One sunrise-to-sunrise day on Mercury lasts about two Mercury years.

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Mercury in true color
Space

176 days

One sunrise-to-sunrise day on Mercury lasts about two Mercury years.

On Mercury, the interval from one sunrise to the next averages about 176 Earth days: twice the length of its year. That surprising relationship comes from the way Mercury’s slow rotation combines with its rapid journey around the Sun, not from the planet standing still.

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Venus from Mariner 10
Space

243 days

A rotation on Venus takes longer than its entire year.

Venus takes about 243 Earth days to rotate relative to the stars, longer than its 225-day year. Its solar day, measured from one sunrise to the next, is shorter: about 117 Earth days.

Moving heart of the Crab Nebula
Space

1B tons

A teaspoon of neutron star would weigh about a billion tons.

A teaspoon-sized volume at neutron-star densities can have a mass of roughly a billion tons. This is a density comparison, not a suggestion that stable spoonfuls could be brought to Earth.

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