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National Aeronautics and Space Administration
National Aeronautics and Space Administration
Supplemental Educational Support Materials
for Special Feature: “A Horse of a Different Color”
Discussion questions
Q1:
Study the visible- and infrared-light images of the Horsehead Nebula.
Compare the features in each picture.
Answer:
The features seen in the visible-light image consist of a dark, cloudy region across
the bottom of the picture; a horsehead-shaped feature rising in the center; a bright
blue-green area at lower left; glowing reddish-pink gas just above the dark cloud; and
a large, bright star near the top. More stars also are visible in the image’s upper region
than in the dark, lower area.
The infrared image reveals a softly glowing structure with gas and dust swirling
around a rust-colored opaque region. The dark sky above the nebula is dotted with
many stars. Two recently formed stars are peeking out of the rusty cloud near the top
of the horse’s head. A blue glow silhouettes the top of the horse, a sign that Sigma
Orionis continues to rain down its high-energy light. Many background stars are
visible through the cloud of dust that is the Horsehead Nebula.
Q2:
Why do astronomers use many different parts of the electromagnetic
spectrum to view celestial objects?
Answer:
Astronomers choose to view celestial objects in different parts of the
electromagnetic spectrum to uncover as much information as possible about them.
Some parts of the spectrum provide information about the object that is not seen
in other parts of the spectrum. For example, astronomers study black holes using
gamma rays; regions of hot gas using X-rays; very hot stars using ultraviolet light;
cool stars and star-forming regions using infrared light; and the cold gas found
between stars with radio waves.
Educational Product
Educators & Students Grades 5–8
Continued …
Q3:
The electromagnetic spectrum is composed of many different types of light.
The following types of light are ordered from the lowest-energy waves to
those of the highest energy: radio, microwave, infrared, visible, ultraviolet,
X-ray, and gamma ray. If you could observe the Horsehead Nebula in any of
these types of light, which would you choose and why?
Answer:
A student’s answer will depend on which part of the electromagnetic spectrum
is chosen:
• Radio waves can be detected from celestial objects in any kind of weather.
Sunlight, clouds, and rain do not affect a radio telescope. Many astronomical
objects give off radio waves, which give the astronomer clues about the object’s
makeup, structure, and motion.
• Microwaves can be used by satellites to study Earth’s geological features, such
as sea ice or rivers. Astronomers uncovered clues to the beginning of the universe
when the cosmic microwave background radiation was discovered.
• Infrared light allows astronomers to peer into clouds of gas and dust to reveal
objects hidden inside.
• Visible light is the only portion of the spectrum that our eyes detect. It has
been used by astronomers since ancient times.
• Astronomers use ultraviolet light to study stars and galaxies. Massive, hot stars
give off lots of ultraviolet light, but smaller, cooler stars do not. Astronomers can
learn about the evolution of stars and galaxies by studying the ultraviolet light they
give off.
• Many objects in space give off X-rays. They include black holes, neutron stars,
supernova remnants, and the Sun.
• Gamma rays, the highest-energy waves, are given off by solar flares,
supernovae, neutron stars, black holes, and active galaxies.
Vocabulary words
Astronomer(s)
A scientist who studies the universe and the celestial bodies residing in it, including
their composition, history, location, and motion. Many of the scientists at the Space
Telescope Science Institute are astronomers. Astronomers from all over the world use
the Hubble Space Telescope.
Dense
Crowded closely together, compact, thick, or tightly packed. For example, sunlight
cannot shine through smoke that is dense.
Continued …
Emit
To give off, send forth, or discharge. For example, stars emit light.
Hubble Space Telescope
An orbiting telescope that collects light from celestial objects in visible, near-ultraviolet,
and near-infrared wavelengths. The telescope’s primary mirror is 2.4 m (8 ft.) wide. It
orbits Earth about every 96 minutes and is powered by sunlight collected with its two
solar arrays.
Light-year
The distance light will travel in a year — about 10 trillion kilometers or 6 trillion miles.
Nebula
A cloud of gas and dust located between stars and/or surrounding stars. Nebulae are
often places where stars form.
Opaque
Limiting the passage of light through an object. Glass, for example, is transparent, and
most clouds are opaque.
Transparent
Allowing light to pass through an object. Glass, for example, is transparent, and most
clouds are opaque.
Education Standards
McREL Content Knowledge — Online Edition Standards and Benchmarks
http://www2.mcrel.org/compendium/browse.asp
Language Arts
Standard 7. Uses skills and strategies to read a variety of informational texts.
Level II (Grade 3–5)
Reads a variety of informational texts (e.g., textbooks, biographical sketches,
letters, diaries, directions, procedures, magazines).
Level III (Grade 6–8)
Reads a variety of informational texts (e.g., electronic texts; textbooks;
biographical sketches; directions; essays; primary source historical documents,
including letters and diaries; print media, including editorials, news stories,
periodicals, and magazines; consumer, workplace, and public documents,
including catalogs, technical directions, procedures, and bus routes).
SEE MORE Hubble images and read more
Star Witness news stories at Amazing Space,
NASA’s award-winning educational website for
K–12 students and teachers.
amazing-space.stsci.edu
www.nasa.gov