When Is the Full Moon in July 2021 and Why Is It Called the Buck or Thunder Moon?

This month's full moon is due to cross the sky this week and is expected to peak on the night of July 23, appearing opposite the Sun at 10:37 p.m. EDT.

Due to the curvature of the Earth this time will vary depending on location, meaning some people around the world will see the peak full moon on Saturday instead.

In any case, the moon will appear full for about three days from Thursday to Sunday, according to former NASA executive Gordon Johnston.

The full moons of each monthhave historically been given different names in Native American cultures, while other names come from Colonial American or European sources. Traditional names for full moon tend to refer to natural phenomena that coincide with the month or season in which they appear.

These names are listed by The Old Farmer's Almanac, which states that July's full moon is known as the buck moon.

The name "buck moon" is thought to refer to the antlers of male deer—also called bucks—which are particularly large at this time of year. Deer grow and shed their antlers every year.

The Old Farmer's Almanac notes that some other names for the July full moon include the salmon moon, a Tlingit name referring to when fish returned to the area, and thunder moon, a term attributed to the Western Abenaki people, which refers to stormy weather.

The moon looks full at certain times of the month because of the amount of sunlight it reflects towards the Earth. When a full moon occurs, sunlight is hitting the side of the moon that is facing Earth, so we see a whole side.

But at other times, sunlight is only hitting a small part of the moon that we can see, or no parts at all. This is why we can sometimes only see a small part of the moon in the sky.

The amount of sunlight that hits the moon is always changing because the moon orbits the Earth. It takes the moon around one month to do a full circle around our planet.

The full moon is not the only skywatching opportunity that will take place this summer.

The planets Jupiter and Saturn are both due to be at their closest and brightest for the year next month. Saturn will appear brightest on August 2, while Jupiter will appear brightest on August 19.

NASA's Johnston said in a blog post that "with clear skies and a backyard telescope" it should be possible to see Saturn's rings and four of Jupiter's moons.

Meanwhile, the Perseid meteor shower is currently active and is expected to peak in the afternoon of August 12, EDT—though people may also be able to experience this peak in the early morning or the following early morning when there are darker darker skies.

In ideal conditions the Perseid shower can see 100 meteors streak across the sky every hour.

Full moon
A full moon rises over southern England in the U.K., on January 2019. The moon appears full at certain times of the month because of reflected sunlight. Richard Heathcote/Getty