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KIDS: Our World!
EVAN: What’s that Globey?
What am I doing? I’m looking into the night sky.
Oh, what’s with the white beard?
I’m doing my impersonation of Galileo.
Galileo was an Italian physicist, mathematician,
and astronomer who studied the stars more than 400 years ago.
People today refer to Galileo as the "father of modern
science” and the “father of modern observational astronomy."
Galileo made major improvements to the telescope, which today
continues to help us see the stars and planets in space.
In fact, using one of his early models of the telescope,
Galileo was able to discover four of the largest moons of
Jupiter, which are called Io, Europa, Callisto, and Ganymede.
He was also the first to say our Moon’s surface is not smooth.
It’s rough and uneven... covered with craters and mountains.
Like Galileo, today’s astronomers continue to look
into space, hoping to make new discoveries about our universe.
But today’s telescopes are much more powerful than the one’s Galileo used.
The large telescopes our astronomers use can be found at observatories around the world.
But they can also be found in space, such as the Hubble Space Telescope.
Hubble is a giant telescope that orbits Earth and sends
back amazing pictures of our universe.
Today we’re going to talk about a special earth-based observatory in Puerto Rico.
It’s the Arecibo observatory. It’s called that because it’s
located near the town of Arecibo in Puerto Rico, which is a US territory.
Puerto Rico is in the Caribbean. It’s also an island.
The telescope at the Arecibo observatory is enormous!
It measures 305 meters in diameter.
That’s about 1,000 feet, which is even longer than three football fields.
A diameter is a line segment that goes from one point on a
circle through the center to another point on the circle.
People use this measurement to describe how large a circle is.
But the Arecibo telescope isn’t like some of the other telescopes we’ve talked about.
You know, there are many different types of telescopes,
and only some of them are optical scopes like the on used by Galileo.
The Arecibo telescope is a radio telescope, which means it
sees the radio waves given off by large objects like planets.
A large dish on the Arecibo telescope focuses these waves
so the radio data can be collected.
Computers than turn the data into images or pictures.
Radio waves are not nearly as affected by Earth’s atmosphere as optical telescopes.
So it’s not necessary to build a radio telescope on a high mountain.
In fact, the Arecibo telescope was built inside a giant natural valley.
The largest curved telescope dish in the world makes it the
most sensitive radio telescope on Earth!
DR. KELLY HERBST: Well, a radio wave is a wave just like you think about waves on the ocean.
A wave goes up and then it goes down.
Well a radio wave isn’t in the water, it’s actually a kind of light.
So it’s light just like we think of light from the Sun or
light from a lamp that we would turn on. Those also are waves.
But in this case, it’s a radio wave.
EVAN: Radio waves are much longer, and lower in energy than visible light.
DR. KELLY HERBST: Now a radio wave can travel through space
just like light waves can travel through space, because radio is light.
And that’s the advantage of a radio telescope. That wave can
travel through space, but then when it gets to the Earth,
it can make it all the way down through our atmosphere.
The atmosphere of the earth actually blocks a lot of
different kinds of light that comes to us from space.
But there is what we call a window of transmission at radio frequencies.
So radio waves can come from space and make it all the way
down to the ground where we can detect them.
EVAN: Astronomers carefully chose the location of the Arecibo telescope.
Puerto Rico is near the equator. The equator is an
imaginary line that runs around the center of Earth.
You may have noticed that objects in the sky, like stars
or the moon, appear in different locations at
different times of the night. This happens because Earth is
actually rotating on its axis as it revolves around the sun.
It would be impossible to move a telescope as big as the one
at Arecibo to follow these objects, so placing the
telescope near the equator lets astronomers observe planets and
other objects in space for the longest period of time.
DR. KELLY HERBST: A telescope that’s really really big is
really really hard to move. So rather than make a moving telescope,
the Arecibo telescope is fixed, it doesn’t move.
It sits in the ground and we can’t reposition it.
So that means the telescope can only look at whatever passes right over it.
Well, if you want to be able to look at planets and you can
only see what’s straight overhead, you need to be close to the equator.
Because near the Earth’s equator, planets pass directly overhead.
EVAN: Astronomers have learned many things from using this giant telescope.
For example, astronomers used to believe it took Mercury 88
days to make one complete rotation on its axis.
Every 24 hours marks one day on Earth. That’s the time it takes
Earth to make one complete rotation on its imaginary axis.
When scientists began studying Mercury’s radio signal in 1965,
they discovered that one day on Mercury is only 59 Earth days long.
That’s really slow compared to Earth but much faster than astronomers first thought.
But it’s not just planets that interest scientists at Arecibo.
Much about what we know about the upper layers of our
atmosphere has been learned from the research done in Puerto Rico.
And here’s something really cool. The Arecibo telescope is
part of the SETI program, which stands for the “search for extraterrestrial intelligence.”
DR. KELLY HERBST: The SETI program is a scientific
program designed to look to see if there are any other living
beings out in space somewhere. They actually found pulsars and
thought that those pulsars might be signals from alien civilizations.
It turned out they were just stars. But in 1974, when the
Arecibo telescope was recomissioned after an upgrade,
they decided to do what’s called an active SETI test.
And they sent a message out into space to a star cluster
that’s about 25,000 light years away.
That means it will take the message 25,000 years to get there.
And if anybody’s there to answer it, it will take their
answer 25,00 years to come back. So searching for life out in space is not easy.
EVAN: Wow Globey, can you imagine how incredible it would
be if one of our telescopes actually discovered life outside Earth?
After all, our astronomers, with the help of the Arecibo
and Hubble telescopes, as well as other observatories on
Earth, are discovering new planets in our solar system and beyond.
What else will they discover in the next 10, 20, 30 or 400 years?
It will certainly be exciting. So what do you think Globey, should I keep the beard?
GLOBEY: NO!
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KIDS: Our World!