Celestial body that orbits following an elliptical path around a star or stellar remnant.
42
votes
5answers
2k views
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 ...
19
votes
6answers
2k 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)?
19
votes
1answer
659 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 ...
18
votes
4answers
1k 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?
18
votes
3answers
592 views
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.
...
15
votes
2answers
111 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 ...
15
votes
3answers
402 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?
14
votes
5answers
1k views
Why does the moon face earth with the same side?
I know this is an astronomy question, but no such stackexchange site exists. So here I am, asking about the physics of the solar system.
I know that the rotation period of the moon equals its ...
14
votes
2answers
272 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 ...
14
votes
1answer
232 views
Why don't any of the gas giants have moons of Earth's mass (or greater) that orbit them? Is this generalizable to exoplanet gas giants?
Now, we know that the composition of the outer planets tend to contain a much higher ratio of ice over rock. [1] So the lack of Earth-like moons around the outer planets that this could be an artifact ...
13
votes
9answers
3k views
Why are orbits elliptical?
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 ...
13
votes
1answer
3k 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 ...
13
votes
2answers
847 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 ...
13
votes
3answers
209 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 ...
13
votes
3answers
111 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 ...
12
votes
7answers
653 views
What is the current status of Pluto?
Pluto has been designated a planet in our solar system for years (ever since it was discovered in the last century), but a couple of years ago it was demoted.
What caused this decision? And is there ...
11
votes
1answer
138 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 ...
10
votes
3answers
445 views
Can you damage your eyes viewing Venus?
Whilst I know it is extremely dangerous to view the sun using a telescope (or even just looking directly at it for prolong periods) can you do permanent damage to your eyes looking at Venus through a ...
10
votes
2answers
380 views
Is it possible to see satellites with the naked eye?
Every now and then I notice some very bright "stars" in the sky. They tend to be very few (one or two, usually), and are quite much brighter than any other star out there. Often they're perfectly ...
10
votes
2answers
175 views
How large can planets or moons appear?
In many artistic impressions or movies there are pictures or scenes where the sky is filled with an enormous moon (as seen from a planet) or vice versa.
I wonder if there is an upper limit to the ...
10
votes
1answer
212 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 ...
10
votes
1answer
130 views
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 ...
9
votes
2answers
62 views
What are the prerequisites for considering any other planet to be habitable?
Well, there is a measure of how a planet could be considered like Earth, called Planetary habitability. Based on this measure, what are the prerequisites needed to consider a planet to be a habitable ...
9
votes
4answers
225 views
Two planets in same orbit - not planets?
Let us pretend for a moment that there are two identical planets that are exactly opposite their star from each other and are the same distance from said star. (This would make them, at all times, ...
8
votes
4answers
3k views
Are there planets that do not rotate on their axis?
I was reading a thread about how a pendulum would be affected if the Earth did not rotate and Larian's answer made me wonder if all planets rotate necessarily due to physics.
So that's the question: ...
8
votes
3answers
180 views
Are planetary orbits measured from the Sun's surface or centre?
I would imagine planetary orbits are measured from the Sun's centre and not its surface. Is that true?
I can't find anywhere that actually states this.
8
votes
1answer
506 views
How big (compared to our moon) would Saturn look from Titan's surface?
How large in the night sky would Saturn look from Titan's surface? I believe they are tidally locked.
8
votes
3answers
309 views
Is it possible that 5 planets can revolve around a single star in a single orbit?
I'm writing a novel and I'm quite confused if this system could be possible in the real universe. Is it possible that a system exist, where 5 identical planets which could be of same characteristics ...
8
votes
1answer
14 views
Ring height stats?
I'm working on a basic simulation system which will include planets with rings, I want to create dust and asteroids within a 3D ring but I'm struggling to find any stats on the sort of height ranges a ...
8
votes
1answer
75 views
Biggest crater in the Solar System
It seems that the biggest crater in the Solar System is Borealis Basin on Mars. The Wikipedia entry and this piece of news say it has been formed by an impact with a body of around 1600 - ...
8
votes
1answer
90 views
Are Uranus and Neptune too big for their location?
So I was watching some TV, and I heard Dr. Plait mention that the planets Uranus and Neptune are too big to be located so far out in our solar system. Now, I heard his explanation on the show as to ...
8
votes
3answers
1k views
What would happen if the polar ice caps of Mars melted?
My dad told me that Mars' polar ice caps are made of H2O and CO2. If they melt, would it add an atmosphere to Mars and allow life?
8
votes
1answer
460 views
For observing planets what kind of telescope offers the best view?
