Astro101 Quiz 5
What can all the various kinds of light be described as?
Waves
Extrasolar Planets
Planets orbiting stars other than the Sun
A second of arc is
1/3600 degree
1 parsec (pc)
= 3.26 LY
Who is Joseph von Fraunhofer?
A German physicist who observed and recorded over 600 dark bands in the spectrum of the Sun.
Electromagnetic Radiation
A unified entity in which the differences we observe are caused only by changing frequencies (or wavelengths)
Who is William Huggins?
An English amateur astronomer who identified these lines in the Sun with some common elements.
Continuous Spectrum
An array of all wavelengths or colors of the rainbow
How fast does Light travel?
At 300,000 km/s So there is a delay between when light leaves its source and when it reaches an observer.
Why does Light come in different frequencies (wavelength)?
Because it is generated by events happening with different amounts of energy.
Particle
Energy localized in a packet
Wave
Energy spread out
What is the rate at which the cycles of the wave motion are repeated?
Frequency, f.
Who was the first person to use spectroscopy to identify an element in the Sun?
Gustav Kirchhoff
Doppler Effect
If a light source is approaching or receding from the observer, the light waves will be respectively, crowded more closely together or spread out.
Emission Line Spectrum
It appears as a pattern or series of bright lines (A bright line)
Absorption Line Spectrum
It consists of a series or pattern of dark lines (A dark line)
Proper Motion
Motion across the sky
Radial Velocity
Motion toward or away from us
The more massive the planet or the closer its orbit to the star..
The greater its gravitational pull and hence the star's movement.
The smaller the mass of a body in such a system..
The larger the orbit.
Hα line
The most prominent spectral feature due to hydrogen at visible wavelengths (λ0 = 6563 Å)
What if you increase the frequency of the wave?
The wavelength decreases.
A star has a measured parallax of 0.1 arcsec. How far away is it in parsec? In LY?
Using the formula D = 1/p D = distance (in parsec) p = parallax (in arcsec) = 10 pc
Y/N: All electromagnetic waves move at the same speed in space
Yes
Blueshift
decrease in wavelength
Redshift
increase in wavelength
