Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey, brain Stuff,
Speaker 1: Lauren vogelbaumb here. You've probably noticed that when you look
Speaker 1: up at the Moon, you always see the same features.
Speaker 1: You can see craters and patches of lighter and darker areas.
Speaker 1: With a pair of binoculars or a telescope, you can
Speaker 1: make out even more detail. But no matter how you
Speaker 1: look at the moon, you're always seeing the same landscape.
Speaker 1: But the Moon is a sphere. If we're only seeing
Speaker 1: one hemisphere, then what's on the other side. This is
Speaker 1: the so called dark side of the moon, the side
Speaker 1: we never see because it always faces away from Earth.
Speaker 1: For this reason, people also use the phrase the dark
Speaker 1: side of the Moon to describe something mysterious or unknown.
Speaker 1: This side of the Moon faces the cold, black, expansive space.
Speaker 1: What could be on this side of the moon? And
Speaker 1: is it really always dark? We actually know what it
Speaker 1: looks like, and no, it is not permanently dark. We
Speaker 1: have lots of images from various lunar missions, and in
Speaker 1: nineteen sixty eight, astronauts aboard the Apollo eight spacecraft were
Speaker 1: the first humans to set eyes on it in person.
Speaker 1: But the popularity of the phrase means that there is
Speaker 1: ample opportunity for people to jump to the wrong conclusion,
Speaker 1: especially since we only ever see that one hemisphere, and
Speaker 1: it's easy to misunderstand the cause of the phases of
Speaker 1: the moon that we see from Earth. But mostly this
Speaker 1: is a problem with terminology. The descriptor dark side suggests
Speaker 1: that shadows perpetually cloak the surface of the side of
Speaker 1: the Moon that faces away from us. It's fun to
Speaker 1: imagine a dividing line between the light side and the
Speaker 1: dark side, but that's not how it works. While it
Speaker 1: is true that some part of the Moon is dark
Speaker 1: at any particular or time, it's not always the same part.
Speaker 1: That's because like Earth, the Moon rotates on its axis,
Speaker 1: a meaning it has a daytime and a night time.
Speaker 1: So if you were to set up camp on the
Speaker 1: Moon and stay put, you would eventually see the sun
Speaker 1: rise and fall. You'd experience both day and night. So
Speaker 1: technically the moon does have a dark side at any
Speaker 1: given moment, but it shifts. The dark side is the
Speaker 1: part currently experiencing night. The side of the moon we
Speaker 1: see is sometimes the day side, sometimes the night side,
Speaker 1: and sometimes a bit of both. A more accurate term
Speaker 1: to describe The side of the Moon that we always
Speaker 1: see is the near side. The side opposite is the
Speaker 1: far side. The near side will always be facing toward us,
Speaker 1: and the far side will always face away. This is
Speaker 1: true from anywhere on Earth. If you were to fly
Speaker 1: from America to Australia or vice versa, you'd see the
Speaker 1: same features that you're familiar with back home. But why
Speaker 1: do we only ever see one side of the Moon
Speaker 1: from Earth? Okay, it takes about twenty nine days for
Speaker 1: the Moon to make one complete orbit around the Earth.
Speaker 1: That's also how long it takes the Moon to make
Speaker 1: one rotation on its axis. Because the Moon's rotation and
Speaker 1: orbit take the same amount of time, we always see
Speaker 1: the same face of the Moon no matter when we
Speaker 1: look at it. The Moon just keeps spinning the same
Speaker 1: side of itself toward us as it orbits around us.
Speaker 1: This happens because of gravity. Earth's gravitational pull on the
Speaker 1: Moon is so strong that our planets slowed the Moon's
Speaker 1: rotation down to its current speed. Its rotational speed is
Speaker 1: locked with the time that it takes to orbit the Earth. Interestingly,
Speaker 1: the Moon is doing the same thing to the Earth,
Speaker 1: just much slower because the pull of the Moon on
Speaker 1: the Earth is much smaller, so if you've ever felt
Speaker 1: like the days are getting longer, they are technically still.
Speaker 1: In a few billion years, the Earth's rotation will match
Speaker 1: the time it takes the Moon to orbit the Earth.
Speaker 1: By that time, the Moon and the Earth will have
Speaker 1: drifted apart from each other a little bit, which means
Speaker 1: it'll take a little longer for the Moon to travel
Speaker 1: around the Earth, to the tune of about forty days
Speaker 1: or so, meaning that in the distant future, one Earth
Speaker 1: day will equal forty of our current Earth days, or
Speaker 1: about nine hundred and sixty hours. Once the Earth's rotation
Speaker 1: matches the time it takes for the Moon to orbit
Speaker 1: the Earth, the same side of the Earth will face
Speaker 1: the Moon all the time. But okay, let's talk about
Speaker 1: the phases of the moon. A common misconception about the
Speaker 1: moon is that it appears as just a sliver sometimes
Speaker 1: called a new moon, when the Earth is between the
Speaker 1: Sun and the Moon, thus blocking the light from the
Speaker 1: Sun and casting a shadow across the moon. But in reality,
Speaker 1: during a new moon, the Moon is between the Sun
Speaker 1: and the Earth. Imagine that you're in a room that's
Speaker 1: dark except for one window that has sunlight shining into it,
Speaker 1: and then someone walks between you and the window. You
Speaker 1: would see the person in silhouette. They'd appear mostly shadowy,
Speaker 1: but with a bright outline along their side facing the window.
Speaker 1: That's exactly what a new moon is. A full moon,
Speaker 1: in contrast, is when the Earth is between the Moon
Speaker 1: and the sun. Going back to our example, imagine that
Speaker 1: you're the person standing by the window. If you turn
Speaker 1: to look into the room, anyone standing there would be
Speaker 1: well illuminated. That's the same as us looking at a
Speaker 1: full moon. But again, whether it's a full moon or
Speaker 1: a new moon, you're still looking at the same side
Speaker 1: of the moon, the near side. During a new moon,
Speaker 1: you're looking at the near side during lunar night time,
Speaker 1: and during a full moon you're looking at the near
Speaker 1: sides version of noon. All of this being said, the
Speaker 1: far side of the moon is still a little mysterious
Speaker 1: because the Moon's bulk blocks radio signals to and from
Speaker 1: the Earth from its far side. Engineers don't yet have
Speaker 1: a good way for us to explore that far side.
Speaker 1: In the future, we may see NASA and other organizations
Speaker 1: build radio relay towers on the Moon's surface to make
Speaker 1: exploration possible. Until then, we'll have to content ourselves with
Speaker 1: being looney over the side that faces us. Today's episode
Speaker 1: is based on the article what and Where is the
Speaker 1: Dark Side of the Moon on HowStuffWorks dot com written
Speaker 1: by Jonathan Strickland. Brain Stuff is production of iHeartRadio in
Speaker 1: partnership with hostuffworks dot Com and is produced by Tyler
Speaker 1: klang A. Four more podcasts my heart Radio, visit the
Speaker 1: iHeartRadio app, Apple Podcasts, or wherever you listen to your
Speaker 1: favorite shows.