Speaker 1: Welcome to brain Stuff from How Stuff Works. Hi, I'm
Speaker 1: Christian Seger, and this is brain Stuff. If you follow
Speaker 1: the latest in space gossip, you might have heard about
Speaker 1: a little rendezvous between a NASA probe called Dawn and
Speaker 1: an object in space known as the dwarf planet Series.
Speaker 1: This meet up is exciting news for space fanatics. But
Speaker 1: if you don't know what Series is, and at this
Speaker 1: point you're too afraid to ask, well, we are here
Speaker 1: to lay down the facts you need to know. Series
Speaker 1: first came to human attention when the Italian astronomer Giuseppe
Speaker 1: Piazzi spied a moving point of light from the Palermo
Speaker 1: Observatory on New Year's Day in eighteen o one. Yeah,
Speaker 1: eighteen o one. That means Series was actually discovered almost
Speaker 1: a hundred and thirty years before the former planet and
Speaker 1: now fellow dwarf planet, Pluto. Piazzi correctly deduced that the
Speaker 1: object was somewhere between the orbits of Mars and Jupiter.
Speaker 1: In reality, that zone contains the thing we now know
Speaker 1: as the asteroid Belt, a loose ring of rocky objects,
Speaker 1: of which Series is the largest. Piazzi named this new
Speaker 1: space dot after the Roman deity Series the goddess of
Speaker 1: grain and nutritious food crops. Historically, astronomers have gone back
Speaker 1: and forth about the status of this object. Piazzi himself
Speaker 1: initially thought it might be a comet. It has also
Speaker 1: been known as a planet and as an asteroid, but
Speaker 1: today astronomers classify Series as a dwarf planet. So you
Speaker 1: might be wondering what makes a dwarf planet different from,
Speaker 1: you know, a regular planet or a comet or an asteroid. Well,
Speaker 1: according to the International Astronomical Union, a dwarf planet is
Speaker 1: any object that meets the following four criteria. First, it
Speaker 1: goes around the Sun. Okay, that's a check for Series. Two,
Speaker 1: it's not a moon. Another check for Series. Even though
Speaker 1: they're not moons, death stars and other space stations are
Speaker 1: implicitly disqualified. Three, it has attained hydrostatic equilibrium. This means
Speaker 1: the object has enough mass that over time, the force
Speaker 1: of gravity has shaped it roughly into a sphere. This
Speaker 1: would disqualify all those comets and asteroids that are shaped
Speaker 1: like lumpy potatoes. Series is pleasantly, almost delightfully round. And
Speaker 1: number four, it has not, as astronomers say, cleared the
Speaker 1: neighborhood around its orbit. Over time, large bodies like planets
Speaker 1: tend to eliminate other materials from their orbital zone. This
Speaker 1: is why objects like Series and Pluto art planets. They
Speaker 1: haven't cleaned for room. For Series. That room is the
Speaker 1: asteroid belt, frankly, just about the dirtiest room in the
Speaker 1: Solar System apart from the icy pig sty that is
Speaker 1: the Kuiper Belt. So Series remains a dwarf planet, but
Speaker 1: there is no means anything wrong with being a dwarf
Speaker 1: planet because Series is fascinating. Here are a couple of
Speaker 1: quick facts. Series is about nine hundred and fifty kilometers
Speaker 1: or five d ninety miles in diameter, meaning if you
Speaker 1: look at the disk head on, it is about the
Speaker 1: size of Texas. But it's total surface area is about
Speaker 1: two point eight million square kilometers or about one point
Speaker 1: one million square miles. That's about as much real estate
Speaker 1: as the country of Argentina. By itself. Series accounts for
Speaker 1: a quarter of the mass of the entire asteroid belt.
Speaker 1: If you were to take a cross section of Series,
Speaker 1: you would find a rocky core at the center and
Speaker 1: a dusty outer crust on the surface, but in between
Speaker 1: them a subterranean mantle of water ice. This layer of
Speaker 1: water ice has drawn a lot of attention, since anywhere
Speaker 1: there is water, there's always the slim possibility that we
Speaker 1: could discover life. Scientists sometimes speak of Series as a
Speaker 1: proto planet or an embryonic planet. About four and a
Speaker 1: half billion years ago, when the planets in our Solar
Speaker 1: system were first forming, Jupiter's gravity prevented Series from becoming
Speaker 1: a full fledged planet. This left it frozen in its
Speaker 1: fetal state, so there may be a lot we can
Speaker 1: learn from Series about how planets are born in young
Speaker 1: solar systems. Check out the brainstuff channel on YouTube, and
Speaker 1: for more on this and thousands of other topics, visit
Speaker 1: how stuff works dot com.