how big is our universehome-download pdf-print-friendly pdf-credits
image three pleides image

how far

- the sun
and planets


- across the
milky way



the distant

- how far
can we see
- how big is
the universe

parallax image
try this: jumping stars

These pictures were taken six months apart, when Earth was on opposite sides of its orbit. Can you tell which star is closer than the rest? Look for the star that appears to change postion, like your thumb when seen from two points of view.

+ click here to enlarge image


the stars

Traveling to the stars? Don’t pack for a week or a month. Pack for 70,000
years - the travel time to the nearest star beyond our Sun using our fastest spaceship!

As the Earth moves around the Sun, our view of nearby stars changes slightly against the background of other stars that are further away. Astronomers use this effect, called parallax, to determine the distance to the nearest stars.

1836. German scientist Friedrich Bessel, using a specially designed telescope, is the first to see a star’s position appear to change as the Earth moves around the Sun. He finds the star to be 700,000 times further away than our Sun!

ABOVE: The Pleiades star cluster is 400 light years away. One light year is 6 trillion miles. The blue veil is starlight reflecting off dust that envelops the cluster.