Here’s a quick look at what’s going on in the sky during the month of May, 2015:
All times Eastern Daylight and based on Northern Hemisphere viewing:
May 3 — Full Moon, 11:42 p.m. The visible Moon is fully illuminated by direct sunlight. Though the Moon is only technically in this phase for a few seconds, it is considered “full” for the entire day of the event, and appears full for three days. May’s full Moon is called the Full Flower Moon. Learn about the folklore surrounding May’s full Moon in this quick video.
May 4 – 5 — Get outside and see if you can get a view of the Eta Aquarid Meteor Shower! The best viewing is between 2 a.m. and 4 a.m., looking to the southeast. The Eta Aquarids get their name because their radiant lies within the constellation Aquarius, near one of the constellation’s brightest stars, Eta Aquarii. Unfortunately, the nearly-full, waning gibbous Moon may obstruct viewing of these showers.
May 5 — The Moon and Saturn will be very close together in the night sky. Saturn will rise a few hours after the sun sets each evening. Look to the southeast to see the waning gibbous moon rise first, then Saturn, which will follow the Moon high in the sky. See if you can locate the bright, reddish-hued star Antares, which will join the pair. The bright, waning gibbous Moon will also be close to the blue-white star, Spica. To find Spica, just remember a little mnemonic device popular among stargazers: “Follow the arc to Arcturus and drive a spike to Spica.” Huh? Simple. Find the Big Dipper, and follow the curve of its handle down to Arcturus. From Arcturus, it’s a straight line in the same direction to reach Spica. You’ll always find the star Spica in the same place in the sky throughout the month of May every year.
May 6 — Heliacal setting* of Aldebaran. Aldebaran is a giant orange star, about 40 times larger than our own Sun, and is the brightest star in the constellation Taurus, located on the bull’s head.
May 11 — Last Quarter Moon, 6:36 a.m. At this phase, the Moon appears half full. One-half of the Moon is illuminated by direct sunlight while the illuminated part is decreasing, on its way to the New Moon phase. Learn more about the Moon phases here.
May 13 — The Moon is in ascending node. This is the point at which the Moon’s orbit crosses, from south to north, the plane of the Earth’s orbit.
May 14 — The sliver of the waning crescent Moon is at perigee (its closest point to the Earth).
May 16 — Heliacal setting* of Sirius. Sirius is the brightest of all stars in the night sky. It appears as a single star, but it is actually a star system. Sirius, also known as the “dog star” is part of the constellation Canis Major.
May 17 — Heliacal setting* of Betelgeuse. Betelgeuse (pronounced “Beetle Juice”) is located in “The Armpit of the Giant” Orion, and shines with a ruddy red hue, almost 500 light years away. It is an irregular pulsating supergiant star, nearing the end of its life, and because of this, it expands and contracts spasmodically. Its diameter can vary between 550 and 920 times that of the Sun!
May 18 — New Moon, 12:13 a.m. The Moon is not illuminated by direct sunlight and is completely invisible to the naked eye.
May 19 — Look for a tiny sliver of the waxing crescent Moon low in the west, below Venus. Start looking after the Sun sets.
May 22 — Saturn in opposition. A body in space is at opposition when it sits 180° from the Sun in relationship to the Earth. This is the best time to view a superior planet – one beyond the Earth’s orbit.
May 23 — Saturn closest to Earth, the closest it will be in 2015. The waxing crescent Moon is also very close to Jupiter.
May 24 — Heliacal rising** of Formalhaut. Fomalhaut is sometimes referred to as the Loneliest Star. Its planet, Fomalhaut b, was the first beyond our solar system to be visible to the human eye. The Hubble Space Telescope has captured very clear images of Fomalhaut b, planet about three times the size of Jupiter located approximately 25 light years away.
May 25 — First Quarter Moon, 1:19 p.m. At this phase, the Moon appears half full. One-half of the Moon is illuminated by direct sunlight while the illuminated part is increasing.
May 26 — Venus, and the star Castor will be very close together. Castor is one of the starts within the “twins” of the constellation Gemini. Castor, also known as Alpha Geminorum, sits to the right next to his twin, Pollux, or Beta Geminorum. (Read more about them here). The Moon is at apogee (its farthest point to the Earth).
May 27 —The waxing gibbous Moon is in descending node. This is the point at which the Moon’s orbit crosses, from north to south, the plane of the Earth’s orbit.
May 30 — Mercury in lower conjunction. A planet (or asteroid or comet) is simply said to be in conjunction when it is in close alignment with the Sun, as seen from the Earth.
* Heliacal Setting: When a star is overtaken by the sun and is lost in in its rays.
** Heliacal Rising: The rising of a celestial object at the same time, or just before the Sun, or its first visible rising after a period of invisibility due to conjunction with the Sun.