That’s WMAP, Seen from Earth

Okay, now astronomers are just showing off. See the three little multicolored dots in the upper right of this image? That’s NASA’s WMAP satellite, seen from a distance of 1.5 million km. The photograph was taken from the 2.2 meter telescope at the European Southern Observatory at La Silla, Chile. Apart from demonstrating some impressive imagine power and technique, the astronomers are testing out new tracking techniques for ESA’s upcoming Gaia space observatory.

The technique for finding your place in the Universe is called astrometry. Star Trek’s Enterprise would rely on this kind of information to navigate from star to star. In reality, though, astronomers compile this information to understand the Solar System’s position in relation to the rest of the Milky Way.

The last mission focused on this process was ESA’s Hipparcos mission, which wrapped up in the year 1993. Hipparcos measured the distance to 120,000 stars with great accuracy, as well as another 400,000 stars with less accuracy.

ESA’s new mission, due for launch in 2011, is called Gaia, and will travel to the Sun-Earth L₂ Lagrangian point. From this vantage point, it’ll create a precise three-dimensional map of stars throughout the Milky Way galaxy, and beyond. All in all, it will eventually create a catalogue of 1 billion stars.

When Gaia finally launches, knowing its position accurately in the Solar System is everything. And so, astronomers on Earth will need to be able to track its position in the sky, and relay this data back to the spacecraft, so it can make its calculations.

By demonstrating that they can already track the WMAP spacecraft, currently at the L₂ Lagrangian point, the astronomers have proven that they should be able to watch Gaia as well. In fact, Gaia should be brighter than WMAP.

You might be wondering why the WMAP image shows three different colours. The astronomers photographed the region three times in black and white, and then artificially coloured them red, blue and green. Since the stars don’t move, the three colours add up to make them appear white. The moving WMAP is clearly different from the background.

Original Source: ESA Image of the Week