Difference between revisions of "Talk:681: Gravity Wells"

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(table of gravity well depths)
(my 2 cents)
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: Randall wasn't kidding about the Sun being "very very far down"; its well is 100 times deeper than Jupiter's!
 
: Randall wasn't kidding about the Sun being "very very far down"; its well is 100 times deeper than Jupiter's!
 
:[[User:Wwoods|Wwoods]] ([[User talk:Wwoods|talk]]) 19:47, 12 April 2013 (UTC)
 
:[[User:Wwoods|Wwoods]] ([[User talk:Wwoods|talk]]) 19:47, 12 April 2013 (UTC)
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:: OTOH, from the table above i'm thinking that the 5.4 might be the Venus figure, and it was wrongly placed besides Earth...
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:: Secondly, what i found interesting was that the Earth's 6.4 looks so much like its radius! I wonder if it's merely a coincidence, or there's a connection between the two... -- [[Special:Contributions/141.101.99.233|141.101.99.233]] 21:25, 30 October 2013 (UTC)

Revision as of 21:25, 30 October 2013

Why is Earth's well's depth listed as 5478km but as 6379km in the inset? Compare with Mars which has 1286 in both places. 87.174.225.131 07:21, 12 April 2013 (UTC)

Best guess is either a goof, or that the lower number is just for Earth itself, while the greater number is for the Earth/Moon system as a whole. Proportionally speaking, we have the largest moon in the solar system, so maybe it wouldn't nicely fit in the Earth well as easily as Mars's and Jupiter's moons do.--Druid816 (talk) 08:28, 12 April 2013 (UTC)
It may be the height needed to go from one gravity well to another. You don't have to get all the way up to escape speed for that.


Adapted from the table in Escape velocity, using h = V_e^2 / 2g:
Location with respect to Ve (km/s) Well depth (km) Location with respect to Ve (km/s) Solar well (Mm) Total depth (Mm)
on the Sun, the Sun's gravity: 617.5 19,435,000 19,435
on Mercury, Mercury's gravity: 4.3 942 at Mercury, the Sun's gravity: 67.7 233.6 235
on Venus, Venus' gravity: 10.3 5,407 at Venus, the Sun's gravity: 49.5 124.9 130
on Earth, the Earth's gravity: 11.2 6,393 at the Earth/Moon, the Sun's gravity: 42.1 90.3 97
on the Moon, the Moon's gravity: 2.4 294 at the Moon, the Earth's gravity: 1.4 91
on Mars, Mars' gravity: 5 1,274 at Mars, the Sun's gravity: 34.1 59.3 61
on Jupiter, Jupiter's gravity: 59.5 180,400 at Jupiter, the Sun's gravity: 18.5 17.4 198
on Ganymede, Ganymede's gravity: 2.7 372
on Saturn, Saturn's gravity: 35.6 64,600 at Saturn, the Sun's gravity: 13.6 9.43 74
on Uranus, Uranus' gravity: 21.2 22,907 at Uranus, the Sun's gravity: 9.6 4.7 28
on Neptune, Neptune's gravity: 23.6 28,400 at Neptune, the Sun's gravity: 7.7 3.02 31
on Pluto, Pluto's gravity: 1.2 73
at Solar System
galactic radius,
the Milky Way's gravity: 525 14,000
Randall wasn't kidding about the Sun being "very very far down"; its well is 100 times deeper than Jupiter's!
Wwoods (talk) 19:47, 12 April 2013 (UTC)
OTOH, from the table above i'm thinking that the 5.4 might be the Venus figure, and it was wrongly placed besides Earth...
Secondly, what i found interesting was that the Earth's 6.4 looks so much like its radius! I wonder if it's merely a coincidence, or there's a connection between the two... -- 141.101.99.233 21:25, 30 October 2013 (UTC)