Summer nighy sky features Perseids, blue moon, planets, milky way

The Perseid Meteor shower — Aug. 11 and 12

In my experience, the highlight of every summer is the annual Perseid meteor shower, which peaks on the evenings of Aug. 11 and 12 this year. This is consistently the year’s best meteor display, and the fact that it occurs on typically mild nights makes it one of the more comfortable to watch.

Each year at this time Earth passes through debris streams of particles that litter the path of periodic comet Swift-Tuttle, which orbits the sun in a long, looping path every 133 years. Discovered in July 1862 by astronomers Lewis Swift and Horace Tuttle, the comet was linked to the Perseids in 1866 by the Italian astronomer Giovanni Schiaparelli. Subsequent searching of ancient records first mention the shower in the year 36.

The Perseids are active from mid-July to the end of August. Their name derives from the point in the sky where the shower members seem to radiate from in the constellation of Perseus, which climbs into the northeastern sky after midnight.

The Perseids are swift and often leave persistent streaks of “trains” for a few seconds after flashing across the sky. A single observer at a dark site can expect to see up to 100 Perseids at the peak time early on the morning of the 12th. The waxing moon will set by 1 a.m. local time, giving you a few hours of quality darkness.

The return of the planets

It’s been a while since we have had bright planets gracing our sky, but that is about to change. Late evening and early morning sky watchers will have a number of our fellow solar system wanderers to keep track of.

For most of July and August the action takes place in the morning sky, where you will find Saturn, Mars and Jupiter. Saturn rises first, cresting the southeast horizon at around midnight in mid-July and by 9 p.m. in mid-August. Saturn reaches opposition, rising at sunset and setting at sunrise, on Sept. 8.

Saturn is approaching one of its equinoxes, which happen every 15 years, and its famous rings are now tipped at a very small angle to Earth. They will appear as two spikes framing the disc of the planet.

Ruddy Mars and bright Jupiter greet early risers in morning twilight throughout July, but they will both be well-placed in the eastern sky for viewing by folks wishing to catch the Perseids. On the morning of Aug. 14, the two planets will pass in close conjunction, just one-third of a degree apart.

Venus gets into the act by mid-August, gradually appearing in the west as evening twilight begins. As we move into September the dazzling planet will gradually pull ahead of the sun. As fall gets underway it will climb to a position of prominence in the evening sky for the rest of the year.

Don’t forget the Milky Way!

The backdrop for all summer stargazing is the luminous band that traces the star-studded Milky Way, the brightest parts of which arc majestically overhead as summer wanes to fall. That amorphous glow that you see from dark sky locations is the combined light of some of the hundreds of billions of stars that accompany our sun in a great cosmic spiral swirl.

Three bright stars, Vega, Deneb, and Altair, form the Summer Triangle grouping, which is split by some of the galaxy’s brightest star clouds. Binoculars or a small low-power telescope will begin to break these clouds up into individual stars and clusters as well as show glowing emission nebulae.

There will be four full moons between the summer solstice and the autumnal equinox. These will occur this Saturday (Strawberry Moon), July 21 (Full Buck Moon), Aug. 19 (Full Sturgeon Moon), and Sept. 17 (Harvest Moon).

Having four full moons in a single season is unusual; typically there are only three. This leads to one of the definitions of “Blue Moon,” which, according to an account in the 1937 edition of the Maine Farmer’s Almanac, labels the third full Moon of a season as the “Blue Moon.” The more popular definition calls the second full Moon in a calendar month the “Blue Moon.” This last occurred in August 2023.

Partial lunar eclipse — Sept. 18

Summer holds one last treat for us just before the fall equinox. The full moon on Sept. 17 will look a bit odd as the shadow of the Earth brushes its northern polar regions in a small partial lunar eclipse. Mid-eclipse occurs at 10:44 p.m. Eastern time in Washington, at which time about eight percent of the moon will be obscured.