Questions tagged [planets]

Celestial body that orbits following an elliptical path around a star or stellar remnant.

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94 votes
4 answers
12k views

If Earth had rings?

If Earth had rings, would they center on the equator like Saturn's rings do on its equator?
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78 votes
6 answers
9k views

How can we see planets thousands of light years away but don't know if there are more planets in the solar system?

That is basically my question, it arose when I saw an article (here is the scientific paper, which should be free to read) saying two Caltech scientists might have found the 9th planet of the solar ...
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71 votes
5 answers
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Is there a small enough planet or asteroid you can orbit by jumping?

I just had this idea of orbiting a planet just by jumping and then flying upon it on its orbit kind of like superman. So, Would it be theoretically possible or is there a chance of that small body to ...
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55 votes
4 answers
136k views

How does gravity work underground?

Would the effect of gravity on me change if I were to dig a very deep hole and stand in it? If so, how would it change? Am I more likely to be pulled downwards, or pulled towards the edges of the hole?...
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45 votes
2 answers
8k views

Does a star need to be inside a galaxy?

Must a star belong to a galaxy, or could it be completely isolated? In case it can be isolated (not belong to a galaxy), could it have a planet orbiting around it?
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41 votes
8 answers
77k views

If the gravity at the center of the Earth is zero, why are heavy elements like iron there?

If gravity is zero at the center of the earth, why is there a core of heavy elements, such as iron? Alternate question for the opposite hypothesis: If gravity is greatest at the center of the earth,...
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39 votes
12 answers
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If gravity disappeared, would Newton's third law make everything that was pressed to the ground by gravity get pushed upwards? [closed]

If gravity disappeared, would Newton's third law make everything that was pressed to the ground by gravity get pushed upwards?
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39 votes
5 answers
33k views

Would you be weightless at the center of the Earth?

If you could travel to the center of the Earth (or any planet), would you be weightless there?
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38 votes
6 answers
90k views

Why don't planets have Circular orbits?

This might be a completely wrong question, but this is bothering me since many days ago. Given the mass (Sun) curves the space around it, gravitation is the result of such curved space (Correct me if ...
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35 votes
6 answers
13k views

Could there be a star orbiting around a planet?

I wonder if there ever could be a star (really small) which may orbit around a planet (really big)?
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33 votes
2 answers
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Why does the Earth even have a magnetic field? [closed]

From my knowledge of magnetism, if a magnet is heated to a certain temperature, it loses its ability to generate a magnetic field. If this is indeed the case, then why does the Earth's core, which is ...
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33 votes
3 answers
7k views

Is there a maximum distance from a planet that a moon can orbit?

Given a planet that orbits a star, and a moon that orbits that planet, is it possible to define a maximum orbital radius of that moon, beyond which the moon would no longer orbit the planet, but the ...
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32 votes
3 answers
9k views

Why does the Moon face Earth with the same side?

I know that the rotation period of the moon equals its revolution period. It's just so astonishing that these 2 values have such a small difference. I mean, what is the probability of these 2 values ...
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32 votes
1 answer
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Using nuclear devices to terraform Mars: Elon Musk's nuclear proposal? [closed]

Elon Musk has recently suggested Using nuclear devices to terraform Mars. In the past, comet related ideas were mooted, but Musk seems, to me anyway, to be a man in a hurry and perhaps his idea has ...
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31 votes
6 answers
6k views

Does bottle water rise a little bit on full moon days?

High tides and low tides are caused by the Moon. The Moon's gravitational pull generates something called the tidal force. The tidal force causes Earth—and its water—to bulge out on the side closest ...
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31 votes
3 answers
5k views

When a planet is heated through gravitational pull, where is the energy taken from?

Jupiters moon Io is heated through the gravitational pull of Jupiter, but when Io is heated because of this, where does that energy come from? How does conservation of energy work for this effect, ...
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31 votes
3 answers
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Why do the planets' orbital distances fall on an exponential curve?

Background: I was recently reading a book on the planets to my son and I noticed a pattern in the distributions of the planets. The planets' distances roughly follow an exponential distribution. ...
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30 votes
3 answers
7k views

What nonlinear deformations will a fast rotating planet exhibit?

