The Hubble Deep Field
Click on image for full size
NASA
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. Light moves at the speed of 300,000,000 meters/second (186,000 Miles/second). At short distances the light travel time is only a fraction of a second. However, the Sun is so distant from Earth (150,000,000 Kilometers) 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 (when Humans first began walking the Earth).
The Hubble Space Telescope has taken a picture called the Hubble Deep Field (pictured here). When we gaze at its ancient galaxies we are seeing a distant part of the universe as it was billions of years ago (when Earth was still in its infancy).
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:
There is a radiation that fills the universe, called Cosmic Microwave Background Radiation (CMB). CMB radiation is the heat left over from the time after the Big Bang, when the universe was really hot!
...moreSome of the best news of the week is that the Microwave Anisotropy Probe (MAP) was launched successfully last Saturday! Liftoff on its Delta II rocket occurred on time on June 30, 2001. The MAP teams says
...more
In the 1960's, the United States launched some satellites to look for very high energy light, called Gamma Rays. Gamma Rays are produced whenever a nuclear bomb explodes. The satellites found many bursts
...more
During the early 1900's, which is not very long ago, astronomers were unaware that there were other galaxies outside our own Milky Way Galaxy. When they saw a small fuzzy patch in the sky through their
...more
Neutron Stars are the end point of a massive star's life. When a really massive star runs out of nuclear fuel in its core the core begins to collapse under gravity. When the core collapses the entire star
...more
Spiral galaxies may remind you of a pinwheel. They are rotating disks of mostly hydrogen gas, dust and stars. Through a telescope or binoculars, the bright nucleus of the galaxy may be visible but the
...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 core it begins to bloat into a red giant. This will happen to our sun in 5 Billion years.
...more