I've heard that using a refractor is better than a reflector when it comes to planets to best reproduce their colors. But perhaps other factors can weight in too? For example, do you want a slow or ...
7
votes
1answer
312 views
Falling into Saturn or Jupiter, would we pass through it until we hit the nucleus?
If we fall into Saturn or Jupiter, would we pass through it until we hit the nucleus?
Or would we hit the surface and stop there?
7
votes
3answers
226 views
How do you explain Kepler's third law in general terms without complex math?
I understand the first law-elliptical orbits, and the second-equal area in same time, but I need help with the third one. Note that I am not in an AP course or taking calculus at the moment so simple ...
7
votes
4answers
432 views
Are “broken” planets possible in the real world?
In the Star Wars universe, there are mentioned (or rather shown) two planets that had some kind of great explosion in their history. First is Peragus, with its exposed core, that partially exploded ...
7
votes
1answer
49 views
How plausible is a subsurface ocean on Pluto?
According to this article on physorg.com, it's likely that Pluto has a subsurface ocean of liquid water. It suggests that the ocean would be about 165 km deep, under an equally deep crust of solid ...
7
votes
3answers
43 views
Is a rogue 'exoplanet' classed as a exoplanet?
Given that the term planet strictly (according to the IAU) refers to a body around the sun, rogue planets can't be called that, so I assume they must be called rogue exoplanets?
But do they even ...
6
votes
1answer
38 views
Transit of Mercury: how did he see it?
On November 7, 1631 Pierre Gassendi saw the transit of Mercury across the face of the Sun. How did he see it? I mean what instrument was used to reduce the apparent brightness of the Sun?
6
votes
3answers
1k views
What is the irregularity in Uranus' orbit that is caused by Neptune?
I carefully read the Wikipedia article Discovery of Neptune, and I don't get what the irregularity of Uranus orbit was that lead to the discovery of Neptune. Years ago, I watched some educational film ...
6
votes
1answer
56 views
Is it possible to determine astronomically/astrophysically whether other planets have ever encountered polarity reversal?
We know of geomagnetic flip in Earth's history by studying geologic data. Given other planets in the system also possess a magnetic field leads to the assumption that such polarity reversal may not be ...
6
votes
1answer
78 views
Will Neptune change Pluto's orbit some day?
My seven-year-old son loves astronomy-- so much so that we read space books before bed time. One of our books talks about Pluto's orbit crossing over Neptune's orbit and will be (or is) closer to the ...
6
votes
1answer
35 views
Are there Trojan family or Hilda family satellites locked in Earth's orbit?
Jupiter has many Trojan asteroids located at Lagrangian points L4 and L5 and Hilda asteroids dispersed between points L3, L4, and L5.
Does the Earth have similar satellites? If so, how many?
6
votes
1answer
292 views
How many Pluto sized planetoids have been discovered?
How many planetoids have been discovered that are, say, 50% the size of Pluto or larger? Where are they?
Incidentally, what is the difference between a planet, a planetoid, and an asteroid?
6
votes
3answers
171 views
Falling through the rotating Earth
Suppose you were standing on the rotating Earth (not necessarily Equator or the poles) and suddenly your body lost the ability to avoid effortlessly passing through solid rock.
Because the earth's ...
6
votes
1answer
21 views
Liquid Water in “mid-ice” on Europa. Mechanism?
Recently I read this entry by Dr. Phil Plait (a.k.a. The Bad Astronomer). He is talking about a lake of water contained within the ice layer of Europa.
the lake is completely embedded in the ice ...
6
votes
1answer
258 views
Why does Jupiter emit more energy than it receives?
I hear that Jupiter and Saturn emit more energy than they receive from the Sun.
This excess energy is supposedly due to contraction.
Is this accepted as fact (or is it controversial)?
Does this ...
6
votes
1answer
134 views
Frequency of nomad planets passing within 30 AU of the sun
A recent estimate by the Kavli Institute for
Particle Astrophysics and Cosmology (a joint
institute of Stanford and SLAC) is that there
are circa 100000 times as many 'nomad planets' as stars
I ...
6
votes
1answer
75 views
Axial Tilt and precession rate of exoplanets
The Earth's axis is 23.5 degrees away from othogonality to the ecliptic, and it takes about 26 000 years for it to precess fully. I have neither an intuitive sense nor the formula for precession ...
6
votes
0answers
84 views
How scientists could say that such meteorite comes from Mars
How could scientists affirm that a meteorite comes from Mars and not from another source ?
This is a probability or an absolute certainty ? How much percent ?
