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#### Complete list of Terms and Definitions for AST and

Terms Definitions
Meteroid In orbit/space
Earth-Sun distance 1 AU
the sun "sunday" came from
speed wavelength (lambda) x frequency (nu)
energy .....is the mover of matter
filaments galaxies and galaxy clusters are arranged in a network of filaments (walls) surrounding large, empty regions of space known as voids.
new moon phase one of the moon
Hubbles Constant the SLOPE of Hubbles Law
Formula for surface gravity g = 6M/R2
Which of the following classes of stars is coolest? K9
closed universe For a high-density universe, the cosmic density parameter is greater than 1, the curvature of space is so great that it bends back on itself and the result is a closed universe. This is known as positive curvature and a closed universe is described as finite and unbounded (such as the surface of a sphere).
We can measure the temperatures of stars from a study of their: spectra
Meteorite a meteor that SURVIVES its passage through the atmosphere and HITS the ground
Velocity The measure of both direction and speed.
Barringer Crater in Arizona is an example of a meteorite impact True
crust of a planet) The low-density surface layer of a planet that has undergone differentiation.
Super Clusters Clusters of galaxies that come together (can be 100 million light years across)
How big is a disk, usually? 100 AU
On which of the following have we confirmed that life exists? Earth
Edwin Hubble In the 1920s, Edwin Hubble determined that the more distant the galaxy, the greater the recession velocity. This relationship is called Hubble's law and is stated: The rate at which a galaxy recedes from us is directly proportional to its distance from us. Figure 15.16 on page 415 shows plots of recessional velocity versus distance. The redshift resulting from this motion is called the cosmological redshift. Hubble's law is expressed in mathematical form as recession velocity = H0 x distance H0 is known as Hubble's constant - its value is uncertain but based on current measurements, its value is estimated to be between 50 and 80 km/s/Mpc. Most astronomers use 70 km/s/Mpc as the most reasonable value. Hubble's law can be used to determine distances to extremely remote galaxies. The galaxy's recession velocity can be determined by measuring the redshift of its spectral lines. The distance to the remote galaxy can be estimated by use of a plot such as in Figure 15.16. The recessional velocities of the most distant objects are more than 90% of the speed of light. This is perhaps one of the most difficult and complicated topics in astronomy and I feel that any attempt to discuss it in detail is far beyond the scope of this course.
Extragalactic SN many, but dimmer, more difficult to study.
Objects in the solar system? planets, stars, satellites, comets
Main-sequence phase surface radiates energy at same rate that core generates energy lasts about 10 billion years energy generated by nuclear fusion
Continuous Spectrum Appears as a constant rainbow of light
The oblateness of the jovian disks is caused by their rapid ________. rotation
Ring Galaxies the galaxies that resemble a RING around BRIGHT nucleus
greenhouse effect The process by which greenhouse gases in an atmosphere make a planet's surface temperature warmer than it would be in the absence of an atmosphere.
Galaxy Large group of stars, dust and gas held together by gravity; can be elliptical, spiral, or irregular. A group of stars held together by gravity.
Steady State theory A now-discredited theory that held that the universe had no beginning and looks about the same at all times.
Detected as Pulsars: Spinning once per second on averageRadio beam. (Caused by their strong magnetic field.)Slowest known pulsar is 5 &#10;seconds.
Harlow Shapley The structure of the Milky Way Galaxy was determined in the 1920s by Harlow Shapley. By studying variable stars in globular star clusters, he found that they have a spherical distribution in space and that the center of the sphere is far from the Sun (a globular cluster is a cluster of old stars and contains hundreds of thousands of stars. Shapley reasoned that the spherical region of globular clusters was centered on the galactic center (Figure 14.8, page 382). The most important aspect of Shapley's model was the fact that the solar system was at the outer edge of the galactic disk. The Milky Way Galaxy is 30 kpc (100,000 light years) in diameter. The galactic disk varies in thickness, but is about 300 pc (1000 light years) thick at the Sun's location. The galactic bulge is about 4 kpc (13,000 light years) thick. The Sun lies about 8 kpc (26,000 light years) from the galactic center.
