When a gigantic star dies and blows up, the astronomers call it a "supernova." Over the past 100 years, astronomers have observed thousands of these explosions.

However, they were seeing the star after the explosion took place. They were seeing the hot debris from the explosion racing outward. It would be like seeing fireworks a few seconds after they go off, when the colorful lights are shooting away from the puff of smoke that mark the locations of the actual explosion.

But now the NASA’s NASA’s Swift satellite has caught the images of a star that actually blow up.

On January 9, 2008, Alicia Soderberg and Edo Berger of Princeton University, in Princeton, N.J., were using Swift’s X-ray Telescope to observe a distant spiral-shaped galaxy known as NGC 2770. At 9:33 in the morning Eastern Time, the telescope picked up a powerful burst of X-rays coming from the galaxy. The event lasted 5 minutes. The newly born supernova is now known as SN 2008D.

Alicia Soderberg said they were lucky to observe the right place for the right time. Together with Berger, she organized a plan to use telescopes in space and on Earth to follow-up Swift’s discovery.

In the next few weeks, the observations made with NASA’s Hubble Space Telescope and Chandra X-ray Observatory confirmed that Alicia Soderberg and Edo Berger indeed have witnessed the actual explosion of a giant star in real time.

The X-rays were due to a powerful blast wave bursting through the star’s outer layers, and blowing it to “Kingdom Come.” The blast wave itself was triggered deep inside the star, when the nuclear engine at the center ran out of fuel and collapsed.

This is the first time when the astronomers have actually observed such a phenomenon and it was a perfect occasion to confirm their theories.

The observations also show that SN 2008D is an ordinary Type Ibc supernova, which occurs when a massive, compact star explodes. Significantly, radio and X-ray observations found no evidence that a jet played a role in the explosion, ruling out a rare type of stellar explosion known as a gamma-ray burst.

A typical supernova occurs when the core of a massive star runs out of nuclear fuel and collapses under its own gravity to form an ultradense object known as a neutron star. The newborn neutron star compresses and then rebounds, triggering a shock wave that plows through the star's gaseous outer layers and blows the star to smithereens. Astronomers thought for nearly four decades that this shock "break-out" would produce bright X-ray emission lasting a few minutes.

But until this discovery, astronomers have never observed this signal. Instead, they have observed supernovae brightening days or weeks later, when the expanding shell of debris is energized by the decay of radioactive elements forged in the explosion.

"Seeing the shock break-out in X-rays can give a direct view of the exploding star in the last minutes of its life and also provide a signpost to which astronomers can quickly point their telescopes to watch the explosion unfold," says Edo Berger, a Carnegie-Princeton Fellow at Princeton University.