TESS WATCHES A COMET (AND VARIABLE STARS AND MARS AND BUNCH OF ASTEROIDS) GO BY

Phil Plait

NASA's Transiting Exoplanet Survey Satellite — TESS — has begun scientific operations. That means it is now sweeping the sky, looking at millions and millions of stars, searching for telltale dips in light that indicate planets are orbiting those stars.

You can read up on how it will do that in an earlier article I wrote, and even get a taste for what it will see in an article about First Light, when it first opened its metaphorical eye to the heavens.

On July 25, before science observations had begun and TESS was still taking images for calibration and testing, it took a series of observations over the course of 17 hours that prove to be pretty dang cool. TESS points in the direction more-or-less opposite the Sun in the sky, and on that date it just so happened that a faint comet, C/2018 N1 (NEOWISE) was passing through that region. Well, faint to those of us on Earth, but TESS has pretty sensitive cameras on board, and so the comet looks rather bright.

NASA made a video of the observations. Watch!

This video is compiled from a series of images taken on July 25 by the Transiting Exoplanet Survey Satellite. The angular extent of the widest field of view is six degrees. Visible in the images are the comet C/2018 N1, asteroids, variable stars, asteroids and reflected light from Mars.