Tools

Interactive astronomy tools

Learn by experimenting. Each tool explains what it calculates and where the numbers come from.

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  Planet weight

  See how much you would weigh on other planets and why gravity changes your reading.

  Open tool
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  Planet age

  Convert your Earth age to years on Mars, Jupiter, and every other planet.

  Open tool
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  Compare planets

  Compare size, gravity, mass, temperature, and more side by side.

  Open tool

• Tonight's sky

  Which planets and Moon phase are visible from your location tonight.

  Open tool