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24 votes

Was Earth closer to Europa on 1983-11-25 or 1985-07-22?

tl;dr Miki Sudo Using JPL's SPICE toolkit, I computed the positions of Earth and Europa for the times in question. On 1983-Nov-25, Earth and Europa are 935.2 million km apart, while 1985-Jul-22, ...
lwr's user avatar
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19 votes
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Is the water underneath Europa's ice cap potable?

According to this 2007 paper, the current research as of the time of their own research had a huge range in possible concentrations of $\text{MgSO}_4$, magnesium-sulfate, with over four orders ...
zibadawa timmy's user avatar
13 votes

Was Earth closer to Europa on 1983-11-25 or 1985-07-22?

Any online planetarium or equivalent mobile app will tell you that on 1983-11-25 Jupiter was near to its conjunction with the Sun: while on 1985-07-22 it was close to opposition: So on Miki Sudo's ...
Glorfindel's user avatar
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11 votes

How can "Geysers" on Europa reach heights of 100km?

Technically those aren't "geysers" on Europa, they're cryovolcanos. Though that definition may be a bit imprecise as well, but the 100 km eruptions on Europa probably have more in common with ...
userLTK's user avatar
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11 votes
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How does gravity affect pressure under water?

For a liquid, hydrostatic pressure is $\rho g h$ where $\rho$ is density (this is always the same for all water) g is gravitational acceleration and h is depth. The gravitational acceleration on ...
James K's user avatar
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10 votes
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What is the underwater temperature of Europa?

No, nothing on Europa could possibly be photosynthesizing as we know it. Jupiter doesn't emit light, and what it reflects from the sun is not enough, plus there's no significant amount of carbon ...
Nathanael Vetters's user avatar
9 votes
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Why the Circumstellar Habitable Zone is defined as it is, if life could be possible outside of it?

From your first link, the definition is: "The circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support ...
Rory Alsop's user avatar
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8 votes
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How much light would be reflected from Jupiter to Europa (in Europas night)?

It's a pretty straight forward calculation of 3 factors. Distance from the sun, apparent size and albedo. I'm going to compare Jupiter to our full moon, since we're all familiar with that. ...
userLTK's user avatar
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7 votes

How can "Geysers" on Europa reach heights of 100km?

I wanted to throw my hat into the mix to flesh out another contributing factor. One reason these "geysers" are so capable of achieving great heights is a lack of atmosphere on Europa to slow them down ...
zephyr's user avatar
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7 votes
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Is Jupiter's rotation slowing?

Yes Tidal locking is a mutual process, and both the satellite and the parent body will eventually permanently face each other. However, while tidal locking of a satellite can happen relatively ...
SE - stop firing the good guys's user avatar
7 votes
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What are these bumps on Europa?

The paper Geometry and spatial distribution of lenticulae on Europa gives a good description what is going on. As I mention in my comment the bumps/domes are called lenticulae, Latin for freckles. In ...
Fred's user avatar
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6 votes

Is the water underneath Europa's ice cap potable?

Since water on all planets is in contact with impurities, I would think that the default for water is salty, and a small percentage on Earth (2.5%) gets desalinated by going through the evaporation/...
antlersoft's user avatar
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5 votes

Is the water underneath Europa's ice cap potable?

The most popular hypothesis for explaining the various zigzagged lines (lineae) that cover Europa’s surface is that they are caused by cracks appearing in the ice shell because of tidal deformations, ...
Pierre Paquette's user avatar
5 votes

Is Jupiter's rotation slowing?

Nope. (Sorry, the other answer beginning with yes, I wanted to begin one with no), but both answers are correct from a certain point of view. Jupiter's rotation is speeding up because it's ...
userLTK's user avatar
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4 votes

Icy moons: why hasn't the ice sublimated away?

I'll pick up on your example as it can be used very well for illustrating the main points: First: The solar intensity in Jupiters orbit is less than 4 percent compared to Earths. So much less energy ...
CKA's user avatar
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4 votes
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The orbital period of Jupiter and Europa billions of years later

When the Sun becomes a red giant there will be some mass loss, making Jupiter's orbit wider and slower. The extent is fairly small during the initial expansion, but about 50% of the mass at the end. ...
Anders Sandberg's user avatar
3 votes
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Jupiter's effect on a hypothetical "warm" Europa's water

If Europa was the only large moon orbiting Jupiter then it wouldn't have tides, or, more accurately, it would have a permanent tidal bulge and no moving tides, so it depends on what you call a tide. ...
userLTK's user avatar
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3 votes
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How thick is the ice on Europa?

From this NASA FAQ page about Europa: Theory and observation indicate that Europa's icy shell is around 15 to 25 kilometers (10 to 15 miles) thick, overlying an ocean approximately 60-150 kilometers (...
sforsingh's user avatar
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3 votes
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Is there enough light to grow plants in the ocean of Europa?

The surface of Europa gets some sunlight direct from the sun and some long wave radiation from Jupiter so it's not in darkness. It's also in Jupiter's radiation belt so it gets hit with high energy ...
userLTK's user avatar
  • 24.1k
3 votes

Enceladus; why use the words "geysers", "jets", and "plumes" interchangeably?

A geyser is a water volcano, they are familiar and fairly common on Earth. By analogy, a water volcano on other planets can also be called a geyser, although the mechanism may be rather different. ...
James K's user avatar
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3 votes

Enceladus; why use the words "geysers", "jets", and "plumes" interchangeably?

Question: I would know why the words "geysers" and "jets" would be used interchangeably. Is this because it hasn't been confirmed yet what they are, and the authors don't wish to ...
StephenG - Help Ukraine's user avatar
2 votes

Determine the moons of Jupiter through a telescope

The one far away is Ganymede, the brightest is Europa but not much of a way for the others (from any angle) I did find a diagram that lines up pretty well with your picture though.
Homework Researcher who helps's user avatar
1 vote
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How can "Geysers" on Europa reach heights of 100km?

I've drawn information from the helpful links below this question and this partial answer I don't think astronomers or planetary scientists expect a geyser of liquid water to be squiring 100 to 200 ...
uhoh's user avatar
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1 vote

Determine the moons of Jupiter through a telescope

You can use Sky and Telescope's interactive tool for observing Jupiter's moons. This website describes how to use it to determine the positions of the Galilean moons. It works in the past or future.
Nagarjuna Borra's user avatar

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