May 2023 kicks off with the Full Flower Moon and a spectacular Aquariid meteor shower peak on the following day. The May sky will also bring great views of globular star clusters Messier 4 and Messier 5. Finally, at the end of the month, Mercury's widest separation from the Sun occurs. This will provide a great opportunity to safely observe our closest neighbor.
(Looking to review last month's astronomy events? View April 2023)
Our highlighted list of astronomy events for May serves as your reference for key celestial experiences to expect and to plan for.
5 Astronomical Events in May 2023:
- Full Flower Moon - 5/5 @ 1:33pm EST
- Eta Aquariid meteor shower peak - 5/6
- Messier 5 is well placed - 5/12
- Messier 4 is well placed - 5/28
- Mercury at greatest western elongation - 5/29 @ 3:44am EST
For easy navigation, click on a specific event listed above to go directly to that section of the article. Below, we will explore each of these events in more detail.
Astronomy events to mark on your May 2023 calendar:
May 5th - Full Moon | Flower Moon
The Moon will reach peak illumination in its 29.5 day lunar cycle on Friday, May 5th at 1:33pm EST. This event occurs whenever the Moon's ecliptic longitude appears 180° away from the Sun's ecliptic longitude, as observed from Earth.
According to the Farmers' Almanac, in Native American cultures the Full Moon that occurs in May is referred to as the Flower Moon. The name is derived from the spring flowers that bloom during this period of time.
The Full Flower Moon will appear positioned in the Libra constellation at right ascension 14h47m30s and a declination of 17°11'S. Its angular size will be 31'24".
At this time, the Moon rises above the eastern horizon around sunset and set below the western horizon around sunrise the following day.
May 6th - Eta Aquariid meteor shower peak
The eta Aquariid meteor shower is active from April 19th to May 28th, and reaches its peak on Saturday, May 6th. Its radiant point, the area from which the shower appears to emanate, is positioned in the Aquarius constellation.
The meteor shower's ZHR will be 50, according to the American Meteor Society. ZHR is an abbreviation for Zenithal Hourly Rate and is defined by the hourly rate a meteor shower produces with a clear, dark sky, with the radiant at the zenith (highest point directly above the observer).
The eta Aquariid's were discovered in 1870 and originate from parent body 1P/Halley, or better known as Halley's Comet.
A few tips for viewing meteor showers:
- Do not direct your gaze solely towards the radiant point. The closer a meteor is in proximity to its radiant point, the more difficult it is to spot due to its shorter trail.
- Place yourself in a dark, secluded location away from light pollution and bright city lights.
- Allow for up to 30 minutes for your eyes to properly adjust to the dark environment.
- Make sure to dress appropriately for the weather.
- Bring a comfortable lawn chair to recline in or a blanket to lie back on.
- Try to observe as wide an area of the sky as possible. The broader your view of the sky, the higher the chance of catching a glimpse of a meteor whiz by.
May 12th - Messier 5 is well placed
Globular cluster Messier 5 (M5, NGC 5904) will reach its highest point in the sky on Friday, May 12th, around midnight local time.
This spheroidal conglomeration of stars, located in the Serpens constellation, will appear at magnitude +5.7 positioned at right ascension 15h18h30s and a declination of 2°04'N.
Messier 5, at +5.7 magnitude, will be too faint to be seen with the naked eye. However, with a pair of binoculars or a small telescope you will be able to witness this awe-inspiring celestial cluster.
M5 was discovered by German astronomer Gottfried Kirch on May 5, 1702.
May 28th - Messier 4 is well placed
Globular cluster Messier 4 (M4, NGC 6121) will reach its highest point in the sky on Sunday, May 28th, around midnight local time.
This spheroidal conglomeration of stars, located in the Scorpius constellation, will appear at magnitude +5.4 positioned at right ascension 16h23h30s and a declination of 26°31'S.
Messier 4, at +5.4 magnitude, will be too faint to be seen with the naked eye. However, with a pair of binoculars or a small telescope you will be able to witness this captivating celestial cluster.
M4 was discovered by French astronomer Jean-Philippe Loys de Cheseaux in 1745. It is located approximately 7,200 light-years away, making it the closest globular cluster to the Solar System.
May 29th - Mercury at greatest western elongation
Mercury will appear at its widest separation from the Sun on Tuesday, May 29th at 3:44pm EST. The planet will be positioned 24° west of the Sun shining at magnitude +0.4. This is referred to as its greatest western elongation. These wide separation moments occur roughly once every 3-4 months.
During the exact moment, Mercury will be positioned in the Aries constellation at right ascension 02h45m30s and a declination of 12°17'N.
Due to Mercury's close proximity to the Sun, the planet is often difficult to be safely observed because accidentally looking directly at the Sun can be damaging to your eyes. Additionally, the Sun's glare outshines any other celestial object that is in close proximity thus rendering them hard to view.
For stargazers, the exact dates of Mercury's greatest eastern elongation and its greatest western elongation are significant moments that provide an opportunity for optimal observations of the closest planet to the Sun.
At its greatest western elongation, Mercury will be visible before sunrise when it is shining in a thin crescent phase.
Plan your observations
Now that you have a better idea of the events in the night sky this month, the fun part is to actually observe them. Many of the events discussed above can be seen without special optical equipment. However, a quality pair of binoculars or a premium telescope will significantly enhance your viewing experience.
If you're in the market for purchasing or upgrading your astronomy gear, we have a curated selection of binoculars, telescopes and accessories from which to choose. Our online store offers high quality optics from industry-leading brands at value prices to help you explore the world above.