Night Sky: Globular Clusters and more highlights for June
A Good Month for Globular Clusters!
NASA defines globular clusters as “stable, tightly gravitationally bound clusters of tens of thousands to millions of stars found in a wide variety of galaxies.” That literally means a sphere of stars!
June will offer a chance to see two very beautiful examples of globular clusters with your naked eye. They both appear in the constellation, Hercules. On June 1, Hercules will be about 40 degrees above the Eastern Horizon at 9:00 p.m. It contains M13 and M92. Both clusters can be seen with the naked eye on clear calm nights! The following chart should help you find the constellations and clusters. (note: this chart is a reference aid and it needs to be rotated about 90 degrees to the left to match the orientation of the constellation at 9:00 p.m. on June 1.)
M13, the Hercules Globular Cluster is the larger and brighter of the two clusters. Prepared by Gerry Lebing.
M13 has a visual magnitude of +5.78 and is about 23 thousand light years away from us. It was discovered by Edmond Halley in 1714 and added to the Messier catalog in 1764. The cluster is believed to be 145 light years in diameter and contains about 500 thousand stars!
M92 was discovered by Johann Elert Bode in 1777. Messier independently found it in 1781, (remember, there was no internet or radio back then), and added it to his catalog. With a visual magnitude of +6.44, this is a tough object to see with the naked eye. It needs to be really dark and calm to make out the smudge of M92.
M92 is about 26 thousand light years away from us. It’s believed to be 100 light years in diameter and contains about 300 thousand stars.
What you can look for in June’s Night Skies
The evening skies offer a good opportunity to view M13 and M92 as well as other globular clusters. M5, which is almost as bright as M13, is another cluster you might be able to view with the naked eye. M10, M12, and M14 are also in the evening skies, but you will need binoculars or a telescope to see them.
Vega, the fifth brightest star in the sky, is visible in the evening skies. It will start the night about 20 degrees above the NE horizon. Vega is the brightest star in the constellation Lyra and is also called the Harp Star (ancient Greeks saw the constellation Lyra as the Harp of Orpheus.)
If you get up early to watch the sunrise, look for the row of planets starting with Saturn about 40 degrees above the Eastern horizon, followed by Mars and Mercury. Neptune is between Saturn and Mars and Uranus is between Mars and Mercury, but you’ll probably need binoculars to see those two distant planets. You might get to see Jupiter and Venus between Mercury and the Sun, but I think the sunrise will probably wash out both of those planets.
The June Bootids meteor shower peaks on June 27, but it’s usually a very weak shower, (1 to 2 shooting stars per hour). But, in 1998, it had an unexpected outburst of 100 shooting stars per hour. As the name suggests, the shower appears to originate from the constellation Bootes. At 12:00 a.m., Bootes will be about 50 degrees above the NW horizon. Look for the bright, red star Arcturus, which is the brightest star in Bootes.
Phases:
New Moon is June 6
1st Quarter is June 14
Full Moon is June 21
