked, or both. And you dropped in here to say it? Bitching or complaints goes in ATMB or the Pit. Dropping in to just to diss a thread is a threadshit; I suppose double jeopardy applies here, but it’s not my call. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [February 6, 2015, 5:04am UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/33 "2015-02-06T05:04:27Z")
> [@Maggie\_the\_Ocelot](#): > > Both - Porter wrote it, Sinatra & Crosby duetted on it in “High Society” > > Dueted? > Duetted?.. Both, apparently. As a verb noted (heh) first in 1822. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [February 6, 2015, 1:10pm UTC](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404/34 "2015-02-06T13:10:24Z")
> [@vomit\_comet](#): > > OMG, and I get admonished for the things I post. Fucking ridiculous\>\>\>\>\>\>\>\>\>\> Not trying to pile on, but note the OP was made 11 years ago and the OP him/herself hasn’t been active for over a decade now. Any Mod admonishment of the OP now would have precious little effect. [Previous page](https://boards.straightdope.com/t/what-would-happen-if-another-planet-say-mars-collided-into-earth/244404.md?page=1)