exoplanets grade5 2015
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Exoplanets:Finding Other Worlds Around Other Stars
Paul GreenCenter for Astrophysics
• What's the nearest star?
• Different kinds of stars• hot and cool• large and small• far and near
• Difference between a star and a planet?• Stars shine, planets don't• So why can we see planets?
• There are different kinds of planets too!
Our Solar System
(Comparing Sizes)
Terrestrial (Rocky) Planets
Gas Giant Planets
Planets’ Distances from the Sun
How the Solar System FormedAbout 5,000,000,000 years ago
Why do you think the rocky planetsare close to the Sun, and the gas giants far away?
Exoplanets
Do you think there are planets around other stars?
Finding Exoplanets
Like a mosquito near a far away headlight, planets around other stars are too faint to be seen.
So how can we find them?
TIME
BRIGHT
NESS
00
Imagine you have a light sensor aimed a lamp.
What would the transit of a book look like if you made a graph of brightness vs time?
Like this?
TIME00
BRIGHT
NESS
What would the transit of a planet look like if you made a graph brightness vs
time?
TIME00
BRIGHT
NESS
TIME00
This is a “light curve.”
How are the planet’s size and orbital period
shown in the light curve?
BRIGHT
NESS
What’s This?
NASA’s Kepler Mission
A Kepler Planetary Transit Lightcurve
3.2 day period
5 hour eclipse
21
Transiting Planets pre-Kepler
Orbital Period in days
Size
Rel
ative
to E
arth
2222
Transiting Planets as of June 2010Data: May-Sep 2009
Orbital Period in days
Size
Rel
ative
to E
arth
Jun 2010
23
Transiting Planets as of Feb 2011Q0-Q5: May 2009 - Jun 2010
Orbital Period in days
Size
Rel
ative
to E
arth
Jun 2010 Feb 2011
24 Orbital Period in days
Size
Rel
ative
to E
arth
Transiting Planets as of Dec 2011Q0-Q6: May 2009 - Sep 2010
Jun 2010 Feb 2011 Dec 2011
Different Types of Stars
Do blue stars always look fainter than red stars?
28
What’s Next?• Kepler has discovered thousands of planets, now what?
• There are big surprises, like gas giants in close orbits,and enormous super-earths in large orbits.
• Time to search for signs of life!
• Giant telescopes are being built right now!
Habitable Zone
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