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We use telescopes to
collect lots of light and
focus it onto detectors
using mirrors or lenses.
Large modern telescopes,
like the Keck Telescope
shown below, can collect
6,000,000 times as much
light as the human eye.
Keck Telescope
Your weight is different on other planets because the gravity is different. You have not changed of course, so your mass is always the same.
We calculate weight by multiplying mass by the gravity on the surface of the planet.
So, if you know your weight on Earth and the surface gravity on Earth, you can calculate your mass. You can then calculate your weight on any other planet by using the surface gravity of that planet in the same equation.
You can work it out for yourself using the surface gravity values in the following planetary data sheet. You can then check your answers using the weight calculator.
| Facts and Figures | Mercury | Venus | Earth | Mars | Jupiter | Saturn | Uranus | Neptune |
| Orbital Distance (AU)1 | 0.38 | 0.72 | 1.0 | 1.52 | 5.2 | 9.45 | 19.2 | 30.06 |
| Radius (KM) | 2,440 | 6,052 | 6,378 | 3,397 | 71,492 | 60,268 | 25,559 | 24,746 |
| Mass (Earth Masses)2 | 0.055 | 0.82 | 1.0 | 0.11 | 318 | 95.2 | 14.5 | 17.1 |
| Year Length (Earth Days) | 88 | 225 | 365.25 | 687 | 11.9 Years |
29.45 Years | 84.0 Years | 164.8 Years |
| Day Length (Earth Days) | 176 | 117 | 1.0 | 1.03 | 0.41 | 0.43 | 0.75 | 0.67 |
| Surface Gravity (g)3 | 0.38 | 0.91 | 1.0 | 0.38 | 2.34 | 0.93 | 0.92 | 1.12 |
| Surface Temperature | -200 to 400 °C | 460 °C | -80 to 50 °C | -150 to 20 °C | -110 °C | -140 °C | -190 °C | -200 °C |
| Number of moons | 0 | 0 | 1 | 2 | 63 | 60 | 27 | 13 |
