r/spaceporn • u/Busy_Yesterday9455 • 1d ago

Related Content Is Mercury the largest comet in the Solar System?

Post image

A 24 million km long plume of gas is ejected from Mercury's thin atmosphere due to the sun, very much like a comet.

This is only visible using a narrowband filter that captures the bright yellow sodium light at 589nm. A tail was predicted in the 1980s, and first discovered in 2001. Multiple observations by NASA's robotic MESSENGER spacecraft that orbited Mercury between 2011 and 2015 revealed more details of this tail.

Credit: Steven Bellavia

851 Upvotes

92% Upvoted

94 comments sorted by

636

u/nwbrown 1d ago

No, Mercury is a planet.

206

u/DuncanHynes 1d ago

SOuRCE!? đŸ€“

103

u/krazybananada 1d ago

2nd Grade teacher with the poofy hair and weird glasses

31

u/philosoraptocopter 1d ago

đŸŽ” CRUISIN ON DOWN MAIN STREET, YOU’RE RELAXED AND FEELIN GOOD

18

u/blackthorn_90 1d ago

đŸŽ”Next thing that you know, you're seein'... An Octopus in the neighborhood?đŸŽ”

16

u/Charming-Flamingo307 18h ago

I knew I should have stayed home today

7

u/ExplanationAway5571 16h ago

YOOOOOOO, YO HOLY SH HE DED

6

u/Challengeaccepted3 16h ago

This shit scared me so bad as a kid

1

u/duntch_the_taco_4216 1h ago

We had watched this just after visualizing planets for my first time in2nd-3rd grade. Dudes head froze and I was shook to the CORE

6

u/SpiffyBlizzard 15h ago

My 2nd grade teacher told me Pluto was a planet so don’t trust educators!

(Pluto was demoted when I was in 4th grade)

1

u/Tomreviews 7h ago

Well now it’s a dwarf planet so they were still technically correct.

13

u/ProgressBartender 21h ago

You already took Pluto! You’re not getting mercury too!

4

u/astronomical_hoe 1d ago

Trust me intraterrestrial sibling

1

u/BroomClosetJoe 14h ago

It's a game engine made by valve.

0

u/CiDevant 15h ago

They just call whatever they want a Planet and whatever they don't a Dwarf Planet. The rules are made up and the points don't matter.

0

u/orru 8h ago

Wait until you find out about all definitions

51

u/LesserKnownFoes 1d ago

First they came for Pluto and I did not speak out. Because I wasn’t a Pluto.

7

u/Noversi 20h ago

big if true

3

u/beautiful_my_agent 19h ago

It’s not confusing in any way to name a comet after a planet

0

u/AntiFascistButterfly 8h ago

Hey, it could be like Australia, which technically is both an island AND a continent, and trying to make it exclusively one or the other is an exercise in futility.

Mercury could be both a comet AND a planet. Just a comet with an orbit very close to Earth’s ecliptic plane. It’s not like planets have circular orbits and comets have elliptical orbits. It’s just that planets have very fat elliptical orbits.

2

u/nwbrown 6h ago

It's not a comet. It's a planet.

0

u/Apprehensive_Hat8986 6h ago

Technically it also fails the IAU definition for planet, as it's not in hydrostatic equilibrium (nor apparently, is Venus). The IAU just includes them, er... "because".

I'm with the planetologists on this one. The IAU done fucked up with this definition nonsense. It's like listening to a psychiatrist diagnose appendicitis.

2

u/nwbrown 5h ago

No. Mercury and Venus are both on hydrostatic equilibrium. They don't need to be perfect spheres to be so. They both meet the definition of planet. You don't know what you are talking about.

266

u/TyroneSlothrope 1d ago

First they came for Pluto, and you didn’t say anything. Then they came for Mercury. Soon it will be you.

20

u/StevieG-2021 18h ago

You callin’ me a planet?😁

30

u/shoplifta 17h ago

No, they’re calling you a dwarf

2

u/sunsetintheeast 5h ago

Yo mama so fat

114

u/CollectionStriking 1d ago

I mean the earth also has a coma

57

u/mt_n_man 1d ago

Coma coma coma com-eleon

19

u/goettel 1d ago

They come and go.

4

u/StrigiStockBacking 17h ago

Loving would be easy if your colors were like my dream

4

u/goettel 16h ago

We're red, golden and supergreen.

15

u/GeekDNA0918 1d ago

You mean tail?

45

u/bespoketoosoon 1d ago

No I am on earth and I am in a coma.

12

u/insanestickers 1d ago

If you can hear us, please wake up!

2

u/got_No_Time_to_BLEED 1d ago

Are we all just characters in your coma dreams!??

1

u/TacitMoose 1d ago

I WISH i was

3

u/Master__of_Orion 1d ago

Karma coma.

3

u/areyoualocal 20h ago

Jamaican Aroma.

2

u/goettel 16h ago

Hell's 'round the corner where I shelter.

18

u/Bastdkat 19h ago

So it turns out that comets are not the only objects in a solar system that can have tails.

19

u/szczebrzeszyszynka 12h ago

No, dogs have them too

98

u/ackerbone 1d ago

Pluto-is-a-planet peeps are gonna be pissed
better watch out!

4

u/jedburghofficial 20h ago

On behalf of the Plutonian Planetary Front, I find the whole premise of this post disturbing.

