According to NASA, Spitzer was designed to study “the cold, the old and the dusty,” three things astronomers can observe particularly well in infrared light. It could sense infrared wavelengths from about 700 nanometers (microscopic) to about one millimeter (the size of a pinhead).
Different infrared wavelengths can reveal different features in the universe. For example, Spitzer could see things that were too cold to emit visible light, like exoplanets – the planets outside our solar system.
And speaking of “the old,” Spitzer was able to study some of the most distant galaxies ever detected. What is amazing is that the light from some of these distant galaxies had to travel for billions of years to reach us. This allowed scientists to observe these galaxies as they were long, long ago.
Actually, the Spitzer telescope, working with the Hubble telescope, identified the bright infant galaxy, named GN-z11, seen as it was 13.4 billion years in the past, just 400 million years after the Big Bang. GN-z11 is located in the direction of the constellation of Ursa Major. This was when the universe was less than 5 percent of its current age.
As for “The dusty,” Spitzer was up to the task in seeing through the dust that is prevalent throughout most galaxies. Using a technique called spectroscopy, Spitzer analyzed the chemical composition of dust to learn about the ingredients that form planets and stars.
Using spectroscopy, Spitzer detected an additional ring around the planet Saturn, made up of sparse dust particles that visible-light observatories can’t see. “It’s quite amazing when you lay out everything that Spitzer has done in its lifetime, from detecting asteroids in our solar system no larger than a stretch limousine to learning about some of the most distant galaxies we know of,” said Michael Werner, Spitzer’s project scientist.
On Thursday, NASA scientists will put Spitzer in “safe mode” and end the mission, according to Forbes. Even after ending the mission, the dead space telescope will continue in its current orbit as it slowly moves further away from Earth.
Let’s look at a few remarkable images sent back by Spitzer.
This image from NASA’s Spitzer Space Telescope shows the Cat’s Paw Nebula, so named for the large, round features that create the impression of a feline footprint. The nebula is a star-forming region in the Milky Way galaxy, located in the constellation Scorpius.
Spitzer’s observations have helped scientists to understand a lot about our solar system and the planet we live on, while also discovering other planets in the universe, in distant galaxies that may be habitable.
Spitzer’s observations led to the discovery of planets around the TRAPPIST-1 star. We now know that the system’s seven planets are all Earth-sized and terrestrial. Three appear to be habitable.
In closing this chapter on NASA’s Great Telescopes, we can look forward to the launch of the James Web Space Telescope, expected to be launched on March 30, 2021.