TELESCOPE AS TIME MACHINE
Read this article about NASA’s latest high-tech space telescope.
Then, have fun doing one or both of the word puzzles that use the important words in the article.
Then, have fun doing one or both of the word puzzles that use the important words in the article.
A TELESCOPE FOR (ALMOST) ALL TIME
If all goes as planned, the National Aeronautics and
Space Administration (NASA) has just launched a new
space telescope that will see back in time 80% of the way
to the Big Bang. The Big Bang is the colossal explosion
that gave the universe its start around 12 billion years ago
(give or take a few billion years). The Galaxy Evolution
Explorer, or GALEX for short, is an Earth-orbiting telescope
that is looking back 10 billion years to help scientists understand
how galaxies like our Milky Way came to be and how
they have changed over cosmic time. During its 29-month
mission, GALEX will survey nearly the entire sky and
gather galactic light that has been journeying toward us for
nearly the entire history of the universe
The Galaxy Evolution
Explorer (GALEX)
orbiting space telescope
will look back in time 10
billion years.
Explorer (GALEX)
orbiting space telescope
will look back in time 10
billion years.
GALAXIES 101
Galaxies are clusters of gas, dust, many different
types of stars in all different phases of their life cycles, and
various strange objects such as black holes. Our own
Milky Way galaxy contains over 200 billion stars, and the
entire universe probably contains over 100 billion galaxies.
Galaxies come in a huge variety of shapes and sizes.
Dwarf galaxies may contain as few as 10 million stars,
while massive galaxies may have a trillion (that’s a thousand
billion) stars. Shapes of galaxies may be spiral, elliptical, or irregular. Spiral galaxies have a large concentration of stars at
types of stars in all different phases of their life cycles, and
Milky Way galaxy contains over 200 billion stars, and the
entire universe probably contains over 100 billion galaxies.
Galaxies come in a huge variety of shapes and sizes.
Dwarf galaxies may contain as few as 10 million stars,
while massive galaxies may have a trillion (that’s a thousand
billion) stars. Shapes of galaxies may be spiral, elliptical, or irregular. Spiral galaxies have a large concentration of stars at
the center, called the “bulge,” and “arms” that extend
outward. Viewed face on, they often look like giant pinwheels.
The spiral arms are rich in gas and dust needed to
form new stars. Spiral galaxies that are sending out large
amounts of blue and ultraviolet light (more about this kind of
light later) tell scientists that a lot of new stars are forming.
Our galaxy, the Milky Way, is an average-sized, spiralshaped
galaxy and is forming new stars at a rate of one star
like our Sun every year.
outward. Viewed face on, they often look like giant pinwheels.
The spiral arms are rich in gas and dust needed to
form new stars. Spiral galaxies that are sending out large
amounts of blue and ultraviolet light (more about this kind of
light later) tell scientists that a lot of new stars are forming.
Our galaxy, the Milky Way, is an average-sized, spiralshaped
galaxy and is forming new stars at a rate of one star
like our Sun every year.
Elliptical galaxies range from spherical to cigarshaped.These galaxies don’t contain much gas, so are rarely seen to be forming new stars. Their red color tells scientists that they contain mostly old stars. Irregular
galaxies don’t have much structure and are generally smaller than spiral or elliptical galaxies.
BEYOND IMAGINATION’S LIMITS So how is looking at far away galaxies like lookingmiles per second), nothing travels faster than light. Even at
this speed, though, it still takes time for light to get from one
place to another. If you are looking at your girlfriend just
across the classroom, you are seeing her as she was a tiny
fraction of a second ago, rather than as she looks right now.
It takes about 8 minutes for light from the Sun to reach
Earth. The Voyager 1 spacecraft, which NASA launched
back in 1977, is now the farthest human-made object from
Earth. Even though this spacecraft is still inside our solar system, its signal, traveling at light speed, takes 12 hours to reach Earth! So, if Voyager’s signal takes that long to reach us, you can begin to imagine how long it takes light to reach us from far distant galaxies. What we are seeing of those galaxies is not how they look today, but how they looked when that now-very-old light left them, thousands or millions or billions
of years ago.
