NASA's new
planet-hunting space telescope TESS has been inserted into its orbit around
Earth, and has just started its job of scanning the skies to look for planets
beyond the Solar System.
On July 25, TESS took 17 hours' worth of observations. This was to test its ability to collect a "prolonged set of stable periodic images covering a broad region of the sky," NASA wrote.
But before
it even started work, NASA turned it on to do a few test observations - and it
just so happened to catch a perfectly little comet in the act of streaking
across the sky.

On July 25, TESS took 17 hours' worth of observations. This was to test its ability to collect a "prolonged set of stable periodic images covering a broad region of the sky," NASA wrote.
During these
observations, TESS managed to snap a series of images of a comet named C/2018
N1 - first discovered less than a month earlier, on June 29.
The comet is
located about 48 million kilometres (29 million miles) from Earth, and in the
images taken by TESS, it's seen moving across the southern constellation Piscis
Austrinus. Its comet tail can be seen extending towards the top of the image.
You may also
notice the stars appearing to shift between black and white. This is a result
of image processing, and it helps highlight variable stars, which change in
brightness because of their rapid rotation, pulsation, or eclipsing binary
companions.
The white
dots are asteroids, and a "wave" of light moving across the image
from left to right at the end of the sequence is caused by light reflecting off
Mars, which is outside the frame. The entire sequence shows just a small
fraction of TESS' field of view.
This ability
to stare at wide regions of the sky for long periods of time is the key TESS
will rely on as it looks for planets. This is because of the method it uses -
the clue is in the telescope's name, the Transiting Exoplanet Survey Satellite.
It hunts for
exoplanets using what is called the transit method. This is because when an
orbiting planet moves between us and its star, it causes a slight dip in the
star's light. By staring for long periods at the sky, TESS will be able to
capture these changes.
It only
works for systems in which the orbital plane is aligned the correct way - if
the flat side of the plane is facing us, rather than its edge, there are other
detection methods available - but the transit method is really effective. It
led to the detection of thousands of exoplanets by TESS' predecessor, Kepler.
TESS is more
sensitive than Kepler, so it's expected that it will bring home some serious
exoplanet bacon.
Immediately
after taking these observations, TESS' science operations started, so hopefully
we'll start seeing some cool exoplanet news soon.
You can read
more about TESS on its NASA website, and follow its news on Twitter.
Via
Scienalert.
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