TESS Discovers 329 Exoplanets: How NASA’s Telescope Revolutionizes Astronomy

NASA telescope illustration (slashgear)

Timlo.net—One of the largest research areas in astronomy today is the discovery of exoplanets, that is, planets outside our solar system. With over 5,000 known exoplanets and more being discovered every month, you might think the field is well established – but in truth, this area of ​​research is fairly new, with exoplanet research only really starting to develop in the last decade or so. A major factor in the growing popularity of exoplanet studies is new tools that allow scientists to discover worlds much more easily than before.

A new generation of exoplanet search tools began with the launch of the (now retired) Kepler Space Telescope in 2009. That telescope’s work was followed by subsequent instruments, one of which was NASA’s Transiting Exoplanet Survey Satellite, also known as TESS. Launched in 2018, NASA recently released some of TESS’ achievement figures from its first five years in space. During this time, TESS has discovered an impressive 329 new exoplanets, as well as discovering thousands more exoplanet candidates.

These candidates come from preliminary data indicating that a planet may exist, but more data is needed to verify that it does. To detect this, TESS monitors the sky and collects images with a total of 192 million pixels. With one such image being collected every 30 minutes or less. TESS collects a lot of data. “The volume of high-quality TESS data available now is quite impressive,” said TESS project scientist Knicole Colón SlashgearSaturday (22/4).

“We have over 251 terabytes for just one of the key data products, which is called a full frame image. It is equivalent to streaming 167,000 films in full HD resolution,” he continued.

It’s not easy to find planets orbiting distant stars. Because planets are so small and dim compared to the stars that orbit them, it’s rare for telescopes to observe planets directly. Instead, astronomers use telescopes to observe the stars around which planets orbit, which are called parent stars. By observing changes in the host star, they can learn whether or not planets are there.

TESS uses an exoplanet detection method called the transit method. That method is one where you look at the brightness of a certain star over time. If any planet orbits the star as it passes through the space between the telescope and the star (called a transit), the brightness of the star will drop very slightly. If you observe the dips in brightness regularly, you can tell if a planet is there and how fast it is orbiting the star. The magnitude of the decrease in brightness can also help provide information about things like a planet’s size or orbit as well.

However, to see this decrease in brightness, you need to observe the star in question at several different points. First you need to look at the stars at their usual brightness, then during the transit, then after the transit. And scientists will observe these transits several times so they can be sure that what they are seeing is really caused by the presence of the planet and nothing else. That’s why TESS collects so much data – because it needs to observe lots of stars and look at them at multiple points in time to tell if they have planets orbiting them.

The way researchers get data from telescopes to see changes in a star’s brightness is by using a shape called a light curve. These figures plot the decrease in a star’s brightness over time, indicating when a planet may pass in front of the star. The data is taken from a large view of most of the sky that TESS captures every night.

“This system and large data bank have allowed TESS to identify a large number of exoplanets,” said Christina Hedges, lead of TESS’s Office of the General Investigator.

But there are other reasons why a star might get brighter, such as if there is a supernova explosion, so TESS has also observed hundreds of supernovae over its time. Some of the exoplanets found by TESS are in the habitable zone, which is the region around a star where liquid water could exist on a planet’s surface, so it’s possible that worlds where we might find life have already been discovered by TESS. TESS has already completed its two-year primary mission and is now on an extended mission, but is still operating so well that we can expect TESS to continue discovering many more exoplanets in the next few years.