Mapping the Universe Flashcards
what type of science is astronomy?
An observable science - we have to use what the Universe gives us
What drives discoveries in astronomy?
New observations - higher resolutions, deeper, new type of observations
What was one of Galileo’s first discoveries?
That Jupiter had moons
What is the best definition of multimessenger astronomy?
Using a combination of electromagnetic radiation, gravitational waves, and particles (like neutrinos) to do astronomy
How were Pulsars first discovered?
From radio observations
What does the nightsky being black tell you
That the universe had a beginning
Who discovered light outside the visible spectrum?
William Herschel
How did William Herschel discover there was light outside the visible spectrum?
By putting thermometers outside the visible light, still showed and increase in temp - there was still energy
Why are there different colours of light?
What is amplitude of a wave?
The size of a wave - the larger the amplitude, the higher the energy (for light the larger the brighter)
What is the wavelength of waves?
The distance between one cycle and the next (measured in meters)
What is Period in terms of waves
The time taken for one cycle (measured in seconds)
What is meant by the frequency of waves?
the number of cycles per unit of time (measured in hertz HZ)
What is the speed in terms of waves?
How quickly the wave travels (m/s)
How are the period and frequency of a wave related (time variation) ?
f = 1/T
Means the longer period means lower frequencies and vice versa
What is the wave equation? what does is describe the relationship between?
speed is defined as the distance travelled divided by the time taken. For one cycle of a wave, it travels by one wavelength in one period
speed = wavelength x frequency
Let us consider a sound wave. If we played a middle C, the frequency is 262 Hz. The speed of sound in air is about 340 m/s. What is the sound wave’s wavelength?
340(m/s) divided by 262 Hz = wavelength
1.3 m = wavelength
What type of wave is light?
An electromagnetic wave
What does the direction of the electric field give?
The polarization
What is blackbody emission
the emission of light due to temperature
What is Wien’s displacement law?
described the relationship between the temo of a black body and the wavelength at which it emits the most radiation
max wavelength = wien’s displacement constant/ absolute temperature
What is the equation for the speed of light in a material?
v = c/n
where n is the refractive index
What is refraction?
The bending of a wave when it travels through a medium of a different refractive index (wave speed)
