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Earth-shattering ideas
in astronomy
Dr. Katja Poppenhaeger
Harvard-Smithsonian Center for Astrophysics
Picture credit: Wikimedia Commons
Stars with planets?
Picture credit: NASA / ESA / ESO
Early 1990s:
The race for the first exoplanet
Michel Mayor and Didier Queloz,
Geneva Observatory,
telescope: OHP (France)
Picture credit: BBVA, U Berkeley
Geoff Marcy and Paul Butler,
San Francisco State University,
Lick telescope (USA/California)
Planets around other stars – how to
find them?
Picture credit: Wikimedia Commons / http://www.flickr.com/photos/greyness/3628237515
Finding planets the Doppler effect
How stars and planets move:
Picture credit: Wikimedia Commons
Doppler effect: sound/pitch
Picture credit: www.ircamera.as.arizona.edu
Doppler effekt: colors of light
Picture credit: www.nachi.org
Doppler effect for colors of light
Picture credit: Brooks Cole Publishing
Doppler effect: colors of light
Doppler velocity induced by a planet:
ca. 100 m/s = 40 km/h = 25 mph
The solar spectrum
Picture credit: NASA APOD
Finding planet 51 Pegasi b
Picture credit: K. Poppenhaeger
Finding planet 51 Pegasi b
Picture credit: K. Poppenhaeger
Finding planet 51 Pegasi b
Picture credit: K. Poppenhaeger
Planet 51 Pegasi b
Picture credit: www.exoplanets.org
Planet 51 Pegasi b
“Hot Jupiter”
Picture credite: Martin Richmond
Many Hot Jupiters known to date
Picture credite: Fermilab / J. Steffen
The habitable zone
Picture credit: NASA
Picture credit: NASA
Super-earths in the habitable zone?
?
Star Gliese 581
Picture credit: ESO
Kepler-22 system
Picture credit: NASA
Checking if a planet is in the
habitable zone:
Checking if a planet is in the
habitable zone:
Finding planets transits
(Latin: “it passes over”)
Transit of Mercury in front of the Sun
Picture credit: NASA APOD
Transit of Mercury in front of the Sun
Picture credit: NASA APOD
A peculiar transit...
Picture credit: NASA APOD
A peculiar transit...
Picture credit: NASA APOD
Transits of exoplanets in front of stars
Picture credit: Jeff L. Coughlin
A long-duration transit: planet
HD 80606 b
Picture credit: Winn et al. 2009
Transit of the planet HAT-P-11
Picture credit: Deming et al. 2011
“super-neptune”
The Earth's atmosphere interferes!
Picture credite: A. Hatzes
Transit of the planet HAT-P-11
Picture credit: Deming et al. 2011
Space telescope Kepler
Picture credit: NASA
Kepler's field of view
Picture credit: NASA
A few of Kepler's planets
Picture credit: NASA
Picture credit: F. Fressin
Picture credit: NASA
Confirming planets without mass
measurements
Picture credit: NASA
Kepler's field of view
Picture credit: NASA
Kepler's planets: before
Picture credit: NASA
Kepler's planets: after 3 years
Picture credit: NASA
The expansion of the
Universe
Picture credit: D. Hager and T. Grossman
Idea: The cosmological principle
“The universe is homogeneous and isotropic on
large scales.”
This means:
The universe is pretty much the same everywhere
(homoegneous)
and all directions look the same as well
(isotropic).
We don't occupy a special place in the universe!
Einstein, Friedmann, Robertson, Walker, Lemaitre
The Hubble ultra-deep field
Picture credit: Wikimedia Commons
Picture credit: Wikimedia Commons
Picture credit: Wikimedia Commons
Picture credit: Wikimedia Commons
2 possible scenarios:
1) The universe is expanding
2) The universe is contracting
(a static universe would
require a lot of fine-tuning.)
So let's measure
the speed of galaxies!
Picture credit: NASA APOD, R.C. Kennicutt, ApJS, volume 79, 255-184, 1992
So let's measure
the speed of galaxies!
Picture credit: R.C. Kennicutt, ApJS, volume 79, 255-184, 1992
So let's measure
the speed of galaxies!
Distance: 30 Mpc
Line shift: 20
So let's measure
the speed of galaxies!
So let's measure
the speed of galaxies!
So let's measure
the speed of galaxies!
So let's measure
the speed of galaxies!
Hubble's Law
All galaxies move away from us,
in all directions!
Picture credit: One Minute Astronomer
Expansion of the universe
Picture credit: ESA/NASA
Picture credit: National Science Foundation