The next full moon will create a lunar triangle that will be visible from San Diego this week.

When the full moon rises on Tuesday at 7:34 p.m. ET in September, it will not only be a supermoon, but it will also be this year’s Harvest Moon, coinciding with a partial lunar eclipse.

Below is a look at what makes this month’s Super Harvest Moon partial lunar eclipse so special.

What is a supermoon?

A supermoon occurs when a full moon phase synchronizes with a particularly close orbit around the Earth. This typically occurs only three or four times a year and in succession, given the moon’s ever-changing, oval-shaped orbit.

A supermoon is obviously not bigger, but it can appear that way.

This supermoon will be about 222,000 miles from Earth. The next one will be in October.

What is a Harvest Moon?

A Harvest Moon occurs once a year, usually in September or October, depending on which full moon falls closest to the autumnal equinox. This year, the autumnal equinox falls on September 22.

The name originated in a time before electricity, when farmers relied on the moon’s light to harvest crops late into the night before winter set in, according to NASA. The harvest moon’s illumination was especially important to farmers in the fall, when they could harvest the most crops.

Each month’s full moon may also have Native American names that relate to crops harvested under that month’s moon. September’s moon has also become known as the Corn Moon. Europeans may call it the Fruit Moon or the Barley Moon.

What is a lunar eclipse?

A partial lunar eclipse is also expected to be visible to people in North America, South America, Africa, and Europe. A partial lunar eclipse occurs when the Earth passes between the moon and the sun, casting a shadow on the moon.

Will the lunar eclipse be visible in San Diego?

Only a small portion of the moon will be obscured by this eclipse. At the peak of the eclipse, the moon will only look as if a small bite has been taken out of its northwest corner.

The moon is close to the horizon, so if you want to see the eclipse it is important that you have a good view towards the east.

Visibility also depends on weather conditions. Get your First Alert Forecast here.

What time is the ‘supermoon eclipse’?

The penumbra eclipse — when the moon is in the Earth’s outer shadow — begins around 5:41 p.m. for San Diego. During that phase, the moon will become slightly darker.

The umbra, or inner shadow of the Earth, will begin to eclipse the Moon at about 7:12 p.m.

The maximum eclipse, which will have a magnitude of only 0.085 to 1 for San Diego, is expected to occur at 7:44 p.m.

The entire eclipse will last nearly three hours, ending at 9:47 p.m.

Do I need to wear safety glasses?

Unlike solar eclipses, you don’t need to wear protective glasses for a lunar eclipse and can safely view it with the naked eye, NBC News reports.

When is the next lunar eclipse?

There will not be another solar eclipse in North America until March 13, 2025. On that date, a total lunar eclipse may occur in San Diego.