REGINA BARBER: Throughout history, there have been things that have happened in the sky that have made people uneasy. Think comets and eclipses or when a new star appears in the sky. The skies were always there, and so when things changed, it confused people and sometimes led people to see these events as omens. Of course, there are scientific explanations behind these astronomical phenomena. So joining me today to explain is my guest, Dr. Samaiyah Farid, solar physicist and project scientist at the University Corporation for Atmospheric Research in Boulder, Colorado. Welcome to Science Friday.

SAMAIYAH FARID: Thank you. Thank you for having me.

REGINA BARBER: All right. So we’re going to start talking omens. Let’s start with an event that is actually super fascinating to me, the supernova of 1054. So a Chinese astronomer has documented sightings of this, and Native Americans may have seen it too based on rock paintings that have been found in Arizona and New Mexico. But first, before we jump into the science, can you explain what that would have looked like in the sky?

SAMAIYAH FARID: Yeah. So imagine if you were an astronomer in 1054. These guys were not just casual observers of the sky. They made very detailed maps of the star locations across different seasons. So all of a sudden, there’s one location that we see a star that wasn’t there the previous night.

And then it stays over some period of time, over two years that this supernova was observed. So from Earth, they probably observed a bright region that looked like a star, just a bright light coming from this one location in the sky that was dark before.

REGINA BARBER: Yeah. It was brighter than Venus, right, at one point.

SAMAIYAH FARID: Yeah.

REGINA BARBER: And it was actually– you could see it in the daytime for almost a month. OK. So can you go through the process of what that actually was. It was a supernova. It was an explosion of a star. So what happens to that star before it explodes?

SAMAIYAH FARID: Yeah. It was formed from an eruption of a pulsar, which is a really rapidly spinning star. And once that star reached the end of its life, it exploded and caused the supernova to be observed from Earth.

REGINA BARBER: And that explosion created the Crab Nebula, right? Can you explain what that is?

SAMAIYAH FARID: Right. Exactly. So when we see the Crab Nebula now, it’s a really amazing area of dust and gas that looks sparse and fibrous. So what happens is the star that exploded, this is all the gas and debris from that star and the effect of heating the local gas also nearby.

REGINA BARBER: Let’s move on to an astronomical phenomenon that some people may have witnessed with their own eyes, an eclipse. So throughout history, there have been lots of reactions to eclipses. In ancient China, there was a myth associated with eclipses. A celestial dragon attacked and ate the sun. In the Incan culture, eclipses were associated with the sun god expressing his displeasure. What is actually happening during an eclipse?

SAMAIYAH FARID: It depends. So when you’re talking about a solar eclipse, the alignment happens when the moon moves in between the sun and the Earth. It casts a shadow on the Earth. And so we observe it as a solar eclipse. On the other side, the lunar eclipse, which can be observed more often than solar eclipses, happen when the moon moves into the Earth’s shadow. So then the moon is on the other side of the Earth, and it moves into the Earth’s shadow. And so when we view it from Earth, it looks like the moon itself is being eclipsed or darkened.

REGINA BARBER: Right. So that’s the type of eclipse that’s extra fascinating for me. It’s called the blood moon sometimes. It’s when it has that darkening that you talk about. It’s kind of reddish. It’s kind of creepy. There were actually four blood moons between 2014 and 2015. And this led to something called the Blood Moon Prophecies from two American Christian preachers thinking it was the end of times. So like you were saying, what makes this blood moon different from the other types of eclipses?

SAMAIYAH FARID: When we look at the moon in general from the Earth, the light that you see illuminating the moon’s surface is from the sun. But when the moon is in the Earth’s shadow, then a lot of the light that is from the sun is being blocked. So some of the sunlight still reaches the surface of the moon indirectly.

So it’s being scattered off of the Earth’s atmosphere. And so because it’s being scattered, it’s similar to a sunset. When you see the sun is going down, the colors you see there are the oranges and reds. And so the same effect is happening.

REGINA BARBER: Let’s move to another phenomenon that people may have been lucky enough to see even recently, comets. So in 1456, Halley’s Comet was ex-communicated by the Pope for being an instrument of the devil. And in the Incan and Aztec empires, they were seen as divine wrath against Spanish colonists. So Samaiyah, what exactly is a comet?

SAMAIYAH FARID: A comet is a large object. It’s made of dust, ice, and rock that orbits the sun, just like the planets do. A lot of these rocks and dust are leftover from the formation of the solar system.

REGINA BARBER: That’s all the time we have for now. And I want to thank my guest, Dr. Samaiyah Farid, solar physicist and project scientist at the University Corporation for Atmospheric Research in Boulder, Colorado. Thank you so much for joining us.

SAMAIYAH FARID: Thank you for having me.

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