ASTR Midterm II

• All types of light are not radioactive in nature.
• Ultraviolet light is responsible for causing sunburns/skin cancer on Earth.
• The main factor behind the specific color of visible light is the wavelength of the light.
• Radio waves can completely pass through Earth's atmosphere and reach the surface.
• The peak wavelength of blackbody radiation emitted by the Sun is in visible/optical light.
• The peak wavelength of the visible light radiation emitted by the Sun is green.
• The Doppler effect assists astronomers in determining the motion of stars and galaxies by observing the shift in the spectrum of emitted light.
• In astronomy, the velocity of the celestial object relative to the observer affects the magnitude of the Doppler Shift of objects.
• Betelgeuse is red because its surface is cooler than the surface of the Sun.
• If two lit up objects are moving in the same direction at different speeds, the faster of the two will emit light that is measured at/observed by (the slower body) to be redshifted (relative to rest).
• If Star X is moving very quickly away from Earth and Star Y is moving very slowly towards Earth, Star X will show a large redshift and Star Y will show a small blueshift.
• A star appearing red does not guarantee that it is moving away from Earth.
• When viewing an absorption spectrum, the spectral dark lines/gaps represent light that was absorbed by a cool, low-density cloud along the way.
• When an astronomer observing a glowing cloud of gas in visible light uses an instrument containing a diffraction grating with thousands of grooves on its surface, it will spread out the light reaching the telescope (from the gas) into a spectrum.
• All the planets (without exception) revolve around the Sun in the same direction.
• Carbon dioxide makes up most of the atmosphere of Mars and Venus (but thin vs. thick).
• The planet that orbits "on its side" is Uranus.
• One piece of evidence that can help astronomers sort out how the planets in our solar system formed is finding circumstellar disks of material around nearby stars.
• The solar system formed by the collapse of a giant interstellar cloud of gas and dust, caused by gravity.
• A Red Giant is not a stage in the formation/origin of the Solar System.
• We believe the maria on the Earth's Moon are ancient impact craters in which lava beds welled up from inside the Moon due to thinner local crust.
• Mars's atmosphere has an overall reddish color when we see its surface from afar because its surface contains a lot of iron oxide, the same chemistry that makes rusting metals look reddish.
• Venus has a thick layer of clouds containing sulfuric acid droplets and a thick atmosphere of carbon dioxide which acts like a greenhouse effect, keeping it hot.
• We estimate the ages of planetary features by counting the craters visible on the surface and comparing crater counts to other worlds.
• Mars rovers (such as Opportunity and Curiosity) have identified evidence that their landing sites were once underwater because they found rock formations that show the area was underwater and minerals that only form in water.
• Centripetal force prevents objects from moving in a straight line indefinitely, keeps celestial bodies/satellites in orbit around their host body, prevents us from being flung outward when in a circle. By equating it to the gravitational force, we find an inverse relation between orbital speed and radius.
• The outer planets being subjected to enormous atmospheric pressures due to how massive they are does not contribute to why they spin faster than the inner planets.
• For a planet to have an active magnetosphere:

  There must be a mechanism of ongoing heat distribution (convection) in said planet interior.

  The planet must be rotating rapidly on its axis.

  A portion of the planet's interior must be molten and made of material that can conduct electricity.
• Io is the most volcanic place in the solar system due to Jupiter's massive tidal effect.
• Uranus has no known internal heat source, whereas Neptune does like the other two giant planets.
• Uranus and Neptune both have methane haze and clouds, but Neptune's atmosphere is tiny.
• The thicker atmospheres in giant planets help store and circulate heat from the Sun all over the planet.
• Giant planet satellites (e.g. Titan, Enceladus, Europa) have attracted so much recent attention from the astrobiology community:

  Plumes suggest the presence of abundant liquid water beneath their surface in subsurface oceans

  Titan has an abundant reservoir of organic molecules in liquid form thought to be important to early life formation on Earth
• The deep interior of giant planets has a much larger portion of lighter stuff like hydrogen and a variety of ices due to how giant planets formed at the distances they did from the Sun.
• Order of planets from nearest to furthest to Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• The Asteroid Belt is located between Mars and Jupiter.
• The Kuiper Belt extends from Neptune's orbit to where the known dwarf planets are.