Into which category do the majority of stars fall? main sequence
Before it arrived in orbit about Jupiter, the Galileo spacecraft flew past the asteroid Gaspra
north pole where are you if polaris is directly overhead?
a plane traveling at 10 km is in the troposhphere
white dwarf supernova a supernova that occurs when an accreting white dwarf reaches the white-dwarf limit, ignites runaway carbon fusion, and explodes like a bomb; often called a type la supernova
What are the major gaseous substances that make up Jupiter and Saturn? Hydrogen and helium.
solar cycle a 22-year cycle during which the sun's magnetic field reverses its polarity twice
Irregular galaxies. 1. Not elliptical- stars tend to orbit in a preferred direction.2. May have some messy disk 3. Dusty and gas rich.4. Young and blue stars.5. Not on Hubble Fork
Kepler's Law 1 Each planet's orbit around the Sun is an ellipse, with the Sun at one focus
On what day will the sun reach the highest position on the celestial sphere? Summer Solstice.
33 nanoseconds how long it takes my light to reach someone else
Property of Star - Speed tranverse velocity: how quickly the star moves across the sky tranverse velocity = distance/time
The concept of ___ ___ explains how a giant impact could lead to a mass extinction. Nuclear winter.
particle pair creation Using a photon we can create an electron and a antielectron(positron) *not sure if right*
What direction is blue and Redshift? Redshift - AWAYBlue - TOWARD
Large Impact Hypothesis origin of the moon. A LARGE body the size of mars smashed into the earth and effected DEBRIS into a disk around the earth where it formed out moon
The interstellar clouds called molecular clouds are _______. the cool clouds in which stars form
Property of Star - Mass what is the gravitational field of star? binary stars: P^2 (M1 + M2) = a^3
7. In a disk around a white dwarf, the gas that is closer to the white dwarf is moving (a) faster
Ranges in Stellar properties Di= 1/100 to 750 Do(Suns Diameter)M= 1/10 to 100MoL= 1/10,000 to 1,000,000 LoSurface temp= 2,500 to 50,000 K
Jupiter radiates back into space twice the energy it absorbs from the distant Sun. Where is this energy coming from, for the most part? the slow escape of gravitational energy left from its formation
In the proton-proton cycle, the helium atom and neutrino have less mass than the original hydrogen. What happens to the "lost" mass? its is converted to energy E=MC^2
Population I & II stars The stars that orbit within the disk of a spiral galaxy; sometimes called Population I. Stars that orbit within the spheroidal component of a galaxy; sometimes called Population II. Elliptical galaxies have only a spheroidal population (they lack a disk population), while spiral galaxies have spheroidal population stars in their bulges and halos.
How can black holes be detected? A massive object in a binary star system that emits large amounts of X- 100% radiation
The cities of Atlanta, GA and Boston, MA keep the same time because both cities: are in the same time zone.
If we know the average separation and period of revolution for a binary system, we can then determine the total mass of the system
If you were designing a pair of glasses to see animals at night, you would want the glasses to convert: Infared photons to optical (visible) photons.
Stars with less than 8 solar masses (98% of all stars): 1. Red Giants2. Horizontal Branch3. Asymptotic Giant Branch (AGB)4. Planetary nebula5. White dwarf:
Ch.20 Q#20: After measuring a galaxy's redshift, I used Hubble's law to estimate its distance. *explain if the statement is true or false and explain clearly* True as most astronomers use the law in reverse, first by getting the speed through redshift then calculate distance using Hubble law
What is the meaning of the solar constant? the amount of energy that earth receives per unit area and unit time
What is the first step in planet growth? What was this process called? Dust grains stick together to form dust bunnies; condensation and accretion
A sidereal day is _____ than a solar day because __________. shorter, the Earth moves with respect to the sun.
If the Kuiper Belt is 40 AU away, and the earth has a radius of 1.27 x 10^4 km, and one AU is equal to 1.5 x 10^13 cm, how many earths could you stack in between here and Pluto? 4.7 x 10^5 earths (remember significant figures)
Io exhibits a great deal of volcanic activity, indicating that its interior is very hot. What is Io's heat source thought to be? Io is subject to a strong and changing gravitational force from Jupiter that distorts its shape and heats it by internal friction.