Pale Blue Dot
Sphere Demo
©2016 Pacific Science Center
Written by Joy DeLyria
Edited by Dave Cuomo
This script is based upon work supported by NASA Astrobiology Institute under Cooperative
Agreement No. NNA13AA93A. Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s) and do not necessarily reflect the views
of the National Aeronautics and Space Administration.
Terms of use:
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These materials are for non-commercial use only, and cannot be sold.
These materials are for your organization’s internal use only. Additional
requests should be made before sharing beyond your organization.
If these materials or a portion of these materials are copied as is, please
credit as follows: “Pale Blue Dot demonstration created by Pacific Science
Center, NASA Astrobiology Institute under Cooperative Agreement No.
NNA13AA93A.”
If new activities are created that are based on this original activity, please
credit as follows: "Activity modified from Pale Blue Dot demonstration
created by Pacific Science Center, NASA Astrobiology Institute under
Cooperative Agreement No. NNA13AA93A.”
Description
Pale Blue Dot is a live, 20 minute demo, featuring Science on a
Sphere, a dynamic interactive data modeling tool. In this show, our
guests will explore the different ways Earth can be viewed from
space. Using hands-on props and interaction with a live science
interpreter they will learn how scientists find planets orbiting
different stars. They will explore what Earth might look like from
these interstellar distances.
Props and Materials
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I-Pad
Small Earth on a Stick
Small Jupiter on a Stick
Datasets
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Blue Marble
Pale Blue Dot PIP 1
Pale Blue Dot PIP 2
X-Ray Sun
Earth as Exoplanet
X-Ray Sun
Blue Marble
Venus
Real-time Weather (IR-Clouds)
Real-Time Surface Temperature
Blue Marble
Sunset/water glare PIP
Earth With Glint
Earthlike Planet
What you say
Hey everyone welcome to Science on a Sphere and
the Pale Blue Dot, my name is _______. How are
you all doing today?
Great, so I was wondering have any of you ever
seen the Earth from space?
Really, you’ve been to space? Oh you meant
you’ve seen a picture of the Earth from space. Yes
very cool. As a matter of fact what we are looking
at here is a picture of Earth from space. It’s called
the Blue Marble and it took NASA six months to
create this image. They had a satellite orbiting the
Earth, over both poles, and taking pictures of the
surface from over 400 miles away. They wanted
the entire planet cloud free and it took six months
to get that. They then pieced that mosaic together,
added a generic cloudy day and created this true
color image of Earth. That is what your eyes would
see if you could see the Earth from space. The
blues would be that color blue, the greens that
green the browns that brown.
Let’s see if we can find Seattle. Oh look, there it is,
it seems to be under a cloud….
Now, just over 30 years ago scientists took another
picture of Earth but it was a little further away. A
scientist by the name of Carl Sagan convinced the
team in charge of the Voyager 2 spacecraft to turn
it towards Eath and take a picture. At the time
Voyager 2 was traveling by Neptune over 3 billion
miles from home.
So are you guys ready to see a picture of Earth
taken from further away than any other? Are you?
Well here you go!
What is Displayed
Blue Marble
Pretty cool huh?
What? Can’t you see it?
Here let me point it out.
Pale Blue Dot
There it is, the Earth. The red streaks are the glare
of the Sun. From the orbit of Neptune the Earth is
seemingly so close to the Sun that the glare is
overwhelming.
As Carl Sagan said, “Look again at that dot. That's
here. That's home. That's us. On it everyone you
love, everyone you know, everyone you ever
heard of, every human being who ever was, lived
out their lives.” On that Pale Blue Dot.
Pretty interesting. But in the time since that
picture was taken scientists have started to find
worlds much further away than Neptune scientists
have found worlds orbiting other stars far, far
away from the Sun. We call these planets
Exoplanets and they can be hundreds of light years
away.
What would the Earth look like from there?
Well before we get to that let’s figure out how
scientists have found planets orbiting other stars.
Pale Blue Dot 2
So here is the sun.
And this is the Earth (hold up Earth stick). These
are actually the right size compared to each other.
If the Sun where the size of the sphere then the
Earth would be only this size.
Let me ask you a question, where do you think the
Earth would be at this scale?
