Flashcards in Lecture 6 Deck (39):
What is the approximate mass of planet 9?
Approximately how long is Planet 9's orbit?
10,000 to 20,000 years
How was Uranus discovered and by whom?
Herschel, via his telescope, in 1781
How was Neptune discovered?
By calculations based on anomalies in Uranus's orbit
What was one of the earliest pieces of evidence for planet 9?
Elongated orbits of some kuiper belt objects all tilted and elongated in the same direction
Is P9 a typical planet?
Yes, most planets have a mass between 1 and 10 of Earth's
What would planet 9 explain?
Some of the oddities in the solar axis, some of the odd orbits of kuiper belt objects
What is refraction?
It is the bending of light
What parts of the eye make up the "Telescope"?
Cornea and Lens
What is the effect of refraction on parallel rays?
It makes them converge in a focal point
How do Daguerrotypes work?
A copper plate with silver and iodine fumes, which is light-sensitive
What star was first captured in an image?
Vega, in 1850
What are the limitations of photomultiplier tubes?
They can only measure one light-source
What are the two most important parts of a telescope?
The light-collecting area and the angular resolution
A larger light-collecting area means...
greater amount of light in a shorter amount of time
A larger telescope's angular resolution can...
take in greater detail
Why do stars appear to have a finite size in a telescope?
Because light is diffracted in the telescope aperture
What ultimately limits resolution?
Interference of waves in a telescope
What are the two basic types of telescopes?
Reflecting and Refracting
What is the difference between a reflecting and a refracting telescope?
Lenses in a refracting telescope are glass, lenses in a reflecting telescope are mirror
Are most modern telescopes refractors or reflectors?
Reflectors, because making large glass is too cumbersome
What are the three types of foci?
Newtonian, Cassegrain, and Nasmyth
What is unique about a Newtownian focus?
it is towards the top of the telescope
What is unique about a Cassegrain focus?
It is at the butt of the telescope
What is unique about the Nasmyth focus?
It is towards the bottom, on the side of the telescope
What are the four uses of telescopes?
Imaging, Photometry, Spectroscopy, Timing
What is the act of imaging?
taking photos of the night sky with a camera
What is the act of photometry?
Recording the brightness of a source.
What is the act of Spectroscopy?
Recording the light divided into spectra, to reveal information about the composition of objects
What is the act of timing?
Recording changes in brightness over time
Whose was the biggest early telescope?
Whose telescope was bigger than Herschel's?
Lord Rosse's leviathan
What was the biggest telescope in America during the mid-1800s?
Harvard's 15" refractor
What was the biggest working refractor?
What are the four criteria for good earth-based observations?
High, dark, dry, cold
What about the atmosphere makes it difficult to observe from the ground?
Hot and cold air refract light differently, and the atmosphere is a constantly shifting mix of hot and cold air.
What method can telescopes use to minimize the interference of the atmosphere?
What kind of telescopes *Need* to be in space?
Radio, gamma, x-ray, and neutrino telescopes