How will scientists know how old the light is that GALEX is receiving? Scientists know that the universe is expanding. Like a chocolate chip cake in the oven, space is the “cake batter” that keeps getting bigger and bigger, while the stars and galaxies are the “chocolate chips” that keep getting farther and farther apart. Like energy pulsing through the ocean, light energy travels in waves. As light waves travel through this expanding space, they get stretched out. The longer they spend traveling through space, the more stretched out they get. Because red light waves are longer than the light waves of other visible colors, scientists say that light coming
from distant stars and galaxies is “red-shifted.” The more red-shifted the light waves, the farther (and longer) they have traveled. GALEX is able to detect light that is extremely old, extremely red-shifted.
Like the Hubble Space Telescope that has given us so many awesome pictures of the universe, GALEX operates above Earth’s atmosphere, so gathers light that cannot
penetrate to telescopes on Earth’s surface. While the Hubble is used by many astronomers around the world to study very particular, tiny regions of the sky, GALEX has its very specific mission to look at nearly the whole sky, a goodly piece at a time. With the “all-sky survey” GALEX is making, scientists
will be able to see how galaxies in the early universe (far, far away) are different from galaxies of more recent times (relatively nearby). Because distant galaxies appear to us as they were millions or even billions of years ago, we can study how they evolve. We see what they looked like when
the universe was much younger, as galaxies were first forming. As we look at closer and closer galaxies we see how they change as they age, just as looking at babies, children, teenagers, and then adults can show how we humans change as we age.
MORE VIOLET THAN VIOLET?
GALEX is paying particular attention to how the universe looks in ultraviolet (UV) light. UV light waves are
not visible to humans. The shortest light waves that humans can see are blue or violet. Ultraviolet waves, as their names implies, are shorter than violet waves. These shorter waves carry more energy than do visible light waves (or the light waves that are longer than those we can see, like infrared and radio waves). Most of the UV light from the Sun is absorbed or scattered by Earth’s atmosphere, but what does get through to Earth’s surface is what causes fair-skinned people to get sunburned.
out new stars. GALEX’s UV surveys will help scientists
measure not only star formation rates, but many othercharacteristics of galaxies, such as luminosity (brightness),
shape, gas content, how galaxies cluster together, and how
such properties change over cosmic time.
We may not be able to actually place ourselves into
the past, but remember: Space is time and time is space.
So to look far back in time, all you need is a good telescope!
Now, test your galactic IQ by solving one or both of these word puzzles. But don’t cheat! If you do both
puzzles, do the crossword first.
The starship Cosmographer receives a distress signal. Zorp, the communication officer, announces it is coming from an ally’s damaged ship four light years away. How might Zorp know the distance to the source of the signal? Should the crew just drop everything and rush to the aid of the ship in distress? Why or why not? What would have to be different from our current understanding of science for the Cosmographer to get to the damaged ship on time to save its crew?
EXPLORING THE GALAXIES
Across
1 All there is3 Nearby star
6 Common to human, octopus, and some galaxies
7 Viewer into the past
9 The blanket above us
12 Our galactic home
16 Another eye in the sky
17 Light gets under your skin
19 The youngest and the _____21 Like air out in space
24 Amoeba-like galaxy
26 Pinwheel galaxy
29 From where we stand
30 Our closest celestial family
33 How much it shines
35 Much stranger than that of Alice’s rabbit
36 More than blue
2 True nothingness
4 Space agency of the U.S.
5 Make longer
8 What started the whole thing
10 Opposite of contracting
11 A red star is this
13 A blue star is this
14 Raw material for new stars
15 Light made longer
18 Change over time
20 Age of the universe, times about 12 years
22 Great balls of fire
23 Star student
25 Egg-shaped galaxy
27 The farthest artifact
28 Surveying the galaxies
31 Speediest traveler
32 Pulse of energy
34 Lots made where stars are born, abbreviation
Originally published in The Technology Teacher, May/June 2003, by the International Technology Education Association
The words in the list on the left are hidden in the jumble of letters. Words may be
frontwards, backwards, upside-down, or diagonal. When you find a word, draw a
box around it and cross it off the list.
The words in the list on the left are hidden in the jumble of letters. Words may be
frontwards, backwards, upside-down, or diagonal. When you find a word, draw a
box around it and cross it off the list.
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