Question

How big is the moon Titan compared to the Earth? How is the gravity different between these two planetary bodies?

Answer 1

Around half of Earth's radius is the radius of Titan. The surface gravity of Titan is `"1.353 m"//"s"^2`, meaning that the gravity on Titan is about 7.3 times weaker than on Earth.

Explanation:

Size:

The radius of Earth is:
`"6,371 km"` or `"6,371" * 10^3 "m" = "6,371,000 m"`

Whereas the radius of Titan is:
`"2,575.5 km"` or `"2,575.5" * 10^3 "m" = "2,575,500 m"`

Then

Difference in Size `= "Titan's Radius"/"Earth's Radius"`

`"2,575,500"/"6,371,000" = 0.404 ~= 0.5`

Meaning about half the size of Earth's radius.

Here is a comparison of the size of Titan (in the middle) compared to that of Earth and the Moon.

(from en.wikipedia.org)

Gravity:

The surface gravity on Earth is `9.807 "m/s"^2` and the surface gravity on Titan is `1.353 "m"//"s"^2`

So the difference between these two gravitational bodies is around:

Difference in Gravity `="Earth's Gravity"/"Titan's Gravity"`

`9.807/1.353 = 7.248 ~= 7.3`

Meaning that the gravity on Titan is about 7.3 times weaker than on Earth.