This week, a partial lunar eclipse of September’s Harvest Moon could create a spectacle in the night sky.

If skies are clear, the eclipse will be visible over North America on Tuesday, Sept. 17, beginning around 8:40 p.m., according to Space.com. The eclipse takes place during a “supermoon,” which is when the moon appears slightly larger in the sky.

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A supermoon occurs when the full moon coincides with the moon’s closest approach to Earth in its orbit, making it appear a bit brighter and closer than it usually does. This year has four supermoons in a row, in August, September, October and November. 

Tuesday’s full moon is called the Harvest Moon because it is the full moon that occurs closest to the start of autumn, dating back to when farmers depended on the moon’s light to harvest crops late into the night.

A lunar eclipse happens when the Earth passes between the sun and moon, casting a shadow on the moon. Tuesday’s spectacle will be a partial lunar eclipse, which means it will be an imperfect alignment of the sun, Earth and moon and the shadow will never entirely cover the moon.

“You’ll see a little bite taken out of one side of the Moon over about an hour,” NASA’s Preston Dyches wrote.

This will be the final lunar eclipse of the year. No eye protection is needed to view a lunar eclipse, unlike in a solar eclipse — like the one that took place across North America in April. The weather forecast for Philadelphia calls for rain Tuesday night, so if cloudy skies block views of the eclipse, there are live streams available online.