Show:
Light Properties
Telescopes & Scattering
Moon & Celestial Sphere
The Giants
Solar System
100
Light has a maximum possible speed. In what environment do we observe the maximum speed? What implications does this have when observing the night sky?
vacuum; when we look farther out, we are looking farther back in time
100
Scale Model: If the Sun (R=700,000 km) is scaled down to a basketball (R=25 cm), then how big would the Earth (R=7,000 km) be in the scale model?
R = 0.25 cm
100
How would total solar eclipses change if the Moon were half its current distance from Earth?
-wouldn't be able to see prominences, parts of the corona
100
What is retrograde motion? Compare and contrast Ptolemy and Copernicus’s explanation.
retrograde motion - west to east motion of planets; Ptolemy - used epicycles; Copernicus - heliocentric theory
100
Why is Mars red?
due to iron rust, NOT because it is thermally emitting at red wavelengths (it's not hot enough to do that)
200
Give three scenarios where Doppler shift is used to observe a particular system in astronomy. (three groups can answer)
1) planets rotating 2) spectroscopic binaries 3) detecting massive planets around other stars by measuring the Doppler wobble (periodic Doppler shift)
200
What is the primary purpose of telescopes? What mathematical relationship used to describe this?
-primary purpose is to collect light - Power proportional to Area
200
Uranus has a tilt of 90 degrees relative to the vertical axis. Describe what its seasons would be like.
-side of the planet not facing the sun never sees the sun until the season changes -> get much more extreme seasons -the orbit of Uranus is 84 years, so each season is 21 years long
200
What are Kepler’s three laws? (3 groups can answer)
1) Planetary orbits are ellipses 2) A line between the Sun and a planet sweeps out equal areas in equal times 3) The square of a planet's orbital period (P) is proportional to cube of its semimajor axis (R)
200
What is the hottest planet of the Solar System? What physical phenomenon makes it so hot?
Venus - Greenhouse effect
300
What are emission, absorption and continuous spectra? Give an example of each. (one group only)
emission - due to hot, tenuous, low pressure gas absorption - due to radiation from a hot, opaque object that passes through a cooler gas continuous - due to opaque body/gas, high pressure
300
Why do stars twinkle?
due to turbulence in the atmosphere and scattering of the light; stars twinkle more when closer to the horizon
300
What determines which stars are visible to you at night?
-horizon, see half of the celestial sphere from where you are on Earth (latitude)
300
What are Newton’s three laws? Give an example of each. (3 groups can answer)
1) If no forces act on a body, its speed and direction of motion stay constant. 2) F = ma 3) When two bodies interact, they exert equal and opposite forces on each other.
300
When can we see Mercury and Venus overhead at midnight?
Trick question! They're seen near sunset/sunrise because they are close to the sun.
400
If the spectrum of Star Jessica peaks at optical wavelengths and Star Jacob’s surface is twice as hot as Jessica’s surface, then in what part of the E&M spectrum does Star Jacob’s spectrum peak?
ultraviolet
400
List the advantages of using space-based telescopes over ground-based telescopes.
-no distortion by atmosphere: better resolution -darker sky -can capture wavelengths that Earth's atmosphere is opaque to
400
At what time on Earth is the Full Moon highest in the sky?
midnight
400
Newton: If the distance between two objects is doubled, how does the gravitational force between them change?
new force is 1/4 as strong
400
What planets in the Solar System have phases? Explain.
only the inner planets have phases; the outer planets do not have phases because they are always illuminated by the Sun
500
Star A has a temperature T, and radius R. Star B is twice as hot, but half as small as Star A. What is the luminosity of Star B compared to Star A?
Star B is 4 times more luminous than Star A.
500
You have an optical telescope that is 1 m in diameter that detects light at 5,000 Angstroms (1 Angstrom = 10^-8 m). If you wish to have a radio telescope with the same angular resolution, how big must its diameter be, if it detects radio signals at wavelength 5 m?
10^5 meters
500
When does the waning crescent rise and set?
rise: 3 AM; set: 3 PM
500
Two planets orbit a star that has the same mass as the Sun. Planet Alex orbits at a distance of 2 au while Planet Noelle orbits at a distance of 1 au. What is Planet Alex’s orbital period compared to Planet Noelle’s orbital period?
square root of 8
500
What causes Io (one of Jupiter's moons) to have volcanic eruptions?
tidal forces/friction that causes heating due to Io's proximity to Jupiter