A partial lunar eclipse of September’s Super Harvest Moon is coming up, which you can watch online for free.

On Tuesday (September 17), the full Harvest Moon will bring about a partial lunar eclipse that will be visible from North and South America (except Alaska), Europe, most of Africa, western Asia, and parts of Antarctica. This eclipse will occur during a “supermoon,” which makes the moon appear slightly larger in the night sky. This occurs when the moon is slightly closer to Earth, which happens because the moon’s orbit is slightly elliptical, or oval-shaped.