The enormous object sits just 20 light-years from Earth.
The planets could have similar light and temperature conditions to those that may have existed when life first emerged on Earth.
TESS may uncover planets that have the right conditions for life to exist.
A stable climate could be key to hosting life.
A year on these planets flies by, lasting between five and 10 Earth days.
The test photo includes more than 200,000 stars.
Helium is the second most common element in the universe, but more than a decade of searching for the gas in the atmospheres of exoplanets has proven unsuccessful, until now.
TESS stands for Transiting Exoplanet Survey Satellite, and its mission is to identify planets orbiting the brightest stars in our neighborhood of the universe.
TESS will scour the skies for signs of undiscovered worlds.
Scientists are excited about the prospect the mission holds for new discoveries, but if you're just learning about the mission now, here's what you need to know.
"It's just completely bizarre that we should have two planets the same size but opposite ends of the habitability spectrum."
The planet is likely the densest Earth-sized planet ever found.
"This is an enormous challenge," Hawking said in the film. "To leave Earth will take a global approach and everyone should join in."
The spacecraft has spotted almost three-quarters of the alien planets scientists have identified to date.
The dust could be evidence of evolving infant exoplanets.
Although the flare lasted just 10 seconds, it made the star appear about 1,000 times brighter than usual.
The numbers contradict everything we know about how moons form.
An intriguing feature of its orbit ties this telescope's destiny to a lunar schedule.