Major Telescopes and their Observations

Relevance:
Prelims: Science and Technology,
Mains: GS III- Awareness in the fields of IT, Space, Achievements of Indians in Science & Technology; Indigenization of Technology and Developing New Technology.

What is a Telescope?

• A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation (such as visible light). The word telescope now refers to a wide range of instruments detecting different regions of the electromagnetic spectrum and in some cases other types of detectors.

Gamma-ray

• Gamma-ray telescopes collect and measure individual, high energy gamma rays from astrophysical sources. These are absorbed by the atmosphere, requiring that observations are done by high-altitude balloons or space missions.
• Gamma rays can be generated by supernovae, neutron stars, pulsars and black holes. Gamma-ray bursts, with extremely high energies, have also been detected but have yet to be identified.

X-ray telescopes

• X-ray telescopes measure high-energy photons called X-rays. These can not travel a long distance through the atmosphere, meaning that they can only be observed high in the atmosphere or in space. Several types of astrophysical objects emit X-rays, from galaxy clusters, through black holes in active galactic nuclei to galactic objects such as supernova remnants, stars, and binary stars containing a white dwarf (cataclysmic variable stars), neutron star or a black hole (X-ray binaries).
• Some Solar System bodies emit X-rays, the most notable being the Moon, although most of the X-ray brightness of the Moon arises from reflected solar X-rays. A combination of many unresolved X-ray sources is thought to produce the observed X-ray background.

Ultraviolet Telescopes

• Ultraviolet telescopes make observations at ultraviolet wavelengths, i.e. between approximately 10 and 320 nm. Light at these wavelengths is absorbed by the Earth's atmosphere, so observations at these wavelengths must be performed from the upper atmosphere or from space. Objects emitting ultraviolet radiation include the Sun, other stars and galaxies.

Visible light

• The oldest form of astronomy, optical or visible-light astronomy, observes wavelengths of light from approximately 400 to 700 nm. Positioning an optical telescope in space eliminates the distortions and limitations that hamper that ground-based optical telescopes, providing higher resolution images.
• Optical telescopes are used to look at planets, stars, galaxies, planetary nebulae and protoplanetary disks, amongst many other things.
• Infrared light is of lower energy than visible light, hence is emitted by sources that are either cooler or moving away from the observer (in the present context: Earth) at high speed. As such, the following can be viewed in the infrared: cool stars (including brown dwarves), nebulae, and redshifted galaxies.

Microwave Telescopes 

• Microwave space telescopes have primarily been used to measure cosmological parameters from the Cosmic Microwave Background. They also measure synchrotron radiation, free-free emission and spinning dust from our Galaxy, as well as extragalactic compact sources and galaxy clusters through the Sunyaev-Zel'dovich effect.

Radio Telescopes 

• As the atmosphere is transparent for radio waves, radio telescopes in space are of most use for Very Long Baseline Interferometry; doing simultaneous observations of a source with both a satellite and a ground-based telescope and by correlating their signals to simulate a radio telescope the size of the separation between the two telescopes. Observations can be of supernova remnants, masers, gravitational lenses, starburst galaxies, and many other things.

Square Kilometre Array- world’s largest radio telescope

• The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, with eventually over a square kilometre (one million square metres) of collecting area.
• The scale of the SKA represents a huge leap forward in both engineering and research & development towards building and delivering a unique instrument, with the detailed design and preparation now well underway. 

SKAO

• It is a new intergovernmental organisation dedicated to radio astronomy and is headquartered in the UK.
• At the moment, organisations from ten countries are a part of the SKAO.
• These include Australia, Canada, China, India, Italy, New Zealand, South Africa, Sweden, the Netherlands and the UK.

Significance of SKA telescope

• The telescope, proposed to be the largest radio telescope in the world, will be located in Africa and Australia whose operation, maintenance and construction will be overseen by SKAO.
• Some of the questions that scientists hope to address using this telescope include the beginning of the universe, how and when the first stars were born and the life-cycle of a galaxy.
• It would explore the possibility of detecting technologically-active civilizations elsewhere in our galaxy and understanding where gravitational waves come from.
• As per NASA, the telescope will accomplish its scientific goals by measuring neutral hydrogen over cosmic time, accurately timing the signals from pulsars in the Milky Way.

• From their locations on mountains in Hawai‘i and Chile, Gemini Observatory’s telescopes can collectively access the entire sky.
• The Gemini Observatory is a multi-national partnership that is comprised of two identical 8.1-meter (26.58 feet) telescopes – one on Hawaii's Mauna Kea and another on central Chile's Cerro Pachón.

