Exam 1 Flashcards
If astronomers near Onion Nebula were able to see Earth clearly, what would they see? Why?
a tiny, pale blue dot against the backdrop of a much brighter, expansive nebula.
What kind of stars did Edwin Hubble use as standard candles to determine the distance galaxies?
Cepheid Stars
What do we call the earliest time in our Universe when it was very dense and very hot?
Big Bang
What proof exists of a young hot Universe?
Cosmic microwave background
Where are elements heavier than iron formed?
Stars, form during supernova explosions, death of massive stars
What percent of the solar nebula out of which the Solar System formed ended up in the Sun?
99.8%
Why are the planets that formed closer to the Sun composed primarily of silicates and iron compounds?
Too hot to hold the volatile gases that dominate the solar nebula
Why are the planets in the outer solar system so large?
Large size, large gravitational attraction (accelerates growth). They captured a large amount of hydrogen and other gases from the surrounding nebula with their enormous gravity
How do we explain the large exoplanets orbiting close to their stars that we have found?
migration
What features of the Solar System can be explained as a consequence of the Grand Tack Hypothesis
Small mars, asteroid belt, no super earth, no hot Jupiter
What features of the Solar System can be explained as a consequence of the Nice Model?
How the outer planets came to their present orbits, how the trojan asteroid in the outer solar system came into their orbital configurations. The migration of the outer planets caused instability among small bodies
What does the word planet mean?
Wanderer
How did the Ptolemaic Model explain retrograde motion?
Epicycles, circling the planet but circles the circle, used for 13 centuries
Who gave us the three laws of planetary motion?
Kepler
What is eccentricity?
It tells you how stretched out the orbit is
Who demonstrated that Kepler’s Law are a consequence of his theory of gravity?
Isaac Newton
What criteria must be met for an object in the Solar System to be called a planet?
Orbits the sun, nearly round shape, has cleared its orbit
What event involving Venus was used to determine the length of an astronomical unit?
the transit of venus
What planet has the greatest orbital speed?
Mercury (88 Earth Days)
Why do the Moon and the Sun have the same angular size in the sky?
The sun is about 400 times farther away from Earth than the Moon and is also 400 times larger than the Moon
Which planet has the highest densitty?
Earth
Which planet has the lowest density?
Saturn
Which planet has the highest albedo (brightness)?
Venus
What is obliquity?
The angle between a perpendicular to its orbital plane and its spin axis - the tilt of its axis
Which planet has the shortest synodic day?
Mercury, 116 days
Which planet has the longest sidereal day?
Venus, 243 days
What are requirements for a planet to have a global magnetic field?
The interior region of electrically conduction fluid, convection in that layer, moderately rapid rotation
Which planet has the most moon?
Saturn
What is velocity?
Speed and direction of motion
What is acceleration?
Change in velocity, increase, decrease or change in direction
What is force?
a push or pull
What is mass?
the amount of matter in an object
How can we tell if a net force is acting on an object?
Any change in the objects state of motion
Does the Moon accelerate as it orbits the Earth?
Yes, gravity makes the moon accelerate all the time
How is the force of gravity affected if the mass of one of the objects is doubled?
The force of gravity between them is doubled
How is the force of gravity affected if the distance between the two objects is doubled?
Reduce to 1/4 of the initial force
Describe how to put a cannon ball into orbit.
firing it horizontally from a mountain so high that its peak is above the Earth’s atmosphere
What is the barycenter of two objects?
Common center of mass
Why does the Sun wobble in space?
As the sun orbits this moving barycenter, it wobbles around
What are gravitational assists and how are they used in space exploration?
Interaction with a planet is used to change the speed and trajectory of a spacecraft
Why are gaps found in the asteroid belt?
Caused by the orbital resonances between Jupiter and the asteroid belt
What is a chaotic orbit?
An orbit that can change in a largely unpredictable manner or one where a tiny change in the position and/or velocity of the orbiting body will produce major changes in the orbit
How much more light gathering power does an 8-inch telescope have compared to a 4-inch telescope?
4 times the amount
What is resolving power?
ability to discern details
What is the purpose of adaptive optics?
To correct for distortions in light waves caused by atmospheric turbulence
How does adaptive optics work?
Measuring the distortions in a wavefront and then using a deformable mirror to change its shape and compensate for those distortions
What advantages does the Hubble Space telescope have over telescopes located on the surface of the Earth?
There is less distortion from atmospheric turbulence resulting in a clearer view
Why can you see more stars in rural areas than in urban areas?
There is less light population
What are the advantages of a bigger telescope?
Bigger telescopes can capture more light and have higher resolution
Why are there no X-ray telescopes located among the Mauna Kea observatories?
X-radiation is absorbed by the Earth’s atmosphere, preventing X-rays from reaching the Earth’s surface
Where is the Extremely Large Telescope located?
Chile
Where is Gemini North located?
Hawaii