Astronomy

The James Webb Space Telescope has found mature galaxies only a few hundred million years after the Big Bang. Such objects appear earlier than standard cosmology expected, so astronomers are rechecking how fast galaxies could grow in the young universe.

The Moon drifts 3.8 cm farther from Earth every year, about the rate fingernails grow. Two hundred million years ago, in the dinosaur era, the Moon was closer and Earth's spin faster: a day lasted about 23 hours. Apollo 11 retroreflectors let lasers measure the retreat.

Helium was discovered on the Sun before on Earth. During an 1868 eclipse, astronomers found an unknown yellow line in the solar Spectrum; Norman Lockyer named the new element after Helios. It was not isolated on Earth until 1895.

Earth's closest planet on average isn't Venus but Mercury. Bigger orbits spend longer on the far side of the Sun, so average distance grows. Mercury's tiny orbit keeps it near every planet. Earth–Mercury averages 1.04 AU, Earth–Venus 1.14 AU. The "Whirly Dirly Corollary."

The Moon's orbit doesn't spiral around Earth as most people imagine. Because the Earth-Moon distance is tiny compared to the Earth-Sun distance, the Moon's actual path through space is nearly circular, traveling alongside Earth around the Sun.

Earth has 365 days in a year, but actually rotates 366 times. The extra rotation comes from its orbit around the Sun — an example of the coin rotation paradox.