ASTR - Chapter 21
The most common planets have radii between __________ that of Earth, nicknamed __________, sizes for which we have no examples in the solar system.
1.4 and 2.8, super-Earths
Kepler's initial mission monitored ____________ stars.
100,000
How long would aliens from Alpha Centauri have to watch our star to see the full range of movement of the Sun caused by Jupiter?
12 years
Astronomers have discovered roughly __________ extrasolar planets.
4000
The first planet detected using the Doppler method completes its orbit around the star ____________ every _________.
51 Pegasi, 4.2 days
Astronomers estimate that __________ of stars have at least one planet.
70%
The __________ predicts that the spectrum of a star will shift back and forth as it moves ______________.
Doppler Effect, towards and away from Earth
Astronomers have not found any planets inside the habitable zone of their stars.
False
Most detection methods for finding extrasolar planets are direct methods.
False
The Kepler spacecraft used the Doppler method to detect exoplanets.
False
There are no planets in the habitable zone of the Kepler-62 system.
False
Astronomers are focusing their search for life on __________ type stars.
G and K
______ type are the most common type of stars, representing _______ of observed stars.
M, 80%
The Kepler spacecraft was designed to detect planets as small as _________ and orbits of less than ___________ days.
Mars, 400
Kepler found that our Solar System is different from many of the planetary systems that it found. What is the main difference?
Our Solar System does not have medium planets, like super-Earths.
___________ are when a __________ passes in front of a star.
Transits, planet
Hotter stars have wider habitable zones.
True
The center of mass of the Earth-Moon system is only 1700 km below the surface of the Earth.
True
Which of the following is NOT a stellar requirement for life?
a very large mass star
Which detection method looks for the "wobble" - movement back and forth in the sky- in a star caused by the gravitational pull of the planet?
astrometric method
Astronomers monitor the _____________ of a star to detect planets with the transit method.
brightness
A planet and its star revolve about their common ______________.
center of mass
Which of the following is NOT a property of extrasolar planets that can be measured by astronomers?
color
An ______________ is a planet found outside of our Solar System.
exoplanet
The _____________ is defined by distance from their star, so the planet is not too _____________.
habitable zone, hot or cold
Direct imaging of exoplanets works best for young gas giant planets that emit __________ light and reside at _________ separations from their host stars.
infrared, large
Which is NOT a requirement for a habitable planet?
large amounts of sulfur
Direct detection of planets favor planets that are _________ and _____________.
large, far away from their star
The __________ in the Kepler data and Doppler observations make ________ planets easier to find than small ones, and short-period planets easier than long-period planets.
selection effects, large
For several hundred exoplanets, we have been able to measure both the ________ of the planet from transit data and its _________ from Doppler data, yielding an estimate of its _________.
size, mass, density
The Doppler method of detection looks for the motion of the star _____________.
towards and away from the Earth
A ___________ is when a planet crosses in front of its star, causing the star to ______ slightly.
transit, dim
