Looking Up: August’s Partial Solar Eclipse
After a full day of enjoying nature and the great outdoors, it’s time to unwind after sunset. Taking advantage of the pristine dark skies of Northeastern Ontario, you set out the blanket or lawn chair and look up in amazement. While stargazing this month, you might notice a higher number of meteors than usual. Earth is now at the peak of one of the best celestial shows around, the Perseid Meteor Shower.
But the night sky isn’t the only thing of interest this month–there are day time events, too!
The Solar Eclipse
The long awaited total solar eclipse visible over North America occurs on August 21. Unlike a lunar eclipse when the moon moves into Earth’s shadow, turning a copper orange colour and is completely safe for look at, a solar eclipse involves looking directly at the Sun. The perfect geometric line up of the sun-moon-earth produces a thin 112 km wide dark path of totality on Earth, stretching across fourteen states from Oregon to South Carolina. Areas to the north and south of the line of totality will see a partial phase with Northeastern Ontario seeing about 63% coverage.
Extreme precautions must be taken if you plan to observe and photograph this event. NEVER LOOK AT THE SUN WITHOUT PROPER PROTECTION. There are various online sources that sell eclipse glasses to wear, and Baader solar filter sheets to place at the front end of a telescope, binoculars or camera lens. Even the sensitive CCD chip in many cameras and smart phones can be damaged if not adequately filtered. Unprotected eyes can lead to eye damage or even blindness.
Never make or use home made filters found on the internet, except a pinhole projection camera in which you safely observe an image at the back end of a shoe box. Trees will cast hundreds of projections on the ground. Dark sunglasses that claim to have UV protection will not protect your eyes. Purchasing a 4.5 by 5.5 inch piece of number 14 grade welder’s glass from a local supply dealer is ideal for viewing the eclipse, but the glass quality will not yield sharp photographic images.
While not truly rare, eclipses are infrequent. The solar shadow is produced somewhere in Earth every 18 months on average. The type of eclipse depends on the Moon’s distance from Earth which ranges from 356,000 to 406,000 km. The closer the Moon, the longer the period of totality which in this case will last for 2 minutes and 41 seconds on the eclipse line. For Northeastern Ontario first contact (or when the Moon begins to cover the Sun) will occur at 1:17 pm. Mid-eclipse occurs at 2:35 pm, and last contact will be at 3:48 pm. The next total eclipse will take place on April 8, 2024 and travel close to the St. Lawrence Seaway.
The Perseid Meteor Shower
As comets round the Sun, dust and outgases are blown off of these icy mountains by the solar wind. This forms a lingering dusty tail in space. If this debris cloud intersects Earth’s path, we encounter it the same time each year like a race car crossing the finish line of a track. The meteor shower lasts from July 17 to August 24 ,with the peak or highest number of meteors seen on the night of August 12 into the morning of the 13th.
The Perseids are known to produce about 100 meteors per hour with sand sized particles striking our atmosphere at 59 km/sec. Unfortunately, the waning gibbous moon will rise around 11 pm. Its 71% lit surface will cast a glow in the sky and wash out the fainter meteors, thus reducing the visible hourly rate. The good news is this is a weekend event. All meteor showers are spectacular so plan to observe the Perseids!
The Milky Way & More
August is also a wonderful time to enjoy late summer and early fall sky watching across Northeastern Ontario. Starting from the south in Sagittarius, the gorgeous Milky Way stretches directly overhead by midnight. Scanning with binoculars, you will be lost in a sea of stars. One of the most beautiful globular star clusters is located in the constellation Hercules. Catalogued as simply M13, this “snowball” of stars is estimated to contain as many as one million suns.
It’s an easy target in binoculars and lonely in a telescope but you can probably spot it with the unaided eye on very dark nights. M13 is an estimated 25,000 light years away. New moon occurs on August 12, September 20 and October 19. Full moons will be the: Sturgeon Moon on August 7, the Harvest Moon on September 6 and the Hunter’s Moon on October 5.
Until next time, clear skies everyone.
Gary Boyle is past President of the Ottawa Centre of the Royal Astronomical Society of Canada and has been interviewed numerous times on Canadian radio stations. Gary is an astronomy educator and lecturer with a never ending passion for the night sky. The International Astronomical Union has officially named asteroid (22406) Garyboyle for his dedication to public education and the RASC over the past decades.
Look for the International Space Station passing near or over: