The first of only two supermoons of 2021 rises in a Super Pink Full Moon tonight (April 26) and you have a chance to watch it online if bad weather clouds out your view.
Supermoons are full moons that appear bigger in the sky than usual, though the difference may not be noticeable to the casual observer. During a supermoon, the full moon can appear up to 14% larger and 30% brighter than when it is at its farthest from Earth. That’s because it coincides with the moon's arrival at perigee, the closest point to Earth in its orbit.
The Virtual Telescope Project led by astrophysicist Gianluca Masi will offer a free live webcast of the supermoon over Ceccano, Italy today at 1:15 p.m. EDT (1715 GMT), but only if good weather permits. You can watch it live here.
April Full Moon 2021: 'Super Pink Moon' rises Monday
See the Super Pink Moon? Let us know in our April full moon forum here!
During the April full moon tonight and early Tuesday, the moon will be about 222,064 miles (357,378 kilometers) away from Earth, that is about 8% closer than the distance of an average full moon (240,000 miles or 384,400 km). This fluctuation in the full moon's distance is caused by the fact that the moon's orbit around the Earth isn't perfectly circular but very slightly elliptical. If the full moon occurs closer to the perigee (the closest point to Earth on this slightly elliptical orbit), it can appear bigger than if it occurs closer to the apogee (the farthest point).
"Different publications use slightly different thresholds for deciding which full moons qualify as supermoons, but for 2021 all agree the two full moons in April and May are supermoons," NASA's Gordon Johnston wrote in a guide (opens in new tab).
April full moon is also called the Pink Moon, but it has nothing to do with its color. According to NASA, the April moon got its name after the herb pink moss, also known as creeping phlox, moss phlox or mountain phlox, which is one of the earliest spring flowers appearing in the United States.
While the Pink Moon is technically full on Monday, it will appear full in the sky to casual observers for three days, from Sunday to Wednesday (April 25-28). It will reach its fullest phase Monday night at 11:32 p.m. EDT (03:32 a.m. GMT).
If you miss the April supermoon, don’t despair. The next one on May 26, will be even a little closer to the Earth and therefore slightly bigger, although the difference will still probably be impossible to spot.
"These two full Moons are virtually tied, with the full moon on May 26, 2021, slightly closer to the Earth than the full moon on April 26, 2021, but only by about 98 miles (157 kilometers), or about 0.04% of the distance from the Earth to the moon at perigee," Johnston wrote.