It is common knowledge among the educated that the Earth is not exactly spherical, and some of this comes from tidal forces and inhomogeneities but some of it comes from the rotation of the planet ...
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29 votes
3 answers
4k views

Is a westward flying plane heavier than an eastward one?

I understand that you weigh less at the equator due to the increased centrifugal force. From my understanding, the faster you circle the Earth, the less your effective normal force you would feel, up ...
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28 votes
3 answers
23k views

Is Jupiter a failed star?

In my physics lessons, my teachers have always been keen to tell my class that Jupiter is considered a 'failed star' by scientists. Is this true? In my own effort I wondered if maybe this could just ...
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27 votes
6 answers
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Does gravity get stronger the higher up you are on a mountain?

So I saw this article stating that gravity is stronger on the top on the mountain due to there being more mass under you however I have read some questions other people have asked and most of the ...
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27 votes
2 answers
10k views

How long until we fall into the Sun?

As a planet moves through the solar system, a bow shock is formed as the solar wind is decelerated by the magnetic field of the planet. Presumably the creation of this shock wave would cause drag on ...
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27 votes
1 answer
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The transit of Venus and solar neutrino rates

The following question was posed at the end of Maury Goodman's June 2012 long-baseline neutrino newsletter. During the Venus transit of the sun, were more solar neutrinos absorbed in Venus, or ...
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26 votes
3 answers
4k views

Why do the storms of Jupiter have long life unlike that of Earth?

Recently I saw How the Universe Works. In one of the episodes, concerning Jupiter, they told that the storms on Jupiter can survive many, many, times longer than those on Earth. What is the reason ...
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25 votes
9 answers
28k views

Why are orbits elliptical? [duplicate]

Almost all of the orbits of planets and other celestial bodies are elliptical, not circular. Is this due to gravitational pull by other nearby massive bodies? If this was the case a two body system ...
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25 votes
1 answer
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Causes of hexagonal shape of Saturn's jet stream

NASA has just shown a more detailed picture of the hexagonal vortex/storm on Saturn: http://www.ibtimes.com/nasa-releases-images-saturns-hexagon-mega-storm-may-have-been-swirling-centuries-1496218 ...
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24 votes
11 answers
11k views

Backyard experiments to falsify the Flat Earth theory [duplicate]

I recently became aware that the flat Earth theory still exists in the 21st century, and has colored the views of a friend of mine. Roughly speaking, the tenets are: The Earth is a flat disk, with ...
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24 votes
8 answers
5k views

Can we cool Earth by shooting powerful lasers into space? [closed]

In a sense, the climate change discussion revolves around the unwanted warming of the earth's atmosphere as a whole. It seems a bit too obvious to be true, but could we cool the atmosphere by simply ...
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24 votes
6 answers
4k views

What would the collision between a (large) solid planet and a gas giant be like?

Assuming a Jupiter-like planet and an Earth-like planet (Except, say... half the mass of Jupiter), what would happen when the two collide? For clarification: What would the actual collision be like? ...
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23 votes
2 answers
2k views

How deep is the Great Red Spot?

The Great Red Spot (GRS) is a very persistent storm system that's easily visible through a telescope on the surface of Jupiter. But what is the three-dimensional structure of the GRS, and how deep ...
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22 votes
8 answers
4k views

For Newton's gravitation equation, how do you account for planet size?

My daughter was doing a physics problem where she had to calculate the gravitational force of an object that was 250 km above the earth... She used the equation: $$F=\frac{G\cdot m_1 \cdot m_2}{r^2}$$...
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22 votes
6 answers
7k views

Can the average length of the day and night of a planet be different?

At one point in "Marvel's Agents of S.H.I.E.L.D.", some agents are on a planet where the day, defined as the length of time where the sun shines on the planet, occurs only once every 18 years for a ...
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22 votes
3 answers
3k views

What is the accuracy of our knowledge about the planets orbits?

We have studied the solar system for a long time and have detailed 3 dimensional knowledge of all the various bodies in the solar system and how they move in space in relation to one another and also ...
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22 votes
3 answers
6k views

Gravity on a doughnut-shaped/Möbius planet

How different would the effects of gravity be if the planet we're on is in the shape of a torus (doughnut-shaped)? For an (approximately) spherical planet, it's slightly clear that objects would tend ...
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20 votes
5 answers
128k views

Why is Earth's gravity stronger at the poles?

