History of Astronomy Flashcards

Who first proposed the 'hypothesis of the primeval atom'—what we now call the Big Bang theory—in 1927?

Answer: Georges Lemaître

Georges Lemaître, a Belgian Catholic priest and physicist, proposed in 1927 that the universe began from an extremely dense initial state he called the 'primeval atom,' which preceded Hubble's observational confirmation.

Cecilia Payne-Gaposchkin's landmark 1925 doctoral thesis revolutionized stellar astronomy by revealing that stars are primarily composed of which element?

Answer: Hydrogen

Cecilia Payne showed that stellar spectra indicate stars are overwhelmingly composed of hydrogen (~90% by number of atoms), overturning the prevailing assumption that stars had similar composition to Earth.

Charles Messier compiled his famous catalog of nebulae and star clusters in the 18th century. What was his original motivation for creating this list?

Answer: To avoid confusing these fuzzy objects with comets he was hunting

Messier was a comet hunter who kept encountering fixed fuzzy objects that could be confused with comets, so he cataloged them to avoid wasting time re-examining them; his catalog now lists 110 beautiful deep-sky objects.

Jocelyn Bell Burnell and Antony Hewish discovered pulsars in 1967. What were pulsars initially nicknamed upon discovery due to their mysterious, extremely regular radio pulses?

Answer: LGMs (Little Green Men)

The source was briefly nicknamed 'LGM-1' (Little Green Men) because the pulses were so regular that an extraterrestrial artificial origin seemed a real possibility before a natural explanation was found.

Vera Rubin provided key observational evidence for dark matter in the 1970s by studying the rotation curves of spiral galaxies. What did her measurements reveal?

Answer: Stars at the outer edges of galaxies orbit just as fast as inner stars, implying much more mass than visible

Rubin found that stars in the outer regions of galaxies orbit at roughly the same speed as inner stars (flat rotation curves), indicating there must be large amounts of unseen 'dark matter' extending beyond the visible disk.

The Soviet Union's Sputnik 1, launched on October 4, 1957, marked the start of the Space Age. What was its primary scientific contribution beyond being the first artificial satellite?

Answer: It transmitted radio signals that allowed study of the ionosphere

Sputnik 1 transmitted radio beeps at two frequencies that scientists used to study the ionosphere by analyzing signal propagation, while its orbital decay also provided data on upper atmospheric density.

The James Webb Space Telescope, launched in December 2021, observes primarily in which part of the electromagnetic spectrum, enabling it to see through dust clouds and observe the early universe?

Answer: Infrared

JWST observes from 0.6 to 28 micrometers (near- to mid-infrared), allowing it to detect redshifted light from the earliest galaxies, peer through dust where stars form, and study exoplanet atmospheres.