1. What is the “cosmic neutrino background” (CνB)?
- A) A background of low-energy neutrinos left over from the Big Bang
- B) Neutrinos produced by supernovae throughout the Milky Way
- C) A flux of neutrinos generated by active galactic nuclei
- D) Cosmic rays deflected by intergalactic magnetic fields
Answer: ✅ :alphabet-white-a: A background of low-energy neutrinos left over from the Big Bang
Like the CMB, the CνB formed when neutrinos decoupled from matter roughly one second after the Big Bang, preserving information about the early thermal history of the universe.
2. What defines a “cold Jupiter” compared to a “hot Jupiter”?
- A) A gas giant with high albedo but close-in orbit
- B) A Jupiter-like planet orbiting far from its star beyond the snow line
- C) A gas giant with a molten metallic core
- D) A planet formed through direct gravitational collapse
Answer: ✅ :alphabet-white-b: A Jupiter-like planet orbiting far from its star beyond the snow line
Cold Jupiters likely form where ices condense (typically >~3 AU) and often remain there, whereas hot Jupiters are thought to migrate inward after formation.
3. In pulsar astronomy, what does a “glitch” refer to?
- A) A temporary radio silence caused by magnetospheric collapse
- B) A sudden spin-up in the pulsar’s rotation rate
- C) A numerical error in timing residuals
- D) A drop in spin frequency due to accretion torque reversal
Answer: ✅ :alphabet-white-b: A sudden spin-up in the pulsar’s rotation rate
Glitches likely arise from angular-momentum transfer between a neutron star’s superfluid interior and its crust, offering rare probes of ultra-dense matter.
4. Which observations first directly imaged an exoplanetary system around a Sun-like star?
- A) Hubble Space Telescope
- B) Kepler
- C) Gemini Planet Imager
- D) HR 8799 observations with the Keck and Gemini telescopes
Answer: ✅ :alphabet-white-d: HR 8799 observations with the Keck and Gemini telescopes
In 2008, astronomers captured multiple massive planets around HR 8799 — the first direct images of an exoplanetary system around a main-sequence star.
5. The “Great Attractor” refers to what phenomenon?
- A) A hypothesized supermassive black hole at the Milky Way’s center
- B) A gravitational anomaly pulling local galaxies toward a massive concentration of matter
- C) A dark energy overdensity accelerating cosmic expansion
- D) The barycenter of the Local Group
Answer: ✅ :alphabet-white-b: A gravitational anomaly pulling local galaxies toward a massive concentration of matter
Located toward the Centaurus–Hydra region and obscured by the Galactic plane, it helps explain peculiar velocities of nearby galaxies.