Escape Velocity

 

The table below gives the escape velocity from each object and from the Sun at the distance of that object's orbit.

Body Mass (kg) Radius (km) Orbit (AU) Escape Velocity (km/s)

from its surface

from the Sun at its orbit

Sun       1.99 x 1030 696000 0

618

N/A

Mercury 3.30 x 1023 2439 0.39

4.2

67
Venus 4.87 x 1024 6051 0.72

10.4

70
Earth 5.98 x 1024 6378 1.0

11.2

50
   Moon 7.35 x 1022 1738 (384000)

2.38

1.4 (from Earth)
Mars 6.42 x 1023 3393 1.5

5.0

34
   Phobos

1.08 x 1016

11

(9378)
11 m/s
3.0 (from Mars)
   Deimos 1.8 x 1015 6 (23459)
6.3 m/s
1.9 (from Mars)
Ceres 8.7 x 1020 467 2.8
0.50
25
Vesta 3.0 x 1020 265 2.3
0.39
28
Pallas 3.18 x 1020 261 2.8
0.40
25
Jupiter 1.90 x 1027 71492 5.2
59.5
19
   Io 8.93 x 1022 1815 (421000)
2.56
25 (from Jupiter)
   Europa 4.80 x 1022 1569 (671000)
2.02
19 (from Jupiter)
   Ganymede   1.48 x 1023 2631 (1070000)
2.74
15 (from Jupiter)
   Callisto 1.08 x 1023 2400 (1883000)
2.45
12 (from Jupiter)
Saturn 5.69 x 1026 60268 9.5
35.5
14
   Titan 1.35 x 1023 2575 (1221000)
2.64
7.9 (from Saturn)
Uranus 8.68 x 1025 25559 19
21.3
9.6
Neptune 1.02 x 1026 24764 30
23.4
7.7
Pluto 1.29 x 1022 1150 40
1.22
6.7
   Charon 1.90 x 1021 564 (19600)
0.67
0.3 (from Pluto)
Sirius B (a white dwarf star)   2 x 1030 11700 N/A

4775

50 (from 1 AU)
Black Hole (1 solar mass)  1.99 x 1030 6 N/A
c (speed of light)
50 (from 1 AU)

Note that the Gas Giant planets (Jupiter, Saturn, Uranus and Neptune) do not have solid surfaces. The radius of these planets is specified as the point where the pressure in their atmosphere is approximately equal to that at the surface of the Earth. Phobos and Deimos (the moons of Mars) are oddly shaped and the radius given is an average. Ceres, Pallas and Vesta are the three largest asteroids that orbit between Mars and Jupiter. In 1802 Ceres and Pallas were considered to be planets, but were downgraded to asteroids when it was realised there were many such things orbiting between Mars and Jupiter (see this US Naval Observatory page for more details).

Sirius B is our closest white dwarf star and is the unseen compaion to the white star Sirius, the brightest star in the night sky. A 1 solar mass black hole is quite small as there are some with millions of solar masses.

For comparison, here are the RMS speeds for certain gasses at STP:

Gas RMS (km/s)
H 1.97
He 1.39
H2 0.53
O2 0.49
CO2 0.42

 

Calculate it for yourself...

The escape velocity (v) of a body depends on the mass (M) and the radius (r) of the given body. The formula which relates these quantities is:

where G is called the Gravitational constant.

When calculating the escape velocity using this formula it is best to stick to the MKS system where the units for distance are meters, the units for mass are kilograms, and the units for time are seconds. In this system, the gravitational constant has the value:

G = 6.67 x 10-11 Newton-meter2/kilogram2.

 


Created by Grant Nicholson