Well, add another exoplanet to your "We better keep an eye on this one" list: TESS, the Transiting Exoplanet Survey Satellite, has found its first Earth-sized exoplanet orbiting in a star's habitable zone, where in principle, conditions could be ripe for life.
The planet, called TOI-700d, adds to a short list of planets that might be like Earth.
As always when I write about these, let me be very clear: The planet is the same size as Earth, and gets roughly the same amount of light and heat from its star as Earth does. However, we don't know its mass, its density, what it's made of, what its atmosphere is made of, if it even has an atmosphere, and more. So this planet might be Earth-like, or it might be like Mars. But it has checked off more than the usual things on the list.
The transit “light curves” (graphs of star brightness) for the three planets orbiting TOI-700 (b, c, and d from left to right). Each makes a noticeable dip as it blocks the star. The scale on the left is in tenths of a percent; for example, planets b and d block just less than 0.1% of ...