On April 18th, 2018, NASA’s Transitting Exoplanet Survey Satellite (TESS) took to space for the first time. By August, it began capturing the light curves of distant stars for signs of planetary transits, effectively picking up where the Kepler Space Telescope left off. Now, just a few months away from the end of its primary mission, NASA has put a year’s worth of images of the southern sky together to create the beautiful mosaic you see here.
This panoramic view of the southern sky is based on 208 TESS images, which were taken during the mission’s first year of science operations – which wrapped up this past July 18th. In that time, the spacecraft gathered data on many interesting events in the southern sky, as well as light curves that led to the discovery of 29 exoplanets so far with more than 1,000 candidate planets that are now being investigated.
The images it took also capture the beauty of the cosmic landscape it spent its first year observing. As Ethan Kruse, a NASA Postdoctoral Program Fellow who assembled the mosaic at NASA’s Goddard Space Flight Center, said in a recent NASA press release:
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“Analysis of TESS data focuses on individual stars and planets one at a time, but I wanted to step back and highlight everything at once, really emphasizing the spectacular view TESS gives us of the entire sky.”
Using its advanced suite of four wide-field cameras, each of which carry 16 charge-coupled devices (CCDs), TESS divided the southern sky into 13 sectors and observed each individually for a month. TESS’ cameras are able to capture a full sector of the sky in just 30 minutes, but ongoing observation is necessary to ensure that the spacecraft can detect any possible exoplanet transits.
Much like Kepler, TESS relies on Transit Photometry (aka. the Transit Method) to search for signs of exoplanets. This consists of observing stars for periodic dips in brightness, which are an indication of a planet passing in front of a star (aka. transiting) relative to the observer. This method is currently the most effective means of detecting exoplanets and also yields data on the planet’s orbital period and size.
During TESS’s first year of operations, each of its CCDs captured 15,347 images of the southern sky during 30-minute exposures of each sector. In total, TESS accumulated more than 20 terabytes worth of data, which is more than the entire contents of the US Library of Congress (which contains about 15 terabytes of data).
In addition to light curves that indicate (or suggest) the presence of exoplanets, TESS also managed to capture images of a comet that was traveling through our Solar System – which TESS imaged before officially commencing science operations. There’s also the distant supernovae it observed and a flare caused by a star that was being ripped apart by a Supermassive Black Hole (SMBH).
With its observations of the southern sky complete, TESS has since turned its attention to the Northern Hemisphere. This phase of its operations will wrap up in June of 2020; by which time, TESS will have completed the most comprehensive planet-hunting expedition to date.
Further Reading: NASA