NASA continues to outdo itself with the magnificent images of space that it releases – but even by NASA’s high standards, a 12-year timelapse of the entire night sky is an impressive achievement.
The images were taken by the NEOWISE (Near-Earth Object Wide Field Infrared Survey Explorer) space telescope, which was launched in 2009 under the previous name ‘WISE’ to study the Universe beyond our Solar System.
Since then, it has been repurposed and renamed to track near-Earth objects such as asteroids and comets.
NEOWISE data provides scientists with invaluable insight into how celestial objects move and change over time (time-domain astronomy), whether it’s stars exploding or wandering across the night sky, or black holes gobbling up gas.
“If you go outside and look at the night sky, it might seem like nothing ever changes, but that’s not the case,” says astronomer Amy Mainzer, from the University of Arizona, which is the principal investigator for NEOWISE.
NEOWISE’s readings reveal the location of hundreds of millions of objects as well as the amount of infrared light each one emits. This data can then be analyzed to determine what an object is doing.
Every six months (the time it takes the telescope to travel half the way around the Sun), an entire sky’s worth of data is collected, and astronomers have now stitched together 18 of these maps to form the time lapse.
The maps have been particularly useful for studying brown dwarfs – objects that don’t quite have the mass to spark the fusion necessary to become a brightly-burning star, despite starting their existence in similar ways. Those that are closer to Earth appear to move faster across the sky than those that are further away, allowing NEOWISE to identify them more easily.
The telescope has now identified approximately 260 brown dwarfs, and we now know about twice as many Y-dwarfs – the coldest brown dwarfs of particular interest to astronomers, providing clues on the efficiency of star formation and its timing in the evolution of our galaxy.
“We never anticipated that the spacecraft would be operating this long, and I don’t think we could have anticipated the science we’d be able to do with this much data,” says astronomer Peter Eisenhardt, from the NASA Jet Propulsion Laboratory in California.
Through the telescope’s sky scanning, we’re also learning more about how stars form: protostars stand out as flickering objects before becoming stars, and scientists are now tracking nearly 1,000 of them to see how they develop.
Then there’s the black hole, which is perhaps the most intriguing celestial object of all. NEOWISE data can be used to identify bursts of infrared light emitted by clouds of matter churning around black holes, allowing us to see these objects from a greater distance.
The work is far from finished, and NEOWISE’s mapping journey continues, with two more sky maps due in March 2023. Expect the project to reveal a lot more – activity that you can’t see when looking up at the stars at night.
“Stars are flaring and exploding,” says Mainzer. “Asteroids are whizzing by. Black holes are tearing stars apart. The Universe is a really busy, active place.”
You can learn more at the NEOWISE Project website.
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