Sun-centered universeGalileo’s observations. 1. The Moon’s
surface
Moon not a perfect “heavenly body”
Sun-centered universeGalileo’s observations. 2. Jupiter’s
moons
Jupiter has moons!> there are things that do not orbit the Earth!
Sun-centered universeGalileo’s observations. 3. Phases of
Venus
Venus has phases, just like the MoonAttributed them to Venus’ motion around the Sun
Hot questions of recent time
•how do stars work?
•how are chemical elements made?
•how big is the universe?
•what are “spiral nebulae”?
•what are quasars?
•are there planets around other stars?
•...
Hot questions of today and tomorrow
1.how do planets form?
2.how do stars form?
3.how do galaxies form?
4.what were the first objects to form after the Big Bang?
Three things that count
1.sharpness of image
•resolve structure - get into the details 2.wavelength coverage
•go after different physical processes in the same object
3.ability to collect lots of light
•go after faint objects •lots of detail on brighter objects
1.sharpness of image
•resolve structure - get into the details 2.wavelength coverage
•go after different physical processes in the same object
3.ability to collect lots of light
•go after faint objects •lots of detail on brighter objects
Three things that count
1.sharpness of image
•resolve structure - get into the details 2.wavelength coverage
•go after different physical processes in the same object
3.ability to collect lots of light
•go after faint objects •lots of detail on brighter objects
Three things that count
The eye vs Keck
eye Keck advantage
photons/sec entering “instrument” : π(5/2 mm)2 π(10/2 m)2 4,000,000 x
of these, actually detected: ~1% ~90% 90 x
persistence (Integration time): < 1 sec >1 hr 3600 x
bottom line: ~1.3x1012 x
Location, location, location
•important for sharpness of image•clarity of atmoshpere (“seeing”)•or no atmosphere at all
•ability to detect different wavelengths
•Earth’s atmosphere absorbs light (esp. bad at IR)
•so... get above the atmoshpere
Hot questions of today and tomorrow
1.how do planets form?
2.how do stars form?
3.how do galaxies form?
4.when did the first structures (galaxies, stars...) form in the universe?
ALMA(Atacama Large Millimetre
Array)• at 5000m elevation in the Atacama
desert (Chile)
• location minimizes water vapour in the atmosphere
ALMA(Atacama Large Millimetre
Array)• Capabilities:
• star formation in the early Universe:
• heat emission from dust in distant galaxies
• molecular (cold) gas in distant galaxies
• very high spatial resolution = study internal structures
• large collecting area = high sensitivity
JWST(James Webb Space Telescope)
Next generation space telescope (successor to Hubble)with a 6.5m segmented mirror
JWST(James Webb Space Telescope)
• Capabilities:
• infrared (heat) observations from space
• very high spatial resolution:
• study structural details of distant galaxies
• search for planets around other stars
• large collecting area = very sensitive
• 30-m diameter (duh!)
• 3x bigger diameter than Keck => 9 times more collecting area
• Capabilities:
• huge mirror: extreme light-gathering power
• adaptive optics: resolve very fine details or small separations
• extremely complementary to JWST
TMT(Thirty Meter Telescope)