ASP Knowledge 4 — Questions and Answers
Question 1: What is the term for the point in a planet's orbit when it is closest to the Sun?
- Aphelion
- Perihelion (Correct answer)
- Apogee
- Perigee
Correct answer: Perihelion
Perihelion is the orbital point closest to the Sun; Earth reaches perihelion in early January each year.
Question 2: Which spectral class of stars is hottest and appears bluish-white?
- K
- G
- M
- O (Correct answer)
Correct answer: O
O-type stars are the hottest stars (surface temperatures above 30,000 K) and appear blue-white in color.
Question 3: What are the dark areas on the Sun's surface caused by concentrated magnetic field regions called?
- Solar flares
- Prominences
- Sunspots (Correct answer)
- Granules
Correct answer: Sunspots
Sunspots are temporarily cooler, darker areas on the photosphere where strong magnetic fields inhibit convection.
Question 4: What is the name of the force that keeps planets in orbit around the Sun?
- Electromagnetic force
- Nuclear force
- Dark energy
- Gravity (Correct answer)
Correct answer: Gravity
Gravity, described by Newton's law of universal gravitation and refined by Einstein's general relativity, keeps planets in their orbits.
Question 5: The Milky Way galaxy is classified as what type of galaxy?
- Elliptical
- Irregular
- Barred spiral (Correct answer)
- Lenticular
Correct answer: Barred spiral
The Milky Way is a barred spiral galaxy with a central bar-shaped structure of stars from which spiral arms extend.
Question 6: What is the cosmic microwave background (CMB) radiation?
- Radiation from active galactic nuclei
- Thermal radiation left over from the Big Bang (Correct answer)
- X-rays emitted by neutron stars
- Gamma-rays from supernovae
Correct answer: Thermal radiation left over from the Big Bang
The CMB is the thermal radiation remnant from the early universe, approximately 380,000 years after the Big Bang, now cooled to about 2.7 K.
Question 7: What is the Chandrasekhar limit?
- The maximum distance light can travel in the universe
- The maximum mass a white dwarf can have before collapsing (Correct answer)
- The minimum mass a star needs to fuse hydrogen
- The maximum size of a neutron star
Correct answer: The maximum mass a white dwarf can have before collapsing
The Chandrasekhar limit (~1.4 solar masses) is the maximum mass a white dwarf can sustain before electron degeneracy pressure fails and it collapses.
ASP Knowledge 4
What is the term for the point in a planet's orbit when it is closest to the Sun?