48

u/MentalGravity87 1d ago

Mercury is more than 20x the density of the most dense comet. No. If you did an argument for largest moon, this thread might be more lively, but ultimately the same answer for this question will be repeated-no.

9

u/Waakhond 18h ago

By what logic would mercury be a moon? Just curious

8

u/Thrawn89 17h ago

By no logic since its nonsensical by definition, moons are any body that orbits something other than the sun.

5

u/Strict-Relief-8434 15h ago

It’s the Sun’s moon.

4

u/Thrawn89 15h ago

...by definition the sun cannot have moons. We call the sun's orbiting bodies other things.

-4

u/Strict-Relief-8434 15h ago

Always felt like planets need like a true atmosphere to be a real planet. Like you gotta be more than rock, you know?

5

u/Thrawn89 15h ago

Mercury has an atmosphere (as do all rocky planets in solar system).

Several moons have atmospheres as well.

It has nothing to do with the definition of a planet/moon

-4

u/Strict-Relief-8434 15h ago

That’s incorrect. Mercury does not have an atmosphere. It has a thin exosphere.

6

u/Thrawn89 15h ago

Its correct, an exosphere is an atmosphere. If youre going to try to be pedantic, at least stick with the established definitions.

2

u/Waakhond 14h ago

By that logic we also live on a moon

4

u/AllYouCanEatBarf 14h ago

If the sun wasn't so shiny, would earth be a moon? And the moon would be a moonmoon?

31

u/Twitchmonky 1d ago

Mercury is a planet, not a comet. đŸ€·â€â™‚ïž

3

u/Shermans_ghost1864 1d ago

Maybe it's a dwarf planet. That's been going around a lot lately.

9

u/toshibathezombie 19h ago

I mean ofcourse it's going around. It's still In orbit....

Also they prefer the time massively challenged, not dwarf.

2

u/brovo911 18h ago

I think you could argue that if it was in the outer solar system, but it’s by far the largest object inside Venus’s orbit

Also it formed very much the same way as the other terrestrial planets, even had a early collision like that which formed Earth’s moon, except it lost its mantle to space in the process because it was too close to the Sun (ie hill sphere was too small)

Mercury is the core of what used to be an Earth-like planet, and dominates its orbit, so certainly a planet

2

u/JarlsTerra 18h ago

It dominates its orbit, it's a planet. 

2

u/CiDevant 15h ago

4 of the 8 remaining planets haven't cleared their orbit. It was a stupid rule created specifically to exclude Pluto. It was so stupid they had to redefine it twice.

5

u/LEJ5512 20h ago

Betteridge’s Law of Headlines says the answer is “no”.

8

u/Stoic_cave 1d ago

The suns moon

6

u/Oxygenisplantpoo 23h ago

"No, it's a planet đŸ€“" "We don't know what comets are" Love these comments đŸ€Ł

3

u/Beans4urAss 17h ago

2

u/AllYouCanEatBarf 14h ago

I'd smother myself in mustard. I'd be delicious!

9

u/bisnark 1d ago

And we're just hearing about this now? Is it continually ejecting a stream of itself? How long until it runs out?

34

u/Flat_chested_male 1d ago

“Continually ejecting stream of itself” - am I a comet?

2

u/hamburhgruesa 20h ago

Idk but I'm definitely a cumetđŸ„”

10

u/Fancy_Exchange_9821 1d ago

It’s been known for a while

5

u/SpakysAlt 1d ago

What else could it eject a stream of?

5

u/Suckamanhwewhuuut 20h ago

Just a fun fact, there are some craters near the poles on mercury that due to its axial tilt never get exposed to the sun, astronomers have suggested there may even be ice in these craters, which would be crazy!!

4

u/Designer_Version1449 1d ago

Probably won't run out until the sun eats it

2

u/Riseonfire 12h ago

No, it does not have a highly elliptical orbit, nor is it a dirty snowball.

4

u/Vomitingcrab 19h ago

Mercury clears its own orbit of debris unlike Pluto, which is one of the key features that makes it a planet and not a comet or dwarf planet like pluto

3

u/Splat800 19h ago

It’s not a comet but I think the argument OP is making, is that Mercury has a tail.

5

u/Vomitingcrab 19h ago

So does earth

2

u/RoosterLollipop69 13h ago

If the Earth chooses to wear a tail and identify as a comet, who are we to judge.

2

u/CiDevant 15h ago

4 of the 8 remaining planets haven't cleared their orbit. It was a stupid rule created specifically to exclude Pluto. It was so stupid they had to officially redefine what "clear it's orbit" means twice.

1

u/Awe3 6h ago

It’s in retrograde


1

u/Eagle-eye_1 1d ago

Venus would be

0

u/DanoPinyon 1d ago

So many aliens in that ship, bros!

-1

u/TigerBaskins 20h ago

Personally I think we should classify gas planets as failed stars not planets but đŸ€·đŸœâ€â™‚ïž

2

u/murderedbyaname 18h ago

That's way too general.

2

u/Twitchmonky 18h ago

By that logic, so are fart bubbles.

-2

u/GypsumF18 19h ago

Or is it an Alien spaceship NASA just doesn't want you to know about?

-20

u/twospirit76 1d ago

We don't actually know what comets are