Science and Technology › Space
Astronomy and cosmology Astronomy and cosmology: telescopes and observatories, stars, black holes and neutron stars, exoplanets, dark matter and dark energy, the Sun's cycle and space weather, eclipses, comets and asteroids. Prelims has asked about Cepheids, nebulae and pulsars, and about solar flares.
UPSC has asked
Prelims 2025: solar flares and coronal mass ejections striking the outer atmospherePrelims 2023: Cepheids, nebulae and pulsarsPrelims 2022: effects of a major solar storm on the EarthNo subject here changed from 1 to 15 July 2026. Show all
corona The Sun's outermost atmosphere, extending millions of kilometres into space and far hotter than the visible surface below it. coronagraph An instrument that blocks a bright disc so that what lies close beside it can be seen: the Sun's corona without an eclipse, or a planet beside another star. coronal mass ejection A huge burst of magnetised plasma thrown out of the corona into space, which can reach the Earth and disturb its magnetic field. path of totality The narrow strip on the Earth's surface from which the Moon is seen covering the Sun completely. Red supergiant A massive star late in its life that has swollen to an enormous size and cooled to a red colour. Very Large Telescope The European Southern Observatory's array of four 8.2 metre telescopes in the Atacama Desert of Chile. Lagrange Point 2 A point about 1.5 million km beyond the Earth, directly away from the Sun, where a spacecraft circles the Sun in step with it. dark matter Unseen matter that neither emits nor absorbs light and is detected only through its gravitational pull. Hawking radiation Radiation black holes are predicted to emit as they lose mass; smaller ones evaporate faster. millisecond pulsar A neutron star, the collapsed core of a dead star, spinning hundreds of times a second and sweeping a beam of radiation past Earth. Also filed elsewhere Space weather forecasting from Aditya-L1 · on Moon, Sun and planetary missions A solar flare gives no useful warning once it has erupted, because its radiation crosses to Earth in about eight minutes.
The Hanle Dark Sky Reserve · on Chemicals, noise, light and soil pollution Ladakh's administration notified the Hanle Dark Sky Reserve (HDSR) in December 2022, India's first and still its only one.
Previous theme in this edition Human spaceflight and space stations Next theme in this edition Space policy, private sector and governance Practise previous year questions from this area Last updated 19 Sep 2026.
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