🔭W5 L2 - The nature of light - light & atoms as messengers Flashcards
What does a keogram measure?
Length of day and night over a year
Define photometry
Study of the intensity of light
Is the star brightness magnitude scale linear or logarithmic?
Logarithmic
Define “apparent magnitude”
How bright an object appears in the sky from Earth
Define absolute magnitude
How bright an object appears at a distance of 10 parsecs
On the apparent magnitude scale, does a bright object have a bigger or smaller number?
Smaller, even negative
What is the apparent magnitude of the Sun from Earth?
-27
What is the absolute magnitude of the Sun?
3
Light can be split by a prism, what’s another tool that splits it?
Diffraction grating spectrograph
At 0 Kelvin what colour is a black body object?
Black
What colour progression does a black body emit?
Red, orange, yellow, white, blue
As an object gets hotter, are wavelengths long or short?
Short (bluer)
Why is the sun’s spectrogram deficient in the UV range?
Atmospheric ozone absorbed it
What does absorption spectroscopy reveal?
The wavelength absorbed by an electron jumping to a higher orbit
What does emission spectroscopy reveal?
The wavelength emitted by an electron dropping to a lower orbit
Where was helium first discovered?
In the Sun via spectroscopy (helios)
Are radio telescopes small or large?
Large
How succesful is infra-red astrponomy at the surface?
Poor, water in atmosphere absorbs IR
Name one dry continent where infrared astronomny is conducted.
Antarctica
Name one Earth-based IR observatory
SOFIA
Name two space-based IR observatories
Herschel, James Webb
At UV, XR, gamma ray short wavelengths how does light behave?
Like a particle
Name one gamma ray observatory
Fermi Gamma-Ray observatory
Name one UV observatory
Swift
