Here's how and when to watch the harvest moon -- and what makes it so special

Harvest moonBill Ingalls/NASA via Getty ImagesThe 2013 Harvest Moon in Washington, DC.

Don’t forget to look outside at sunset on Thursday.

The 2017 harvest moon will rise just after the sun sets on October 5, appearing in the waning light.

This particular moon tends to appear massive and often takes on a reddish-orange colour, not unlike a “great pumpkin,” as NASA explains.

While it might appear to be a cosmic signifier of fall, the changes in colour are due to the effects of clouds and dust in the sky. And the harvest moon’s seemingly enormous size is due to an optical effect known as the “moon illusion,” which makes low-hanging moons appear to be much larger than they will when they rise higher into the sky.

The thing that gives the phenomenon the name “harvest moon” is simply the fact that this is the closest full moon to the autumnal equinox, which happened on September 22. This is a rare type of harvest moon, however, since it’s appearing in October, not September.

To watch it, you just need a clear view of the sky. In New York City, the sun will set on October 5 at 6:31 p.m. ET and the moon will rise at 6:51 p.m. ET. You can check your local exact sunset and moonrise times here.

For a preview, check out the sky tonight. You’ll still see an almost-full moon rising at a similar (though slightly earlier) time. Often, some of these harvest moon traits can be observed for a few days before and after the main event.

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