Night And Day On An Alien World
The Hidden Universe of the Spitzer Space Telescope

Night And Day On An Alien World
The Hidden Universe of the Spitzer Space Telescope

The Spitzer Space Telescope (SST), formerly the Space Infrared Telescope Facility (SIRTF) is an infrared space observatory launched in 2003. It is the fourth and final of NASA's Great Observatories.

The US$800 million Spitzer was launched from Cape Canaveral Air Force Station, on a Delta II 7920H ELV rocket, Monday, 25th August 2003 at 13:35:39 UTC-5 (EDT).

It follows a rather unusual orbit, heliocentric instead of geocentric, trailing and drifting away from Earth's orbit at approximately 0.1 astronomical unit per year.

It's as clear as day and night ... but on an exotic alien world! Astronomers have for the first time measured the temperatures varying across the surface of an exoplanet -- a planet beyond our solar system.

The Spitzer Space Telescope (formerly the Space Infrared Telescope Facility, SIRTF) is an infrared space observatory launched in 2003.

It is the fourth and final of NASA's Great Observatories.

Planets orbiting other sun-like stars are notoriously difficult to observe; they're so distant that no telescope is yet powerful enough to photograph them directly.

Their feeble light is blurred into the glare of the stars they orbit. Nonetheless, since 1995 astronomers have discovered over 200 extrasolar planets by observing the effects they have on their parent stars.

These include gravitationally-induced wobbles, and even faint dimmings of the starlight when the planets pass in front.

The infrared eye of the Spitzer Space Telescope has already proven to be an exciting tool for learning more about these alien worlds.

In 2005, astronomers Drake Deming and Dave Charbineau announced the first detection of light from two extrasolar planets, seen as they went into eclipse behind their stars.

Now, astronomers Joe Harrington, of the University of Central Florida, and Brad Hanson, of UCLA, have taken this one step further.

They have actually measured differences between the day and night sides of such a world. This remarkable result marks the first time any kind of variation has been seen across the surface of a planet outside our solar system.

For now only imaginative artists can provide pictures of what they could look like. But until the day we can take real snapshots, astronomers will continue to find clever ways to explore this growing catalog of alien worlds.

The first images taken by SST were designed to show off the abilities of the telescope and showed a glowing stellar nursery; a big swirling, dusty galaxy; a disc of planet-forming debris; and organic material in the distant universe.

Since then, many monthly press releases have highlighted Spitzer's capabilities, as the NASA and ESA images do for the Hubble Space Telescope.

As one of its most noteworthy observations, in 2005, SST became the first telescope to directly capture the light from extrasolar planets, namely the "hot Jupiters" HD 209458b and TrES-1. (It did not resolve that light into actual images though.)

Spitzer is the only one of the Great Observatories not launched by the Space Shuttle, which had been originally intended. However after the 1986 Challenger disaster, the Centaur LH2/LOX upper stage, which would have been required to place it in its final orbit, was banned from Shuttle use.

The mission underwent a series of redesigns during the 1990s, primarily due to budget considerations. This resulted in a much smaller but still fully capable mission which could use the smaller Delta II expendable launch vehicle.

This was the first time extrasolar planets had actually been visually seen; earlier observations had been indirectly made by drawing conclusions from behaviors of the stars the planets were orbiting.

The telescope also discovered in April 2005 that Cohen-kuhi Tau/4 had a planetary disk that was vastly younger and contained less mass than previously theorized, leading to new understandings of how planets are formed.

While some time on the telescope is reserved for participating institutions and crucial projects, astronomers around the world also have the opportunity to submit proposals for observing time.

Important targets include forming stars (young stellar objects, or YSOs), planets, and other galaxies. Images are freely available for educational and journalistic purposes.

In 2004, it was reported that Spitzer had spotted a faintly glowing body that may be the youngest star ever seen.

The telescope was trained on a core of gas and dust known as L1014 which had previously appeared completely dark to ground-based observatories and to ISO (Infrared Space Observatory), a predecessor to Spitzer.

The advanced technology of Spitzer revealed a bright red hot spot in the middle of L1014. Scientists from the University of Texas at Austin, who discovered the object, believe the hot spot to be an example of early star development, with the young star collecting gas and dust from the cloud around it.

Early speculation about the hot spot was that it might have been the faint light of another core that lies 10 times further from Earth but along the same line of sight as L1014.

Follow-up observation from ground-based near-infrared observatories detected a faint fan-shaped glow in the same location as the object found by Spitzer. That glow is too feeble to have come from the more distant core, leading to the conclusion that the object is located within L1014.

In 2005, astronomers from the University of Wisconsin at Madison and Whitewater determined, on the basis of 400 hours of observation on the Spitzer Space Telescope, that the Milky Way Galaxy has a more substantial bar structure across its core than previously recognized.

Also in 2005, astronomers Alexander Kashlinsky and John Mather of NASA's Goddard Space Flight Center reported that one of Spitzer's earliest images may have captured the light of the first stars in the universe.

An image of a quasar in the Draco constellation, intended only to help calibrate the telescope, was found to contain an infrared glow after the light of known objects was removed. Kashlinsky and Mather are convinced that the numerous blobs in this glow are the light of stars that formed as early as 100 million years after the big bang, red shifted by cosmic expansion.

Revealing a Hidden Universe
The Spitzer Legacy Program

In March 2006, astronomers reported an 80-light-year-long nebula near the center of the Milky Way Galaxy, the Double Helix Nebula, which is, as the name implies, twisted into a double spiral shape.

This is thought to be evidence of massive magnetic fields generated by the gas disc orbiting the supermassive black hole at the galaxy's center, 300 light years from the nebula and 25,000 light years from Earth.

This nebula was discovered by the Spitzer Space Telescope, and published in the magazine Nature on March 16, 2006.

In May 2007, astronomers successfully mapped the atmospheric temperature of HD 189733 b, thus obtaining the first map of some kind of an extrasolar planet.

Since September 2006 the telescope participates in a series of surveys called the Gould Belt Survey, observing the Gould's Belt region in multiple wavelengths. The first set of observations by the Spitzer Space Telescope were completed from September 21, 2006 through September 27.

Resulting from these observations, the team of astronomers led by Dr. Robert Gutermuth, of the Harvard-Smithsonian Center for Astrophysics reported the discovery of Serpens South, a cluster of 50 young stars in the Serpens constellation.

In August 2009, the telescope found evidence of a high-speed collision between two burgeoning planets orbiting a young star. In October 2009, astronomers published findings of the "Phoebe ring" of Saturn, which was found with the telescope; the ring is a huge, tenuous disc of material extending from 128 to 207 times the radius of Saturn.