The University of Texas at Arlington

The University of Texas at Arlington

UTA Planetarium

UTA Planetarium

Ask the Astronomer Q&A

Tag: "eclipse"

  • General relativity proved that light can bend based on a lot of gravity being forced onto the light. What are the two proofs of this?
  • The fact that light is bent by gravity was predicted by Einstein's General Theory of Relativity. The first observational evidence was given by Eddington and his team, who measured the effect during a solar eclipse in 1919. The measured value was very close to the one predicted by Einstein's theory.

    (Tags:  albert einstein  eclipse  gravity  light  theory of general relativity)
  • Since it takes the moon about 28 days to orbit the earth, does that mean a solar eclipse happens somewhere every 28 days?
  • If the moon orbited in the same plane as the ecliptic – Earth’s orbital plane – we would have two eclipses every month. There’d be an eclipse of the moon at every full moon. And, two weeks later, there’d be an eclipse of the sun at new moon for a total of at least 24 eclipses every year. But the moon’s orbit is not the same as the ecliptic. It is inclined to Earth’s orbit by about 5 degrees. Twice a month the moon intersects the ecliptic at points called nodes. If the full moon or new moon is appreciably close to one of these nodes, then an eclipse is not only possible – but inevitable. Even though the moon’s orbit is inclined to that of Earth – and even though there’s not an eclipse with every full and new moon – there are more eclipses than you might think. There are from four to seven eclipses every year. Some are lunar, some are solar, some are total, and some are partial.

    (Tags:  earth  eclipse  moon  sun)