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What Does the Infrared
Have to Do With Space?
Look at the difference between
visible and infrared light!
What is Infrared Light?
• Infrared light is a form of electromagnetic
radiation, one that is invisible to our eyes.
• Infrared light is what we commonly think of as
“heat” radiation. Heat is the kinetic energy
stored in the motion of atoms and molecules.
• Infrared light is emitted by anything in the
universe with a temperature (above absolute
zero).
• Objects below 1,000 degrees C radiate mostly
in the infrared.
Infrared and Temperature
Dr. Michelle Thaller (Senior Scientist, California
Institute of Technology) seen with an infrared
camera (after playing with an ice cube). Things
can look quite different in infrared light.
Properties of Infrared Light
• Infrared light can
pass through many
things that block
visible light, like
smoke and dust (and
most plastics).
Michelle Inside of Black Plastic Bag
Fireman Inside of Smoke-filled Room
Properties of Infrared Light
• Infrared Light is also
blocked by things
that let visible light
through (like our
atmosphere!)
A Piece of Glass Completely
Blocks Infrared Light
• Because of its
relatively long
wavelength,
Infrared Light
can travel more
readily through
Interstellar Dust
(similar in size to
smoke) than
visible light.
What a difference Temperature
Makes (Blackbody Radiation)
Infrared Astronomy Explores:
• Objects in space that are too cool to radiate visible light
– Planets, interstellar dust clouds, Brown Dwarfs, protoplanetary disks
• Objects and processes that are obscured by dust
– Star and planet formation, active galactic nuclei (black
holes)
• The Very Distant Universe
– Radiation from the early universe has been red-shifted
into the infrared
– Young galaxies appear to be shrouded in dust
• Interesting Chemistry
– Spectral lines of water, CO2, organic molecules in
infrared region
The Heritage of Infrared
Astronomy
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Infrared discovered in 1800 by William Herschel
First infrared telescopes built in 1960’s.
Kuiper Airborne Observatory in 1970’s.
IRAS (Infrared Astronomical Satellite) in 1983.
ISO (Infrared Space Observatory) flown by ESA
in 1995.
• SIRTF (Space Infrared Telescope Facility)
launched in 2003.
BROWN DWARFS
Failed Stars of the Universe
The mass of a brown
dwarf is no more than
eight percent of the
Sun’s mass, and many
are not much bigger
than Jupiter.
Infrared Spectra of a Red Dwarf and a Brown Dwarf
The major difference
in the two is the high
level of methane
found only in brown
dwarfs.
Extrasolar Planet and Planetary
Disk Detection
This is an example
of a warm disk of
material around a
star where planets
may be born.
Near Infrared image of Beta Pictoris
These warm
dust disks
around stars
give clues to
the presence of
planets
Young stars, mostly unseen, are
hidden in these clouds.
Orion Nebula
Visible Light
What a difference the infrared view
makes!
Orion Nebula
Infrared view
Active Galactic Nuclei
(Giant Black Holes)
What powers the most
luminous galaxies in the
universe? Perhaps giant
black holes fed by turbulent
galaxy mergers. Whatever it
is lies hidden behind dust.
And Closer to Home…
The Center of the Milky Way in
visible (left) and infrared (right)
shows signs of having a similar
massive black hole.
Seeing to the end of the Universe
The farthest objects in the universe
are heavily red-shifted, in some
cases completely out of the visible
range. Infrared can probe deeper,
exploring the first proto-galaxies as
much as 14 billion light years away.
Space Infrared Telescope
Facility
SIRTF launched on Sunday,
August 24, 2003 at 11:35:39
p.m. MDT
Which waves of light cannot be
observed from Earth?