Lecture 1 Flashcards
what is the composition of the universe
27% dark matter, 68% dark energy, 5% ordinary matter
what is ordinary matter made up of
4% hydrogen and helium, <1% stars, <1% other
what is dark matter
matter that doesn’t interact with light
what is the scientific method
observe universe
create a model to explain the observations
make predictions
test predictions against other observations
refine & repeat
what is the main tool to observe the universe
telescope
what is a telescope
a device to collect & analyse light
lens diameter for galileos telescope and year
0.06m 1620
lens diameter for Herschels telescope and year
1.26m 1789
lens diameter and year for hookers telescope
2.5, 1917
GTC lens diameter and year
10.4m 2006
ELT telescope diameter and year
39m , under construction
what does a telescope do with images
take a picture of a region in a single “band”, digitally combined to give a colour image
what does a telescope do with spectra
break the light down finely into individual wavelengths
what is the break down of solar radiation
5% UV, 42% Visible light, 53% infrared
UV wavelength range
0-380nm
visible light range
380-780nm
infrared range
780nm +
em sprecturm
radiowave, microwave, infrared, visible, uv, x ray, gamma
what is the use of different wavelengths for viewing galaxies
shows different details
what do radio/x rays mostly show on imaging of galaxies
black holes & stars
what time scales do stars evolve on
1 mil year time scales
what is lookback time
describes how long time takes to Reach us
lookback time of the moon
1.5s
lookback time of the sun
8min
lookback time of the nearest other star (alpha centauri)
4 years
lookback time of centre of Milky Way
25k years
lookback nearest big galaxy ( Andromeda)
2.5mil years
Look back time of most distant galaxy known
13.5 billion years
