Lots of planets around neighboring stars are not seen directly. Instead, they are found when they temporarily pass in front of their parent star, an event called a transit. During the transit they block out a little bit of light from the star, essentially casting a shadow to Earth-watchers. Astronomers learn a lot from these transient events. They can measure the planet's orbital period, study its atmosphere, and estimate its size. What's tricky is that the planet may only graze the edge of the star during a transit, giving an inaccurate measurement of its diameter. One such nearby exoplanet, LTT 1445Ac, only 22 light-years away, was first identified by NASA's Transiting Exoplanet Survey Satellite (TESS). But TESS does not have the required optical resolution to pin down the planet's exact diameter by refining its trajectory across the face of a star. Along came Hubble with its sharp vision to precisely measure the planet's diameter to be only 1.07 times Earth's diameter. This makes it a cousin of Earth in terms of size. But that's where all similarity ends. LTT 1445Ac is too close to its red dwarf sun for habitability. Surface temperatures are roughly 500 degrees Fahrenheit – the temperatures inside a pizza oven.