Where does this come from, and can I check it?

Tidal friction lengthens the day by a couple of milliseconds a century. The figure is taken from NASA Science, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a space fact?

Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

The Moon is slowing Earth's spin

Tidal friction lengthens the day by a couple of milliseconds a century The Moon raises bulges in the oceans and the solid Earth, and Earth's rotation drags them ahead of the Moon. The bulge pulls the Moon forward in its orbit while Earth loses rotational energy. Leap seconds exist partly because the day keeps lengthening. It sits in Mondo's space collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NASA Science

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

Go further

World Geography trivia

More facts like this

The Moon is slowly drifting away from EarthLuni-solar tidal friction pushes the Moon outward by roughly four centimetres each year Tides come in pairs because of stretchingThe Moon pulls hardest on the near side, and the resulting imbalance bulges the far side too Spring tides have nothing to do with the seasonThe name comes from the old sense of springing upward, and the tides happen twice a month A day on Venus is longer than its yearVenus turns so slowly that its day outlasts its trip around the Sun Jupiter has the shortest day of any solar system planetThe gas giant completes a full rotation in under ten hours Uranus rotates almost entirely on its sideAn axial tilt of 98 degrees causes extreme seasons lasting over 20 years

Tags: tides, rotation, moon

The Moon is slowing Earth's spin: the short answers

Where does this come from, and can I check it?: Tidal friction lengthens the day by a couple of milliseconds a century. The figure is taken from NASA Science, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a space fact?: Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.