1. TEKS 8.8C Explore how different wavelengths of the electromagnetic spectrum such as light and radio
waves are used to gain information about distances and properties of components in the universe.
How Do Astronomers Learn About
the Universe?
• The stars and other objects in space are very far from Earth.
Only a few solar system objects are close enough to be
explored with probes.
• Astronomers rely on electromagnetic waves to gain information
about the universe.
• Electromagnetic waves consist of electric and magnetic
vibrations that travel through space.
(contd.)

2. TEKS 8.8C Explore how different wavelengths of the electromagnetic spectrum such as light and radio
waves are used to gain information about distances and properties of components in the universe.
• The electromagnetic spectrum consists of all the wavelengths
of electromagnetic radiation.
• The electromagnetic spectrum includes light, radio waves,
X-rays, gamma rays, and ultraviolet and infrared radiation.

3. TEKS 8.8C Explore how different wavelengths of the electromagnetic spectrum such as light and radio
waves are used to gain information about distances and properties of components in the universe.
What are Telescopes?
• Telescopes are instruments that collect electromagnetic
radiation and bring it into focus.
• Optical telescopes collect visible light.
• Radio telescopes detect radio waves.
• The Spitzer Space Telescope captures images in the infrared
portion of the spectrum.
• The Chandra X-ray Observatory captures images in the X-ray
portion of the spectrum.
1. Compare How are all telescopes the same?

4. TEKS 8.8C Explore how different wavelengths of the electromagnetic spectrum such as light and radio
waves are used to gain information about distances and properties of components in the universe.
What Information Can Radio
Waves Provide?
• Radio waves have provided scientists with valuable information
about the universe.
• Regular pulses of radio waves from space led astronomers to
discover spinning neutron stars called pulsars.
• After astronomers detected faint radiation on their radio
telescopes coming from all directions, they hypothesized that
this cosmic background radiation is the leftover thermal energy
from the big bang.

5. TEKS 8.8C Explore how different wavelengths of the electromagnetic spectrum such as light and radio
waves are used to gain information about distances and properties of components in the universe.
What Information Can Visible
Light Provide?
• Because of the vast distances in the universe, astronomers use
the light year to measure distances in space. A light year is the
distance light travels in a year.
• Astronomers have learned that all known stars, including the
sun, have a nearly identical chemical composition. An
astronomer analyzing a star or another component of the
universe often starts by studying the object’s spectrum.
2. Explain How are astronomers able to determine the chemical composition of
stars?

6. TEKS 8.8C Explore how different wavelengths of the electromagnetic spectrum such as light and radio
waves are used to gain information about distances and properties of components in the universe.
What Information Can
X-rays Provide?
• A black hole is an object with gravity so strong that nothing, not
even light, can escape.
• No light, radio waves, or any other form of radiation can escape
a black hole, so it is not possible to detect black holes directly.
• Astronomers detect X-rays coming from hot gas located near a
black hole and infer that a black hole is present.

7. TEKS 8.8C Explore how different wavelengths of the electromagnetic spectrum such as light and radio
waves are used to gain information about distances and properties of components in the universe.
What Other Information Might
Electromagnetic Waves Provide?
• By studying the shift of color of the light from stars, astronomers
discovered a planet revolving around an ordinary star like our
sun.
• Since this first discovery, more than 300 planets have been
discovered around other stars.
• The discovery of new planets brings up the question of whether
there is life in other solar systems.
3. Make a Hypothesis How might electromagnetic waves help scientists
discover life on other planets?