Astronomy Basics

Amazing Astronomy Facts

 
 
  • When you look at the Andromeda galaxy (which is 2.3 million light years away), the light you are seeing took 2.3 million years to reach you. Thus you are seeing the galaxy as it was 2.3 million years ago.
  • Light from the sun takes 8 minutes to reach you, thus you see the sun as it was 8 minutes ago. It might have blown up 4 minutes ago and you wouldn't know about it!
  • The Earth is not a sphere! It actually is an oblate spheroid, it is squashed slightly at the poles and bulges out at the equator due to its rotation.
  • Spare a thought for the constellations that never made it into the official list... these include Machina Electrica (the electricity generator), Officina Typographica (The Printing Office), and Turdus Solitarius (the solitary thrush)
  • When Galileo viewed Saturn for the first time through a telescope, he described the planet as having "ears". It was not until 1655 that Christian Huygens suggested the crazy theory that they might be an enormous set of rings around the planet.
  • If you could put Saturn in an enormous bathtub, it would float. The planet is less dense than water.
  • A teaspoon-full of Neutron star would weigh about 112 million tonnes.
  • Jupiter is heavier than all the other planets put together.
  • Even on the clearest night, the human eye can only see about 3,000 stars. There are an estimated 100,000,000,000 in our galaxy alone!
  • The tallest mountain in the solar system is Olympus Mons, on Mars at a height of about 15 miles, three times the height of Mount Everest. It covers an area about half the size of Spain.
  • If the sun were the size of a dot on an ordinary-sized letter 'i', then the nearest star would be 10 miles away.
  • Half-a-billionth of the energy released by the sun reaches the Earth
  • Temperatures on Venus are hot enough to melt lead.
  • If you could travel at the speed of light (186,000 miles per second) it would take 100,000 years to cross our galaxy!
  • Only one side of the moon ever faces Earth. The moons period of rotation is exactly the same as it's period of orbit.
  • Betelgeuse, the bright star on Orion's top-left shoulder, is so big that if it was placed where the sun is, it would swallow up Earth, Mars and Jupiter!
  • If you stand on the equator, you are spinning at about 1,000 mph in as the Earth turns, as well as charging along at 67,000 mph round the sun.
  • On the equator you are about 3% lighter than at the poles, due to the centrifugal* force of the Earth spinning.
  • The atmosphere on Earth is proportionately thinner than the skin on an apple.
  • On Mercury a day (the time it takes for it to spin round once) is 59 Earth-days. Its year (the time it takes to orbit the sun) is 88 days- that means there are fewer than 2 days in a year!
  • If a piece of the sun the size of a pinhead were to be placed on Earth, you could not safely stand within 90 miles of it!
  • Its estimated that the number of stars in the universe is greater than the number of grains of sand on all the beaches in the world! On a clear night, we can see the equivalent of a handful of sand.
  • Every year the sun evaporates 100,000 cubic miles of water from Earth (that weighs 400 trillion tonnes!)
  • Jupiter acts as a huge vacuum cleaner, attracting and absorbing comets and meteors. Some estimates say that without Jupiters gravitational influence the number of massive projectiles hitting Earth would be 10,000 times greater.
  • Astronomers believe that space is not a complete vacuum- there are three atoms per cubic metre.
  • Saturn is not the only planet with rings- Neptune has it's own ring system.

* Note: centrifugal force is not a "real" force, it is only a effect experienced by an object moving in a circular motion. See this page for more