Get ready, America. The Moon is about to eat the Sun.
Astronomer and blogger Phil Plait is getting excited about “The Great American Solar Eclipse of August 21, 2017”:
This eclipse is a big deal.
For one thing, total solar eclipses in any given spot on the Earth are rare. They happen roughly once or twice a year somewhere on Earth, but it’s a big planet, and a lot of it is hard to reach. 70% is ocean, and a lot of what’s left of the real estate is taken up by places like the Arctic and Antarctic. So getting a total solar eclipse over, say, the U.S. doesn’t happen often. The last one was in 1979, and that one cut a shallow chord across the northwest.
For another, total solar eclipses are one of the most beautiful, wondrous, awe-inspiring sights nature provides for us. The Moon slowly covers the Sun, taking nearly 90 minutes. In the last seconds before the Sun is totally covered, the sky grows dark, the air cools, birds fooled into thinking night has fallen stop singing … and then the moment arrives.
Totality. The last bit of solar surface is blocked by the Moon, and the glory of the corona is revealed.
Plait provides a wonderful eclipse primer on his Bad Astronomy blog (one of my favorites) and includes an informative video from his PBS series “Crash Course Astronomy.” As you can see on the map from Space.com below, Southwestern Pennsylvania will not be within the narrow path of totality, so we will only get to view a partial solar eclipse.
Calla Cofield reminds us that looking directly at the sun, even during a solar eclipse, is dangerous:
Your parents probably told you to NEVER look directly at the sun with your naked eye. In fact, you’ve probably been told that by lots of reputable sources (including our own Space.com). But according to NASA and four other science and medical organizations, it’s OK to look at a total solar eclipse with the naked eye — but only when the face of the sun is totally obscured by the moon.
Plait explains further:
Yes, looking at the Sun is dangerous. Duh. The light is very intense, and looking at the Sun for more than a moment can damage your retina. In general, the damage is localized to small parts of the retina, and you won’t go completely blind (but you can permanently damage those parts, creating black spots in your vision). This is called solar retinopathy, and in many cases —though not all— the damage gets better over time. You likely won’t go permanently, completely blind by looking at the Sun, but long-term damage is certainly possible.
So why risk it? Don’t look directly at the Sun.
However, to be clear: Looking at the eclipse when it is total is safe; the Sun is completely blocked by the Moon and the corona is only about as bright as the full Moon. But the partial phases before and after totality are not safe to look at.
We all know how curious kids can be, especially if their interest is piqued by the growing coverage in the news and on social media. Taking your eyes off them to watch the eclipse yourself, even for a brief moment, can be detrimental to their vision. Fortunately, NASA has some great advice for watching the eclipse safely:
The only safe way to look directly at the uneclipsed or partially eclipsed sun is through special-purpose solar filters, such as “eclipse glasses”… or hand-held solar viewers. Homemade filters or ordinary sunglasses, even very dark ones, are not safe for looking at the sun; they transmit thousands of times too much sunlight…
- Always inspect your solar filter before use; if scratched or damaged, discard it. Read and follow any instructions printed on or packaged with the filter.
- Always supervise children using solar filters.
- Stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the bright sun. After looking at the sun, turn away and remove your filter — do not remove it while looking at the sun.
- Do not look at the uneclipsed or partially eclipsed sun through an unfiltered camera, telescope, binoculars, or other optical device.
- Similarly, do not look at the sun through a camera, a telescope, binoculars, or any other optical device while using your eclipse glasses or hand-held solar viewer — the concentrated solar rays will damage the filter and enter your eye(s), causing serious injury.
- Seek expert advice from an astronomer before using a solar filter with a camera, a telescope, binoculars, or any other optical device. Note that solar filters must be attached to the front of any telescope, binoculars, camera lens, or other optics.
- If you are within the path of totality, remove your solar filter only when the moon completely covers the sun’s bright face and it suddenly gets quite dark. Experience totality, then, as soon as the bright sun begins to reappear, replace your solar viewer to look at the remaining partial phases.
- Outside the path of totality, you must always use a safe solar filter to view the sun directly.
- If you normally wear eyeglasses, keep them on. Put your eclipse glasses on over them, or hold your handheld viewer in front of them.
It’s extremely important that solar filters are compliant with the ISO 12312-2 safety standard, are less than three years old, and have no scratches on them.
If you can’t find solar filters for next Monday’s eclipse, there are other ways to safely view the action, including the old pinhole projector method (see instructions here). Bob Batz, Jr. has a bunch of other ideas and fun places to go to watch this celestial rarity here in Pittsburgh, where 81% of the Sun’s face will be covered by the moon:
The local hot spot to be for this one will be Carnegie Science Center on the North Shore, which is going all out with activities from 10 a.m. to 5 p.m. that Monday.
The partial eclipse is to start just after 1:10 p.m., with the maximum sun coverage happening just after 2:35 p.m. and lasting for about 2 minutes. Then the partial eclipse ends just after 3:55 p.m.
With admission, Science Center guests can safely view it on equipment including a solar telescope. They can also watch live video feeds of the total eclipse in other places in the Science Stage, with commentary by center experts. There’ll even be a chance to use a solar telescope to take a photo with your mobile phone.
For an additional $5 ($3 for members), guests can get reserved seats in Buhl Planetarium for live feeds with commentary plus other shows and demonstrations, and those tickets come with a set of eclipse glasses.
Let’s hope for clear skies and safe viewing. If you miss this one, you won’t have to wait too long for the next solar eclipse. On April 8, 2024, Erie will find itself in the path of totality!