Partner Countries

• The international partners include the United States, Canada, Chile, Australia, Brazil and Argentina.
• Astronomers in each country are allotted observing time in proportion to their country's contribution. The Gemini telescopes are the largest publicly funded optical/infrared telescopes available for astronomers in each of the partner countries.
• Gemini's advanced technology and superb optical and infrared capabilities allow it to probe areas of our universe with more clarity than has ever been possible.
• The Gemini Observatory's primary mission is to serve the general astronomical communities in all of the participant countries

Observations:

• The Gemini was one of the telescopes that observed the turn-on of a nuclear transient, along with the Swift space telescope and the Hiltner telescope (MDM observatory).

• Chandra is the world’s most powerful X-ray telescope. Chandra, named for Indian-American physicist Subrahmanyan Chandrasekhar.
• It examines the X-rays emitted by some of the universe’s strangest objects, including quasars, immense clouds of gas and dust and particles sucked into black holes.
• X-rays are produced when the matter is heated to millions of degrees. The hottest and most energetic areas are shown in purple
• Chandra X-ray Observatory observed light from exploded stars, million-degree gas, and material colliding around black holes and neutron stars.

• The red colours show infrared light, as seen by the Spitzer Space Telescope. These areas show the heat emitted by star-forming dusty lanes in the galaxy.
• Spitzer telescope gathers the infrared radiation emanating from cosmic objects, including faraway galaxies, black holes and even comets in our own solar system.
• Spitzer was the first telescope to see light from an exoplanet.

• Hubble, the observatory, was the first major optical telescope to be placed in space
• The yellow component is visible light, observed by the Hubble Space Telescope.
• Most of this light comes from stars, and they trace the same spiral structure as the dust lanes revealed in infrared.
• Hubble has shed light on the scale of the universe, the life cycle of stars, black holes, and the formation of the first galaxies.
• Hubble takes sharp pictures of objects in the sky such as planets, stars and galaxies. Hubble has made more than one million observations.
• Hubble has helped scientists understand how planets and galaxies form. An image called “Hubble Ultra Deep Field” shows the farthest galaxies ever seen.
• Hubble has detected black holes, which suck in everything around them, including light.
• The telescope has played a key role in the discovery of dark energy, a mysterious force that causes the universe to expand faster and faster as time goes on.
• And it has revealed details of gamma-ray bursts — powerful explosions of energy that occur when massive stars collapse.

• Herschel will be the largest, most powerful infrared telescope, looking at the far-infrared to sub-millimetre wavelengths of light generated by some of the coldest objects in space.
• Herschel is designed to look for water, both in nearby comets and faraway dust clouds, and will also peer into the womb of star formation.
• Like its predecessor Spitzer, Herschel will also take a peek at a few exoplanets.

• It is designed to observe potentially habitable exoplanets around sun-like stars. While looking for “biosignatures” like water and methane, which may indicate the presence of life on another planet, HabEx would also become the first telescope to directly image an Earth-like exoplanet.

• It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own Solar System. Webb is an international collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA).

• Herschel’s launch partner, the Planck Observatory, will be concentrating on the microwave light of the universe. Planck will be looking at the remnants of the first light to shine freely in the universe.
• Planck will also probe the mysteries of dark matter and dark energy and map the magnetic field of the Milky Way in 3-D.

• Kepler is NASA’s new planet-hunting telescope that will be specifically searching for other Earth-like planets in the galaxy.
• Kepler will be looking for characteristic variations in the light from a pre-selected target group of 100,000 stars. Dips in the light from the stars can indicate a planet passing in front of the star.

• Gamma rays can reveal some of the most energetic and mysterious events in the universe, including dark matter, black holes and spinning pulsars.
• Not long after arriving in orbit, it took an all-sky map that shows gamma rays from numerous sources, including our own sun.

• ARIES telescope is a joint collaboration between Indian, Russian, and Belgian scientists.
• The telescope is located at Devasthal, Nainital at a height of 2,500 metres
• The high-end technology incorporated in the telescope enables it to be operated with the help of remote control from anywhere in the world
• The telescope will be used in the study and exploration of planets, starts, magnetic field and astronomical debris
• The scientists will also help in the research of the structures of stars and magnetic field structures of stars.

• India’s first dedicated Astronomy satellite, AstroSat, completed its first year of successful operation on Sept 28, 2016.
• NASA’s Hubble Telescope provides data on the visible range while the Chandra observatory is limited to X-rays. In contrast, Astrosat would be a multi-wavelength space telescope
• ASTROSAT covers all ranges of wavelengths unlike any other space telescope
• To avoid repairing process as faced by HUBBLE, ASTROSAT has been launched with the life-time of five years only.

Scientific Objectives of ASTROSAT:

• To understand the high energy process in binary star systems containing neutrons star and black holes.
• To estimate the magnetic field of neutron stars.
• To study the star birth regions and high energy processes in star systems lying beyond our galaxy.
• To detect new briefly bright X-ray sources in the sky.
• To perform a limited deep field survey of the universe in the ultraviolet region.