A telescope is a device used to observe distant objects. Originally, telescopes were optical instruments using lenses and mirrors to observe visible light. Today, the term "telescope" encompasses a broader range of instruments that can detect various forms of electromagnetic radiation beyond the visible spectrum. Some telescopes even utilize detectors beyond those used for electromagnetic radiation.
1932: Aluminized Mirrors Introduced
In 1932, a significant advancement in telescope technology occurred with the introduction of aluminized mirrors. This innovation addressed the problem of fast tarnishing in reflecting telescopes, which had previously relied on silver-coated glass mirrors.
1937: First Purpose-Built Radio Telescope Operational
The year 1937 marked a pivotal moment in astronomical observation with the commencement of operations for the first purpose-built radio telescope. This event expanded the horizons of astronomy beyond the visible spectrum.
1952: Hans Wolter Outlines X-ray Telescope Designs
In 1952, Hans Wolter proposed three innovative methods for constructing telescopes using ring-shaped "glancing" mirrors made from heavy metals. These designs revolutionized X-ray astronomy by enabling the reflection and focusing of X-rays.
2005: Astronomical Interferometers Achieve Earth-Sized Virtual Apertures
By 2005, astronomical interferometers, using multiple dishes to create a 'virtual' telescope, reached a milestone. Using space-based very-long-baseline interferometry (VLBI), such as the Japanese HALCA and VSOP satellites, arrays achieved virtual apertures several times larger than Earth, significantly increasing resolution for observing distant objects.
June 2008: Fermi Gamma-ray Space Telescope Launched
June 2008 saw the launch of the Fermi Gamma-ray Space Telescope, a significant development in our ability to observe the universe in gamma rays. The Earth's atmosphere is opaque to gamma rays, necessitating space-based telescopes like Fermi.
2012: Discovery Raises Possibility of Focusing Gamma-ray Telescopes
A groundbreaking discovery in 2012 revealed that the index of refraction for photons starts to increase again at energies exceeding 700 keV. This finding opened up new possibilities for developing gamma-ray telescopes capable of focusing these high-energy photons.
2012: NuSTAR X-ray Telescope Launched
The launch of the NuSTAR X-ray Telescope in 2012 marked a significant step in X-ray astronomy. The telescope, employing Wolter telescope design optics on a deployable mast, allowed scientists to study high-energy photons up to 79 keV.
December 25, 2021: James Webb Space Telescope Launched
On December 25, 2021, NASA launched the James Webb Space Telescope, a groundbreaking observatory designed to detect infrared light. The launch took place in Kourou, French Guiana, marking a new era in space exploration and infrared astronomy.