The Hubble Deep Field
Click on image for full size
Looking Back in Time
When you look out into space you are actually looking back in time. This is because of the speed of light. At short distances the light travel time is less than a second. But, the Sun is so far from Earth that its light takes 8 minutes to reach us. So when you look at the sun in the sky (never look at it directly, you'll go blind) you see it as it was 8 minutes ago.
As distances get larger so does this "look-back time." The closest star, Alpha Centauri, is so far away that its light takes 4.3 years to reach us. When we look at the closest spiral galaxy to our own Milky Way, the Andromeda galaxy, we see it as it was 2 million years ago. That's when Humans first began walking the Earth.
The Hubble Space Telescope has taken a picture called the Hubble Deep Field (pictured here). When you look at these galaxies we are seeing a distant part of the universe as it was billions of years ago. That's when Earth was just beginning to form.
Shop Windows to the Universe Science Store!
The Summer 2010 issue of The Earth Scientist
, available in our online store
, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.
You might also be interested in:
Satellites in the 1960's looked for a type of light called Gamma Rays. They found bursts of Gamma Rays coming from outer space! They can't hurt you. They are stopped by the Earth's atmosphere. We have...more
When we look up at the night sky, we notice that there are many stars in our sky. Stars must like to live together in star cities - galaxies. Our city of stars is called the Milky Way, and it is home to...more
Neutron Stars form when really big stars die. When such a star runs out of fuel its center begins to collapse under gravity. When the center collapses the entire star collapses. The surface of the star...more
Spiral galaxies may remind you of a pinwheel that blows in the breeze. Like a pinwheel, a spiral galaxy is rotating, and it has spiral arms. Through a telescope or binoculars,a spiral galaxy may look...more
When stars like our own sun die they will become White Dwarfs. As a star like our sun is running out of fuel in its center it grows into a red giant. This will happen to our sun in 5 Billion years. The...more
What's in a Name: Arabic for "head of the demon" Claim to Fame: Represents Medusa's eye in Perseus. A special variable star that "winks" every 3 days. Type of Star: Blue-white Main Sequence Star, and...more
What's in a Name: Nicknamed the "Pup" because it is the companion to Sirius, "the Dog Star" Claim to Fame: Highly compressed white dwarf remnant. Density about 50,000 times that of water. It has approximately...more