Speed of light
Light can travel around the earth 7.5 times in 1 second.
186,282 miles per second
5,878,612,843,200 miles per year (1 light year)
Size Comparison (distances not to scale)
Diameter of sun: 865,000 miles
Diameter of earth: 7,917 miles
(Distance from earth to sun:92,960,000 miles.)
Our Galaxy (The "Milky Way")
Closest star to our sun: Alpha Centauri
Distance: 4.37 light years (25 trillion miles)
The Milky Way
Diameter: 180,000 light years
Number of stars: at least 200 billion
Number of planets: at least 100 billion
Andromeda Galaxy (Our nearest galaxy)
Distance: 2.5 million light years
Diameter: 220,000 light years
Number of stars: 1 trillion
The Hubble space telescope took a time exposure of a small area of the sky.
The area was the size of the square.
The Hubble eXtreme Deep Field (XDF) time exposure found 5,500 galaxies.
Number of galaxies in the observable universe: 176,000,000,000
History of the Universe Compressed to One Year
Eusthenopteron foordi Whiteaves (lobe fish) lived 385 million years ago.
Oldest known fossil of an arm, hand, and fingers.
Fish > tetropods > humans..
Sahelanthropus tchadensis lived 7 to 6 million years ago.
One of the oldest known species in the human family tree.
Homo habilis lived 2.4 million to 1.4 million years ago.
One of the earliest members of the genus Homo.
Homo erectus lived 1.89 million to 143,000 years ago.
Oldest known early humans to have possessed modern human-like body.
Homo neanderthalensis (Neanderthal) lived 400,000 to 40,000 years ago.
Our closest extinct human relative.
Tibetan "sky burial."
Excavated ground burial.