Next-generation planet hunter TESS is currently on a test run before it starts to do some proper science. But even during this “easy” task, NASA’s spacecraft has produced some stunning observations. In particular, the telescope was able to observe a comet that was only discovered a few weeks ago.
The object, known as comet C/2018 N1, was discovered by the NEOWISE (Near-Earth Object Wide-field Infrared Survey Explorer) satellite on June 29 and was observed by TESS on July 25. NEOWISE is dedicated to spotting asteroids and comets that might be orbiting near our planet. C/2018 N1 is located 48 million kilometers (29 million miles) from Earth, which is roughly a third of the distance between the Earth and the Sun.
The comet’s orbit passes between Earth and Mars, with the closest approach to the Sun taking place on August 2, 2018. The first observations suggest that the comet takes more than 10,000 years to complete a trip around our star. TESS observations, while not scientifically groundbreaking, show the comet's tail shift in position as it responds to the influence of the solar wind.
TESS will be hunting for exoplanets around 500,000 small stars using the transit method, which involves looking for subtle variations in the light from these stars. To achieve this, it is mandatory that the craft can produce stable periodic images over a broad region of the sky. The new observation, which includes just a tiny part of the telescope's field of view, shows what can be achieved with TESS.
And there's more to the image than just the comet. The telescope spotted plenty of stars, flickering in black and white as a result of the image-processing technique used. This flickering can help us spot variable stars, whose light might be changing due to either a companion star moving in front of them, or internal processes such as pulsation and rapid rotation. The image also shows some asteroids moving across the sky, as well as a ray of light reflected by Mars (not photographed).
TESS, which stands for Transiting Exoplanet Survey Satellite, has now completed its commission phase and begun its science operation in earnest. TESS is expected to detect more than 20,000 transiting exoplanets, including between 500 and 1,000 Earth-sized planets and super-Earths.