Next best planets for life?

Question

I need the top three planets that would be best to support life.

I already know of Europa, Jupiter's moon, but what other two planets would be next best to support life?

Thanks!

I know Europa is not a planet.
I meant like what planets OR MOONS, could support life.

Answer 1

Europa ties with Mars; liquid water, organics and an energy source (geothermal). We should be looking a lot closer at Europa... but Mars is much easier to get to, we need nuclear propulsion. Next I would say Enceladus, a tiny moon of Saturn, which also has the 3 requirements... probably. Ganymede and Callisto have oceans 100 miles under the ice crust surface... but what energy soources? A long shot would be Titan although its pretty cold there; it would have to be "life as we dont know it" and use something else besides water as a liquid solvent. The dark horses would be Venus (in the clouds 50 miles up) and Io which has a lot of energy sources; again life as we dont know it. And there is always the Jovian planets which have huge atmospheres with clouds that have Earth-like conditions of temperature and pressure.. but can life form in a gas or does it need a liquid (ocean)? I suspect life is pretty much everywhere there is (1) liquid water (2) organic carbon-based chemistry happening (food) and (3) an energy source life can utilize for metabolism.

Answer 2

Titan, the largest of the moons of Saturn is one. Titan has an atmosphere largely made up of nitrogen, with less than one percent of methane. The surface pressure of Titan's atmosphere is higher than that of Earth, but the temperature is extremely cold. A rich assortment of organic molecules is found in Titan's atmosphere, as products of the ammonia/methane chemistry. The mixture includes hydrogen cyanide, a compound in the path to the synthesis of amino acids. This finding has led to speculations that primitive life forms might be present. The low temperatures on this satellite make it unlikely.

Answer 3

This question is a topic that is being debated in science today.

In relation to your question, Europa is not a planet, but a moon. Thus it does not qualify as an answer to your question.

To determine an answer to your question, one must use the single planet that has life as a reference at the moment. This is poor science, but since we have no other reference we are stuck using this method.

Using boundaries of a class of lifeforms known as archaea, you may set up the boundaries where life is known to exist in the extreme.

Temperature wise, thermophiles and hyperthermophiles can live in temperatures from 60-121C, which is really hot. Meaning that if you look up planets, as long as their mean temperature does not exceed 121C, the possibility for life exists. Here I list these planets: Mercury, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto

Now let's look at Cryophiles. These are life forms that like it cold, really really cold. They typically are found on Earth in 15C or lower weather. That means that any of the cold planets listed above such as Uranus, Neptune and Pluto could still support life.

So now the task is to find life that needs little water, a lot of acid or a lot of base and so on. As you find planets that exceed these extremes in all cases, one can eliminate them from the list of planets with potential sources of life.

I listed an excellent link to find an extremophile article. You can perform the exercise yourself if you would like. The results are gratifying and very informative.

In the end you will learn that life has a wide range of extremes and could really be found almost anywhere in the solar system. I would point out that the extremes allow you to say life can live there, but like everything else if the environment makes it easier, than you will more likely find life there.

Mars is of course a very interesting target for hunters of life. It is a rather moderate planet. The storms (while dangerous to humans) would be of no real concern to microbes, especially if they are underground. There may be water there, which is a known requirement for life on Earth. Mars is an excellent candidate for life outside of Earth.

Mercury has problems. Although Mercury cannot be completely eliminated, the environment is harsh. Water is likely boiled away, the pressure is very low and the temperature fluxuations are so drastic that life would have a hard time getting a foothold to survive there.

Venus is extremely hot. However there is speculation that Venus may be able to harbor life higher in its atmosphere. However that would mean that life would need to perpetually float in that "safe" zone. Stray too low and you would boil away in temperatures hot enough to melt lead. Go to high and toxic chemicals and low pressure may disrupt whatever chances you have.

Jupiter is likely not a good place (although some scientists believe floating creatures could make a home in the atmosphere similarly to Venus, see Cosmos with Carl Sagan I believe he references it in his documentary). Europa is a moon, but with lots of potential water. However being a moon means that it is disqualified from being an answer. Similarly Saturn, Uranus, and Neptune are like Jupiter. So unless life can float and live in extreme cold (not to mention rain made from diamonds) they are not good answers either. Their moons do not count as answers same as Europa.

Pluto is within the acceptable temperature range and thus could potentially harbor life. However recently an internation group of scientists have disqualified Pluto as a planet and thus it does not count as an answer either.

Therefore your two best answers are currently the inner rocky planets ordered in the following way.

1.) Mars - There is water and a somewhat calm environment

2.) Venus - There are potential safe zones for life high in the atmosphere.

3.) Mercury - Not likely, but certain extremophiles may be able to survive.

Remember also that we only know what life is like on Earth. Scientists are well aware that life on other planets may be something we do not recognize or even identify as life. There is a possibility that as we learn to travel to other planets we will begin using resources to help us out and then learn later on that we are killing living creatures without knowing it.

Answer 4

Europa is not a planet. But Mars and Nibiru already have life and if they don't, it is strongly possible for them to support life.

Answer 5

according to my knowledge, Mars is a strong candidate because of the climate and temprature, but still there should be enough amounts of water to support life.