Guide to Major Telescopes

Editor: Courtney Dressing, Josh Fuchs

One of the most exciting aspects of being an astronomer is the ability to use fantastic telescopes both on the ground and in space. This guide describes some of the current and future telescopes that you’re likely to hear about at colloquia and conferences. This list is not exhaustive, but should help you recognize acronyms and learn a little bit more about how astronomers use them.

Atacama Large Millimeter Array (ALMA)

ALMA is a radio and millimeter observatory located in Chile that began operations in 2011. ALMA allows astronomers to image young planets embedded in disks around nearby stars, observe flowing molecular gas, and measure abundances of elements in galaxies.

The James Webb Space Telescope (JWST)

JWST is an exciting space-based infrared observatory that promises to acquire a wealth of photometric and spectroscopic information. For studies of the ISM, JWST will be particularly useful for mapping the distribution of dust and for observing obscured systems such as young stellar objects and circumstellar disks (see Gardner et al. 2006).

Thirty Meter Telescope (TMT)

TMT will conduct near-UV, optical, and near-infrared observations of young stellar objects, protoplanetary disks, and hot, young Jovian planets. The large primary mirror of the telescope and the adaptive optics system will allow TMT to produce high-resolution images of star and planet formation that include small-scale details that are unobservable with current telescopes.

Giant Magellan Telescope (GMT)

GMT has the same strong science case as TMT, but will be a ~25m telescope in the southern hemisphere. The main differences between GMT and TMT are shown in the table below.

Comparison of GMT and TMT

Comparison of GMT and TMT. GMT information from TMT information from


NASA’s Kepler Spacecraft began operations in 2009. The goal of the Kepler mission was to stare at patch of sky in Cygnus for 3 straight years to search for exoplanets. Kepler helped discover its share of exoplanets, while also providing insight into stellar pulsations and some very strange systems. In 2013, one of the reaction wheels failed and the Kepler mission was repurposed as the K2 mission. K2 pointed at regions of sky near the ecliptic, changing fields every 3 months. The K2 mission has had great success, continuing to find more exoplanets and other interesting stellar phenomena.

Chandra X-ray Telescope

Chandra is an X-ray observatory that has operated since 1999. Chandra has contributed to our understanding of extremely bright X-ray sources, figuring out how gas is exchanged between galaxies, watching black holes eat, and helping characterize the densest galaxies.

Spitzer Space Telescope

Spitzer is an infra-red space telescope launched by NASA in 2003. Spitzer was originally able to observe at wavelengths between 3.6 μm and 160 μm between two imaging instruments and one spectrograph. In 2009, Spitzer ran out of the liquid helium required to observe at these wavelengths. Since 2009, the Spitzer Warm Mission has used one camera to image at 3.6 μm and 4.5 μm.  Spitzer has contributed to our understanding of microlensing events, close and far away exoplanets,  amongst other discoveries.

Keck Observatory

The Keck Observatory is two 10 meter telescopes located on Mauna Kea, Hawai’i. They have been operating since 1993 (Keck I) and 1996 (Keck II). The Keck telescopes are two of the largest optical and infrared telescopes in the world. Scientifically, Keck observations have lead to a better understanding of cosmic reionization, the first galaxies, and characterizing exoplanetsexoplanet atmospheres. You can read about Astrobiter Lauren Weiss’ chance to observe the ‘supernova of a generation’ with Keck here.

Gemini Observatory

The Gemini Observatory is another set of two telescopes. Gemini North is located on Mauna Kea, Hawai’i. Gemini South is located on Cerro Pachon, Chile. They started operating in 1999 and 2000, respectively. Both telescopes have primary mirrors that are 8.1 meters in diameter. Astronomers have used the Gemini telescopes to study pulsating white dwarfs, the interactions of galaxies, and exoplanet atmospheres. You can read about Astrobiter Caroline Morley’s experience observing with Keck here.


List to add: VLT, South Pole Telescope