What is the difference between the earth atmosphere and that of other planets?

Question

What is the difference between the Earth's atmosphere and that of other planets (Mercury, Pluto, Mars, Venus) that humans don't make "blopp".
Seriously. I mean, on what gases is a human dependant to survive for at least .. say ...0.001 second? On whitch of those planets you can say that there is no vacuum? And what role plays density for that matter?

Actually it's more a question NOT about "is life possible" it's about SUPPOSED an astronaut looses his helmet on one of these planets how long could he survive? .. if ever =)

Answer 1

Oxygen is the gas on which human respiration is dependant. There is a relative abundance of this gas in our atmosphere. Plants (which arrived on Earth before animals) were responsible for "polluting" the primeval atmosphere with this highly reactive gas (incidentally the same gas which forms ozone and screens us from deadly high energy radiation from the sun).

I'll quickly run through the rest of the planets: -

1. Mercury.
Helium atmosphere which is almost nonexistent. Surface temperatures vary between 350C (day) and minus 170C (night).
Verdict: - instant death.

2. Venus.
Atmosphere has large quantities of sulphur dioxide (which smells like rotten eggs or a really bad fart!) and a constant rain of sulphuric acid. Pressure 90 times greater than the Earth's. Temperature of about 500C. Suspected that this is the effect of runaway global warming (heat trapped by carbon dioxide).
Verdict: - Instant nasty death. The closest physical approximation to Hell.

3. Earth.
Mmmmm. Nice.

4. Mars.
Atmosphere of mainly carbon dioxide. Atmospheric density fluctuates, but is never enough for liquid water to form in appreciable amounts. Mean surface temperature about minus 27C.
Verdict: - Temperature and gravity are within tolerances for human life, but needs an oxygen and water transplant. No go (for the present).

5., 6., 7., and 8. Jupiter, Saturn, Uranus and Neptune.
These are all termed "gas giants". They all have cores, but at depths within their atmospheres such that surface pressure is enormous. Temperatures of between minus 150C (Jupiter) and minus 220C (Neptune).
Verdict: - All non-starters.
As a piece of trivia, Saturn is the only planet which is less dense than water, which means that if you could find a big enough basin of water, it would float!

And finally (phew!) 9. Pluto.
Smaller than the moon. No atmosphere. Surface temperature minus 230C.
Verdict: - Waste of time and space. Not even worth the term "planet". There are bigger moons than this! Ours for a start!

The combination of a planet's density and size affect its gravitational attraction. If Earth were denser or larger, its gravitational attraction would increase (ie// you'd weigh more).
Mercury is about the size and density of the moon, so you could probably jump about 10-20 feet in the air quite easily. Mars is less dense but larger than Mercury, and has comparable gravity. Venus is about the same as Earth. Jupiter isn't dense, but could hold about 1,000 Earths, so its gravity is too high for us. The other gas giants, for all their size, are appreciably less dense than Earth, and have gravities not much greater than Earth. And Pluto's so small and insignificant that I reckon if you jumped you could possibly end up in orbit around it.

Earth is the ONLY place in the entire Universe that we know of which has conditions which can sustain life of any sort. If we play a part in altering the atmosphere on this planet the Earth will still exist.It just might not be suitable for life.

Further answer to your additional response bit: -

If an astronaut removed his helmet on any planet except Earth he would die almost instantly.

Answer 2

i ) As already mentioned in other posts, Earth's atmosphere contains oxygen. It is worth noting that it also contain nitrogen and carbon dioxide.
2 ) Mercury is for all practical purposes a world without an atmosphere, although it does have out-gassing.
3) Mars does have a very thin atmosphere of CO2. Although, at the equator in the summer the temperature is about 70 F that only extends to about an inch. Above that, you freeze.
4 ) Pluto may have an atmosphere??? But there is no real hard data to go on.

Answer 3

There is another problem besides our "chemical" need for oxygen. There is an issue of the "physical" strength of our tissues.

The human lung cannot withstand an abrupt change in atmospheric pressure. This is the cause of various injuries and fatalities in SCUBA diving. Such as an "air embolism" the expanding gases in the lungs stretch, and then rupture the thin walls of the aveoli (air sacs) in the lungs. Air bubbles enter the blood, continuing to expand. This air disrupts blood circulation, and can be similar to a stroke.

