A rare blue moon will light up the sky this weekend — with a twist. Here's how to see it.

A rare blue moon is set to illuminate the skies this weekend — although it won't actually be blue.

The celestial phenomenon is expected to peak on May 31, marking the month's second full moon after the flower moon on May 1.

It will also coincide with a micromoon, meaning the moon will be near the farthest point in its orbit from Earth and may appear slightly smaller than usual.

Here is all you need to know about when to see it.

What time will the blue moon peak?

The 2026 blue moon will reach peak illumination at 4:45 a.m. ET on May 31, although it will appear full from the night of May 30.

It should be visible without telescopes or special equipment, weather permitting. Skywatchers will get the best views away from city lights and under clear skies.

Venus and Jupiter should be visible in the western sky about an hour after sunset, according to AccuWeather, while Mars and Saturn are expected to appear in the eastern sky about an hour before daybreak.

What color is a blue moon?

Despite the name, the blue moon will look much like any other full moon.

The phrase refers to the timing of the lunar cycle, rather than the moon's color. A blue moon is the second full moon in a single calendar month.

According to Encyclopedia Britannica, the term originated in the 16th-century expression "the moon is blue," which meant something impossible. The phrase "once in a blue moon" is now used to describe a rare event.

How rare are blue moons?

This weekend's lunar event will be a relatively uncommon occurrence.

Calendar blue moons occur roughly every two to three years, according to NASA. The last one appeared in August 2023, and another won't occur again until 2028.

The phenomenon happens because the lunar cycle lasts about 29.5 days — slightly shorter than most calendar months — which occasionally allows two full moons to occur in a single month.

There is also another type of blue moon, sometimes called a seasonal blue moon. This refers to the third full moon in a season containing four full moons. The next seasonal blue moon will be visible in May 2027.

What is a micromoon?

A micromoon occurs when the full moon is near the farthest point in its orbit around Earth.

Because of that greater distance, the moon can appear up to 14% smaller and about 30% dimmer than a supermoon, according to NASA. However, the difference will likely be subtle to the naked eye.

The combination of a blue moon and micromoon is relatively uncommon, making this weekend's event notable for skywatchers.