Many sources state that the Earth's gravity is stronger at the poles than the equator for two reasons: The centrifugal "force" cancels out the gravitational force minimally, more so at the equator ...
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  • 507
20 votes
2 answers
11k views

Why Aren't Saturn's Rings Clumping into Moons?

While reading with my son about how a Mars-like planet collided with the early Earth that resulted in our current moon, it said the initial debris also formed a ring, but that ring ended up getting ...
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19 votes
1 answer
1k views

Could there be a body of water the size of a planet?

My friend and I were reading the news of the discovery of a black hole spewing huge amounts of water vapor into space, and it got us thinking: could there be a blob of liquid water in space the size ...
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18 votes
3 answers
4k views

If it was possible to dig a hole that went from one side of the Earth to the other...

...And you jumped in. What would happen when you got to the middle of the Earth? Would you gradually slow down, until you got to the middle and once you were in middle would every direction feel like ...
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18 votes
3 answers
1k views

Why don't more rocky planets/moons have appreciable atmospheres?

It seems obvious why mercury has no atmosphere, given its proximity to the sun--but yet Venus is also fairly close, and has an extremely dense atmosphere. Titan is a large moon with an atmosphere ...
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17 votes
2 answers
858 views

Was Leverrier-Adams prediction of Neptune a lucky coincidence?

According to historians both Adams and Leverrier used Bode's law to guess the distance to Neptune, which led to a vast overestimation of its orbital period (Adams - 227 years, Le Verrier - 218 years, ...
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16 votes
5 answers
4k views

What would happen if I were to fall into a massive hollow planet?

Imagine, if you will, there exists somewhere out there a supermassive planet. For some reason, this planet is only a shell of its former existence and all that is left is a crust of substantial size ...
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16 votes
2 answers
714 views

What is a "Trojan Moon"?

Today I read an article about Saturn's moon Helene, and it was described as a "Trojan Moon" but no further explanation was given. It was difficult to even get any context about the term from the ...
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16 votes
1 answer
7k views

Do all known planets and moons have magnetic field?

In this Wikipedia article it is stated, that magnetic field of Earth is caused by currents in her core. The same origin is for Jupiter magnetic field. For Moon (article) there is a magnetic field, ...
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16 votes
1 answer
498 views

Relationship between Mars and Earth rotation

Is it by pure random chance that Mars and the Earth have nearly the same day duration (Mars day is barely 40 minutes longer, which is just 3% difference), or there is some causal relationship between ...
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15 votes
2 answers
3k views

What would be the rate of acceleration from gravity in a hollow sphere?

Lets say the Earth is hollow and you are in the center of it (Same mass except all of it is on the outside like a beach ball) If you move slightly to one side now your distance is closer to that side ...
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15 votes
3 answers
3k views

Simulating solar system with Newton's law

I made a simulation in C++ with Newtons law and test it comparing the planets positions with the position from Solar system Calculator Don Cross (which I converted from JavaScript to C++) http://...
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15 votes
6 answers
4k views

What's the actual path of the planets?

I read about Kepler's Laws and in one of them he mentions that the path of a planet is an ellipse, with the sun as one of its foci (I'm narrowing down this to only our solar system). However though I'...
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15 votes
4 answers
3k views

Why is Uranus's axis of rotation tilted?

The poles of Uranus are 'in the wrong place', why is this? historically, do we have any evidence of its past? also, do we have an understanding of how its rotational axis might be evolving?
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15 votes
3 answers
380 views

How are newly discovered objects (stars, planets, galaxies...) named?

When a new astronomical object (star, planet, galaxy, comet, etc.) is discovered, what is the official procedure to name it? Who decides about the name of it? Can they be changed in time? Extra ...
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15 votes
2 answers
824 views

Is it possible to prove that planets should be approximately spherical using the calculus of variations?

Is it possible to use the Lagrangian formalism involving physical terms to answer the question of why all planets are approximately spherical? Let's assume that a planet is 'born' when lots of ...
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