Belmont’s Resident Astrophysicists Ready For Monday’s Big Eclipse

Photo: Belmont’s resident astrophysicists, Steven Saar and Andrea Prestwich, ready for Monday’s solar eclipse.

Andrea Prestwich is approaching viewing Monday’s total solar eclipse of two minds. As an astrophysicist at Harvard’s Smithsonian Astrophysical Observatory who explores the vastness of space through an orbital x-ray telescope – the Chandra X-ray Observatory – the coming eclipse is, well, disappointing ordinary.

“The rational part of me is underwhelmed. This whole event is just a shadow, after all!” said Prestwich, who is a member of the Belmont School Committee. “It is nowhere near as significant as, say, the discovery of gravitational waves or cosmic X-ray sources.”

But by Monday afternoon, Prestwich said she’ll revert to her five-year-old self who first discovered an interest in the heavens.

“The kid in me is wildly excited! I get to see the [sun’s] corona with my own eyeballs!”

Monday will be a special day for Prestwich and her husband, Steven Saar, who happens to be the other astrophysicist in the family – working at the Harvard-Smithsonian Center for Astrophysics – as it will be the first time either has witnessed a total solar eclipse.

For Saar, the blotting out of the sun Monday is something akin to his line of research as a member of the Solar and Stellar X-Ray Group, researchers who study solar and stellar atmospheres.

Saar and Prestwich joined the Belmontonian via e-mail from Boone County, Missouri, to discuss the upcoming solar eclipse.

Belmontonian: What’s happening on Monday afternoon, Aug. 21?

Saar: A total eclipse of the Sun, when the moon completely covers the disk of the Sun for at least some viewers on Earth. It is the first total eclipse to pass over the US since 1991, where one clipped Hawaii. Before that, you have to go back to 1979 to find one hitting the continental US (and then only in the Pacific Northwest).

It doesn’t happen very often, because the moon’s orbit around the Earth is slightly inclined to our motion around the Sun, and so not only must the Earth, moon, and Sun all line up, but the moon must also be at this “crossing point” in its orbit. In Belmont, we are a little off from this perfect alignment, [so] the Sun will still be about 60 percent covered, and look like a crescent.”

Belmontonian: Have you seen a total solar eclipse before? What are your memories?

Saar: I’ve seen several partial eclipses like what [will occur] in Belmont … but the only total eclipse I tried to see was in Helsinki, Finland in 1990. Unfortunately, it was totally cloudy. I did get to see the shadow of the moon rushing across the sky from horizon to horizon, and hear the crickets start chirping, thinking night had fallen.

Andrea: This is my first total eclipse! My research is more X-ray astronomy/black hole populations, and I haven’t ever needed an eclipse to do science.

Belmontonian: As astrophysicists, is the run-of-the mill total solar eclipse interesting compared to black holes and the creation of galaxies?

Saar: Since eclipses come fairly rarely, each new one is a chance to try out newly developed instruments and equipment that can do and see new things that were impossible in previous eclipses. For example, in this eclipse, some members of our solar group at the Harvard-Smithsonian Center for Astrophysics located in Cambridge are flying a brand new instrument aboard a NASA jet to measure the magnetic field in the solar corona. The magnetic field is what confines the corona’s hot, electrified plasma into the beautiful filaments you see sprouting out from the Sun during the eclipse, but they are very weak and have not been measured directly before.

Andrea: Total eclipses are very interesting from a historical perspective. In 1919 the British astronomer Sir Arthur Eddington used a total eclipse to measure the positions of stars near the sun to show that light was being bent by the sun’s gravity, a key prediction of Einstein’s General Theory of Relativity. On occasions when eclipses are mentioned in ancient texts, they can be used as a chronometer to pin down the exact date of the event which otherwise can be open to interpretation.

Bemontonian: What will expert scientists be looking at that most sky gazers might miss?

Saar: Since it will be my first “total”, I will be enjoying the sheer beauty of it like everyone else: the flower-like corona, Bailey’s beads (a string of glowing dots caused when the last bit of sunlight before totality sneaks past the edge of the moon in lunar canyons and craters seen on edge), the diamond ring (when these beads merge into a thin ring with glowing “jewels” where more Sun is getting past). There will also be several planets visible during totality: Mars Venus, Mercury, and Jupiter will all pop into view once the blinding Sun is covered. And I might steal a glance at the ground during totality; I’m told that you can get some faint shimmery effects due to diffraction around the moon, but this has been hard to capture on film.

Prestwich: I’m looking out for all of the above and the expressions on our kid’s faces!

Belmontonian; What would you advise people to experience or keep in mind when they see the (partial) eclipse in and around Belmont?

Saar: Never look at the Sun directly without the protection of certified eclipse glasses! Normal sunglasses are NOT sufficient. You can permanently damage your retina! Noone wants a sun-sized blind spot permanently etched in their field of vision. Learn how to make a simple pinhole camera (plenty of websites give details, and practice beforehand!). This can be a very effective way of seeing the eclipse.

The [peak] of the eclipse will be about 2:45 p.m. in Belmont, but the duration of the lunar passage will last about two-and-a-half hours altogether.

Prestwich: I thoroughly recommend the Smithsonian Eclipse App, available free for IOS and Android. This app was put together by colleagues at the Harvard-Smithsonian Center for Astrophysics and includes cool stuff like an interactive eclipse map, views of the sun from solar observatories, and NASA live stream of the event.

Belmontonian: Where will you be?

Saar: In Columbia, Missouri with our family. We’re having an eclipse holiday!

Belmontonian: What if it’s cloudy?

Saar: The day before we will study the local weather carefully, and be prepared to drive a bit to a clearer spot if needed. If we can’t get to one, we will pout a lot, but still, enjoy the natural phenomena that are still visible.

Prestwich: We’ll watch it on the SAO App!

Steve to Andrea: Nerd.

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