How far is it to the first stars that formed in the universe?

"Are we there yet?" So goes one of the most common questions ever to be asked from the back seat during a long car ride. "Are we there yet?" "No," says the frustrated parent in the front seat.

Astronomers have a different answer. "Are we there yet?" "Almost," excited NASA scientists say. That is, we are almost at the point of viewing the first stars to form in the universe.

On March 9, scientists at the Space Telescope Science Institute in Baltimore, home of the Hubble telescope, unveiled the deepest image of the universe yet -- a mere pinpoint on the sky containing over 8,000 galaxies at a distance of over 13.2 billion light years away. The image is called the Hubble Ultra Deep Field, and it reveals the first galaxies to emerge about 500 million years after the Big Bang.

It took the magnifying power of Hubble to see such dim light, comparable to seeing a firefly on the moon -- one ten-billionth times fainter than what the human eye can detect. Scientists pointed Hubble at these galaxies for one million seconds to collect enough light to make a clear image.

The first stars formed just before the first galaxies, about 100 million years earlier. We can't quite see these objects yet. They formed about 13.5 billion years ago. These stars have all likely died, but we may be able to detect the light they emitted long ago with Hubble's successor, the James Webb Space Telescope, scheduled for launch in 2011. This light has been traveling through space for 13.5 billion years. Thus, we say these stars are located at a distance of 13.5 billion light years. (The Sun, in this regard, is 8 light-seconds away, because that's how long it takes for light to travel from the Sun to the Earth.)

Interestingly, a telescope called the Wilkinson Microwave Anisotropy Probe (WMAP) has "seen" an earlier period of the Universe, about 13.7 billion years ago. WMAP sees the afterglow of the Big Bang, called the cosmic microwave background. About a million years after the Big Bang, there was a period called the "dark ages" when there was no light -- that is, the Big Bang explosion was "over" and stars hadn't yet formed. So, WMAP allows us to see the universe as it was just before the dark ages, and the James Webb Space Telescope may allow us to see the universe as it emerged from the dark ages.

Piece by piece we are mapping the entire history of the universe. NASA's Beyond Einstein roadmap has an ambitious goal of studying the Big Bang itself, not just the afterglow from hundreds of thousands of years later. We may accomplish this feat later in the next decade. Then, at long last, we will have arrived.

This week's question is provided by Christopher Wanjek. Mr. Wanjek is a science writer supporting the Beyond Einstein initiative, a roadmap to understand the forces of nature beyond General Relativity and Quantum Mechanics through the study of the Universe from the Big Bang to black holes.