I was told that this can occur in as small a change as 4 feet of water depth.

I do remember science fiction stories being set on one of Jupiter's moons, but these stories were probably written in the pre-Voyager days, and I don't remember whether the humans lived under pressure or not.

So the large planets would crush us, while the small planets would explode us.

I don't know if our eyes would pop out like in "Total Recall" though.

Answer 4

The most unusual feature of the Earth's atmosphere is that it contains oxygen, a highly reactive gas. As far as we know, the presence of oxygen in a planet's atmosphere is a sure sign that there is life. No process that we know about, other than photosynthesis, produces it. If there weren't any plants continually renewing it, all the free oxygen in our atmosphere would long ago have combined with other elements in the Earth's crust. The same applies to other reactive gases. If we ever discover a planet with free fluorine in its atmosphere, it will be a safe bet that there's some form of life present.

Answer 5

Earth has an atmosphere, some other planets don't. Earths atmosphere is made up of oxygen, hydrogen, nitrogen and, I think, quite a lot more gases. Other atmospheres have only one or two gases where there is an atmosphere, for example, I think Mercury's atmosphere is made up mainly of nitrogen, I might be wrong though but that's the difference

Answer 6

Titan, as hymn says, has nitrogen 98.4%, If plant life were introduced by colonists the oxygen percentage would rise,

Titan is the only known moon with a fully developed atmosphere that consists of more than just trace gases. The presence of a significant atmosphere was first discovered by Gerard P. Kuiper in 1944 using a spectroscopic technique that yielded an estimate of an atmospheric partial pressure of methane of the order of 100 millibars (10 kPa). Since that time, observations from Voyager space probes have shown that the Titanian atmosphere is denser than Earth's, with a surface pressure more than one and a half times that of our planet.

the remaining 1.6% composed of methane and only trace amounts of other gases such as hydrocarbons (including ethane, diacetylene, methylacetylene, cyanoacetylene, acetylene, propane), argon, carbon dioxide, carbon monoxide, cyanogen, hydrogen cyanide and helium. The hydrocarbons are thought to form in Titan's upper atmosphere in reactions resulting from the breakup of methane by the Sun's ultraviolet light, producing a thick orange smog.

The findings of the Huygens probe indicate that Titan's atmosphere periodically rains liquid methane and other organic compounds onto the moon's surface.

The presence of argon 40 was also discovered in the atmosphere, evidence of cryovolcanism producing a "lava" of water ice and ammonia.

Later, a methane-spewing volcano was spotted in close-up images, and Titanian volcanism is now believed to be a significant source of the methane in the atmosphere; previously hypothesized methane oceans now appear to be virtually absent.

The October 2004 Cassini flyby photographed bright, high clouds at Titan's south pole, but they do not appear to be methane, as had been expected. This discovery has baffled scientists, and studies are currently underway to determine the composition of the clouds and decide whether our understanding of Titan's atmosphere needs to be revised.

Answer 7

i read all the other answers, you got a lot of correct info. one thing i would add is that a moon of Saturn, Titan, is the only other atmosphere in our solar system that has a nitrogen atmosphere like earth. (Earths atmosphere is called a Nitrogen atmosphere because it's like 75% nitrogen). But Titan is way too cold for life as we know it. A lake feature has been identified on Titan so theres probably active atmoshperic stuff going on like on earth, rain, clouds, storms.
When one talks about atmosphere one is talking about gas that is held close to the planet/moon by gravity. Jupiter and saturn are basically atmospheric planets, their significant features are due to gasses. There's nine planets and around sixty moons in our sun system. i think only around seven or eight or so have atmospheres of any significance.

Answer 8

Well the 1st thing the difference between the earth atmosphere &that of the others is that the earth's atmosphere contains oxygen.The earth is the only planet containing oxygen.and aiso our atmosphere is less dense than the others.The other point here is that the more one's atmosphere is dense it becomes more difficult to survive.Mainly a human being is dependant on oxygen.

Answer 9

Think of it like this: Jupiter is 98.7% gas and 2.3% rock. The little amount of rock is the core.Jupiter's atmosphere is ALOT thicker than Earth's. If you take Jupiter and Earth and put them together, It would be 0.1% bigger. So the difference is size and mass buy HUGE amounts.

Answer 10

The Earth's atmosphere has oxygen (20%).