Hmm. Well you would have to take the Earth just
outside of the Science Center and over to the
Space Needle.
Here is Jupiter. It’s also the right size too but it
would have to be even further away. You would
have to take this all the way to Pike Place.
Now who wants to help me demonstrate one of
the ways scientists can find exoplanets.
Okay what’s your name?
Take the Earth and hold it up high above your
head. Now start walking around the sphere. Walk
at a normal pace.
Now while you do that I’m going to walk around
with Jupiter. Now since I am further from the Sun
I’m less affected by its gravity so I am going to be
walking slower.
Let’s say we were looking at the Earth from
another star. If we were looking at the Sun, when
the planets passed in front of it the light would
dim just a little bit, but a measurable bit. If we
detected that dimming consistently and
repeatedly we could detect the planets.
And that is how scientists using the Kepler space
telescope have detected potentially 2,000 planets
orbiting other stars. To give you an idea of how
sensitive that instrument is. Imagine going to the
top of the Space Needle and looking toward New
York City. Imagine your friend is on top of the
Empire State Building with a flashlight. Imagine
that you could detect not only the light from the
flashlight, but would notice the dimming caused by
a flea walking across it.
What would the Earth look like from so far away?
Well scientists at the University of Washington
have put together this image of what the Earth
would look like if it were an exoplanet. If we could
see the Earth from hundreds of light years away
what we would see is a single pixel.
Can we possibly tell anything from so far away?
X-Ray Sun
Earth As Exoplanet
Well we talked about how we can detect these
planets. Could we learn anything else? Let’s get
another volunteer. You take Earth and I’ll take
Jupiter.
Hold Earth up high. Which planet would block
more light from the star? That’s right Jupiter. So
we could tell how big a planet is. That’s important
because scientists think that the bigger a planet is
the less likely it is to have ground to walk on. The
big, big, planets are all gas!
Now I am going slower so an observer from far
away could tell that I take longer to transit the sun.
They could calculate the speed.
Now here is a cool thing. By looking at the color of
light coming from the star scientists can tell how
hot it is and if you know how hot a star is you can
calculate the star’s mass. If you know how fast a
planet is moving around that star you know how
far away it is from the star.
No matter if we are talking about a really hot or a
cool star what happens to water if you get too
close to it? That’s right it boils away. Also even if a
star is super-hot if a planet is too far away water
will freeze.
So using the same method that scientists found
the planet they can also tell how big it is and
whether water could exist.
Is there anything else we can tell from that pixel of
light?
Let’s look at Earth. As we look is it the same color
all over is it different? That’s right it’s different.
What color is the water? How about the land? So
as the Earth turns we might see differences in
color based on what we are looking at.
Here’s Venus.
As we look at Venus does it change color like the
Earth does? No it doesn’t.
Does it change in brightness?
Here is the Earth again. This is showing the
weather for the last 30 days. Notice how the
brightness changes? That’s because of the clouds
moving, because of weather! If we noticed a
change in brightness coming from that single pixel
of light it could tell us whether that distant planet
had an atmosphere with weather.
Other information we get from light is
temperature. Here is an image that shows the
changing temperature here on Earth as seen from
space. Satellites in orbit around both poles can
eventually image the entire surface of Earth. These
satellites carry instruments that detect microwave.
Microwaves are a type of light that like infrared
can give us information about temperature.
Let’s take a look at the Earth again. Do you think
the water or the land reflect more light? That’s
right the water. The other day I was out by Puget
Sound at sunset. I noticed that the light would be
brighter off of the water than off of the land, and
brighter off of the water between me and the sun.
It’s called glint.
Well if an alien planet had water on it, and was
rotating we would be able to see that glint shining
off of the water. So we could possibly tell, from
that little pixel of light, whether that planet, very
far away had liquid on its surface.
To an Astrobiologist (that’s a scientist who studies
the possibility of life in the universe) water is
everything because all the life we know of
depends on water.
So here it is, what we are looking for. An Earthlike
planet orbiting another star. We haven’t found it
yet, but we are looking. And we have a better
understanding of how we might find it.
And that is a Pale Blue Dot, thank you for coming
to the science center today.
EARTH With Glint