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Eclipse of the Moon – Space science

By |2019-05-23T21:28:46-07:00August 18th, 2017|Physics|

An eclipse of the moon. You can see the curved shadow of the Earth. What is an eclipse of the moon? An eclipse of the moon happens when the Earth gets between the sun and the moon, so the light from the sun can't get to the moon to be reflected towards the Earth. In other words, the shadow [...]

How old is the Earth? – Astronomy

By |2019-05-22T11:28:46-07:00August 18th, 2017|Physics|

Earth from space: How old is the Earth? When did the Earth form? Like Mercury and Venus and the other planets that go around the Sun, the Earth probably formed a little more than four and a half billion years ago. (That's about 4,600,000,000 years ago.) What's the sun made of? How do planets form? All our physics articles What [...]

What does circa mean? Measuring time

By |2019-04-05T13:04:29-07:00May 30th, 2017|History|

A mosaic showing a circus from the 500s AD in Gafsa (North Africa), now in the Bardo Museum Can you see the people sitting in the stands? The central posts to turn around? The charioteers whipping the horses? What does ca. stand for? Ca. is short for the Latin word 'circa', which means [...]