# Tag Info

5

Gravitational waves Presumably, there would be gravitational waves emitted as the two compact objects slowly came close to merging. Given their small cross-sections, a direct, head-on collision is highly unlikely. A more plausible scenario involves an interaction with a third massive body.$^{\dagger}$ The white dwarf and neutron star would be inserted into ...

3

Cox & Loeb 2008 performed one of the few simulations of the Milky Way/Andromeda collision of which I'm aware. It's not particularly easy to simulate a galactic merger, so the lack of detailed numerical treatments shouldn't be that surprising. Nevertheless, they were able to determine certain properties of the remnant, which they showed would appear to be ...

0

Viewed from earth? At night it would look black with some white dots and a moon, during the day it would look blue with the sun.

1

I did see this answered on: https://www.quora.com/How-do-you-calculate-the-apparent-magnitude-brightness-of-planets-from-within-the-same-solar-system So i have copied/pasted the answer below. This is not my answer, i am copying/pasting it as it seems an appropriate answer. All credit goes to Milan Minic. Calculations of the apparent magnitudes m start with ...

1

Another possibility is a world in a multiple star system. The planet might be tidally locked to its primary, but would also be warmer when another star approaches, and cooler if the other star moves behind the primary. For instance, in Brian Aldiss's book Helliconia, the planet of the same name orbits a sun-like G-class star called Batalix, which itself ...

2

Both the other answers (at this time) suggests making the orbit eccentric. The variable distance from the sun makes the planet hot or cold. This is correct. But there is one important aspect of this situation neither answer mention. If you have a tidally locked planet in an eccentric orbit, the tidal lock isn't perfect. There is an east-west "wobble". ...

0

There's no reason that a moon revolving around a planet has to take longer than a day. Jupiter's day lasts around 10 hours. Its fastest moon, Metis, revolves around the planet about every 7 hours. Changing the distance and speed of the moon could have other effects on the planet, such as changing tides and possibly altering the orbit (like how Charon pulls ...

1

Yes. Yes, technically. You can accurately keep time with the moon, although 'accurate' here doesn't mean much because you're talking about on a scale of either hours (using the moon's passage across the sky) or months (measuring by moon cycles). Both of these are consistent enough so you don't need to worry about fluctuations. Having a moon revolve around ...

17

Yes, if the orbit isn't circular. Seasons can definitely occur on a tidally locked planet. Just like normal planets, tidally-locked planets don't need to have perfectly circular orbits. This means that over the course of a single orbit, this planet would receive different amounts of light from the star as it slowly moves away and then towards it. This will ...

4

Depends on the orbit I'm drawing on my answer to a different question here. Let's start with an overview of why there are seasons. I really like this description: We have seasons because the earth is tilted (wonky) as it makes its yearly journey around the sun. The Earth's axis is tilted at an angle of 23.5 degrees. This means that the Earth is ...

1

Unlikely - but Yes So taking this question to be "Could a planet rotate around an axis in the elliptic and tangential to its orbit?" The answer is: "Sure - but it takes very specific setup." So the planets all rotate because the swirling cloud of gas that they formed from rotated. Momentum is conserved, and there is nothing that opposes this motion. ...

2

Yes, for a given definition of 'North Pole'. You see, there are three different 'North Pole's Geographic North Pole, which is defined as 'the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface' (ignoring precession). Magnetic North Pole, defined as 'the point on the surface of Earth's Northern Hemisphere at which the ...

10

I'm going to assume that the question you're asking is 'Can the Earth additionally rotate up-and-down?', because, Matthew's answer has pointed out, we define 'up and down' based on the planet's already spinning axis. The only way this question makes sense is that you're asking whether the Earth can additionally spin up-and-down. And the answer to that is a ...

4

As you say, Uranus does. All it would mean is that the axial tilt would be 90 degrees. This is unlikely in the course of normal planetary formation, so (as with Uranus) it would probably take a series of impacts early in the planet's history to point its axis in the appropriate location. Now, if we're talking about Earth, things would obviously look a lot ...

20

No. The way we define latitude and longitude is based on the planet's axis of rotation. You can certainly (AFAIK) have a planet with a 90° axial inclination, or (probably) a planet that is identical to Earth except with all the land masses rotated 90°, but unless you completely change the definition of "pole", the poles will, by definition, be stationary w.r....

2

Your migration model falls in line with what is called a hot Jupiter. One possibility is that a Jupiter/Saturn like planet migrated inward disturbing the orbits of planets which had already formed. Over time two of these planets ended up getting captured by the hot Jupiter, becoming moons. Captured moons are not uncommon (see Neptune's moon Triton). Also, ...

Top 50 recent answers are included