Do you want to know about Spitzer Space Telescope?
While the Hubble takes images catching ultraviolet radiations (UV) of the objects, Spitzer captures infrared (IR) wavelengths between 3 and 180 microns. By the way, a micron is described as one-millionth of a meter!
But then how does that make a difference to us?
Human eyes can detect light in the range of 400-700 nanometers only, and so is the case with Hubble that it cannot detect longer wavelength radiations such as IR.
Spitzer has revealed many scintillating facts about celestial objects that Hubble has failed to come through even though Hubble is much powerful to see in the deep sky.
Do you know that objects colder than stars release infrared lights? To say, all “warm” objects emit infrared energy.
But what do we mean by the term warm here?
Warm means the temperature of the object is above absolute zero or over -273 degrees Celsius. This also means that practically all objects release infrared lights.
The advantage with Spitzer telescopes is that it is much easier to view through the far off dust and find planets around stars in our galaxy.
After all, we all are interested to know if life exists in any other planets outside our solar system!
Nonetheless, the fact remains that IR radiations from celestial objects cannot be detected from Earth’s surface because it gets absorbed in the atmosphere. That is why Spitzer was placed into space to explore objects that cannot be detected by normal telescopes.
Unlike Hubble, Spitzer does not orbit Earth but trails behind Earth. Spitzer has been set to move around Sun at a slower pace than Earth!
This also means that with the time Spitzer moves away and away from Earth. This helps scientists to safeguard Spitzer from the heat of Earth enabling it to detect deep-sky images effectively.
The Earth-trailing orbit means Spitzer receives less heat from Earth and remains cool as close as possible to absolute zero, which is extremely crucial for ultrafine images!
To detect weak infrared light coming from the deep-sky objects of the sky, Spitzer needs to remain cool! In other words, telescopes including all instruments need to remain as close as possible to absolute zero so as to protect it from infrared noise.
While all instruments are cooled cryogenically, Spitzer uses only 360 liters of liquid helium for this purpose!
Spitzer is not a large telescope at all; the diameter of Spitzer is barely 0.85 meters, and in that sense, it is a small telescope when compared with other large optical telescopes installed on this planet.
You may be surprised to note that the entire observatory weighs only 950 kilograms. As many as close to 300,000 detectors called the “eyes” of Spitzer scan deep-sky objects invariably.
Spitzer has three instruments at its disposal for scientific discoveries in space: an infrared spectrograph, an infrared camera equipped with a series of arrays, and an imaging photometer.
The infrared spectrograph is used for spectroscopy at mid-infrared wavelengths. No moving part is involved in designing this spectrograph.
The infrared camera takes images at near-to-mid infrared wavelengths.
The imaging photometer has been deployed for collecting spectroscopic data at far-infrared wavelengths. The main mirror is the only moving part for effective mapping of areas of deep-sky.
Brown Dwarfs are the objects that do not have sufficient mass to trigger fusion reaction in its core. In scientific language, they are failed stars and remain much cooler than yellow stars. Such brown dwarfs can be detected only through infrared emissions, and Spitzer is successful in finding Brown Dwarfs in the universe!
Many galaxies emit more radiation in infrared and therefore, cannot be detected by optical telescopes. Spitzer helps locate such galaxies in the deep-sky.
As you are aware, the universe has been expanding, and many faraway galaxies that are moving away from us cannot be detected in optical or ultraviolet light. Their detection is possible through only infrared light. In fact, such galaxies can provide us clue to the origin of the universe.
Many flattened discs not only move around stars but constitute the main source for planets to evolve in the future. While many of these discs have exhausted their gas, they are now the fertile ground for construction of planetary systems of the types as exist in our own solar system.
While Spitzer’s original mission was not to explore objects beyond our solar system, it has made some of the remarkable discoveries. Some of them can be described as per the below.
Since infrared light can penetrate gas and dust clouds much better than UV light, Spitzer has discovered “Rho Oph” clouds said to be the closest nebula yet almost 410 light years away from Earth in the Scorpios constellations where indications of star formation have been clearly noticed.
Spitzer has detected a very distant galaxy called COSMOS-AzTEC3 said to be almost 12 billion light-years away from Earth. This detection has given enormous data and insight into the formation of galaxies.
Spitzer detected Saturn’s largest ring system that remained invisible by all telescopes until Spitzer sensed it. The ring is almost 170 times wider and 20 times thicker than the diameter of Saturn!
Spitzer has identified at least two distant massive black holes at a distance of almost 13 billion light-years from our Earth.
Usually, optical telescopes find difficulty in detecting planets in deep-sky outside our solar system. But, Spitzer has successfully located planets that are as far as 13,000 light years from Earth.
Moreover, all optical telescopes have located planets outside of our solar systems indirectly either by the “wobble” or by the “transit technique,” but Spitzer has detected them directly by sensing infrared light coming from the planets.
In the wobble technique, inference of the planet is made by detecting the gravitational tug the planet exerts on its mother star, and by the transit technique planet’s presence is inferred when it comes in front of the star making it dimmer.
Spitzer is capable of finding out atmospheric conditions, winds, and temperatures on these planets with precision!
Spitzer has discovered at least three planets orbiting a dwarf star called TRAPPIST-1. All of these are Earth-like rocky planets. The TRAPPIST-1 star is located almost 40 light-years away from Earth in the constellation Aquarius. One of these planets is likely to have Earth-like life-supporting atmosphere.
Recently, in March 2017, Hubble Telescope has already reported the availability of water on some of these planets orbiting TRAPPIST-1 star.
Spitzer has given some remarkable insights about the planetary systems around stars in Milky Way opening new possibilities of further research. While its useful life was only five years, Spitzer is still operating after 16 years of its launch!
James Webb Space Telescope – much more powerful infrared telescope – will take over the job of Spitzer when launched somewhere in 2021 until then Spitzer will continue to provide useful details about the cosmos.