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Extrasolar Planets Review Game Questions
1) Compared to the Earth, most of the planets discovered around other stars are _______________ massive and
orbit very_______________ from the star.
more or less
close or far
2) What kind of planets does the transit method of planet detection works best for? (describe the size of the
planet, the size of star, orbit distance and orientation)
3) Which planet search technique is currently best suited to finding Earth-like planets?
4) What does the discovery of hot Jupiters tell us about our understanding our own Solar System?
5) The astrometric technique of planet detection works best for detecting what type of planets? (describe the size
of the planet, the size of star, orbit distance and orientation)
6) Which planet can we see occasionally transit across the face of the Sun?
7) How do we think the "hot Jupiters" around other stars were formed?
8) Why are many of the newly detected extrasolar planets called "hot Jupiters"?
9) What is astrometry?
10) What does the depth of the dip in a star's brightness due to the transit of a planet depend on most directly?
Diagram 1
11) Refering to Diagram 1, compared to the original planet (Graph 1) which graph shows a planet orbiting faster?
12) Refering to Diagram 1, compared to the original planet graph (Graph 1) which graph shows a larger planet?
13) About how long ago were the first planets around other Sun-like stars were discovered?
14) A star like our Sun has a jovian transiting its disk every 5.7 days, and the star dims by 9% every time this
occurs. How large must this Jovian be, given that the diameter of Jupiter is about 1/10 the Sun's diameter?
15) What do astronomers use to determine the composition of a planet?
16) Why do some scientists think that Jupiter's existence may have been critical for life to evolve on Earth?
17) What defines the habitable zone around a star?
18) At present, what is the primary way that the search for extraterrestrial intelligence (SETI) is carried out?
19) The Voyager I and II spacecraft visited the jovian planets in the 1980s. When will they reach the distance of the
nearest stars?
20) Name three things we find when we compare our own solar system with other systems that we’ve found.
21) Multiple-planet systems have been identified around other stars via the _____________________ technique.
22) A planet's size can be determined by observing its ____________________ across a star.
23) A sun-like star is a __________________ times brighter than an earth-like planet.
24) The first extrasolar planet detected orbiting a main sequence star was ____________________ which orbited its
star every 4.2 days.
25) In order to use the Doppler method of detection it is best to view planetary orbits ________________ to our
line of sight.
26) All of the planets found orbiting other stars have been most similar to ________, except most of them have
been much closer to their star than this planet is to the Sun.
27) All the planets found orbiting other stars to date have been similar to Jovians, except that most have been
much ________ in temperature.
28) Viewed from far away, the transit of the Earth would cause the Sun's brightness to dim by approximately one
part in ___________.
29) In the rare case a planet ________ its star, we can find the size, mass, and density of the body passing in front
of its sun.
30) In comparing our solar system with others now known, we find that most other planets have more ________
orbits than the circular ones around our Sun.
31) Briefly explain the paradox of the question "Where are the aliens?"
32) Calculate how much (as a percentage) an Earth transit would reduce the light from the Sun as viewed from a
distant planetary system.
33) Briefly describe the three most commonly used methods of indirect planet detection.
34) The star Rho Cancri B has about the same mass as our Sun, and the planet discovered around it orbits
somewhat closer than Mercury orbits our Sun. The mass of the planet is estimated to be 1.1 times the mass of
Jupiter. Why, according to our theory of solar system formation, is it surprising to find a planet the size of Rho
Cancri B's planet orbiting at this distance?
35) Life depends upon water as the critical solvent partially because it is ________ over a large range in
temperatures.
36) The theory that complex chemicals necessary for life could evolve naturally from simpler molecules is known
as:
37) What is the Drake Equation used to calculate?
38) The most poorly known factor in the Drake Equation is ________.
39) In addition to the proper chemistry, it is ________ that determines the feasibility of life on a given planet.
Extrasolar Planets Review Game Answers
1) more, close
2) big planets in close, edge-on orbits around small stars.
3) transit
4) It shows that we do not fully understand the formation of our Solar System.
5) massive planets around nearby stars in face-on orbits
6) Mercury (note: transits are rare but we see about 13 per century for Mercury and only about 2 per
century for Venus)
7) They formed as gas giants beyond the frost line and then migrated inwards.
8) Their masses are similar to Jupiter but they are very close to the central star and therefore hot.
9) measuring the positions of stars on the sky very precisely
10) the planet's size.
11) Graph 2
12) Graph 4
13) about a decade ago.
14) For Jupiter:
So Jupiter blocks about 0.01 x 100% = 1% of the sun’s light. To block 9% of the sun’s light this object must be nine
times larger than Jupiter.
15) spectra
16)
It kicked out many comets from the inner solar system through gravitational encounters, thus ending the
heavy bombardment phase of the solar system.
17) the region around a star where liquid water can exist on planetary surfaces
18) by using radio telescopes to search for signals from extraterrestrial civilizations
19) about a hundred thousand years from now
20) that most orbits are less circular than planets around our Sun, hot Jupiters orbit even closer to their stars than
Mercury is to our Sun, even multiple planets are found in some systems.
21) Doppler
22) transit.
23) billion
24) 51 Pegasi b
25) edge- on
26) Jupiter
27) hotter
28) ten thousand
29) transits
30) eccentric
31) If we survive and decide to become interstellar travelers, we are probably capable of it. Because our solar
system formed some 5 billion years after the galaxy formed, it therefore seems likely that other civilizations
should have evolved and developed interstellar travel long ago. The paradox is that we have not yet had any
contact with such civilizations.
32) A planet of radius R blocks an area πR2 of the star. If the star has radius R*, then its area is πR *2 and the
fraction of light that is blocked is (πR2)/(πR*2) = (R/R*)2. For an Earth transit of the Sun, we use R=6,378 km and
R*=695,000 km from Appendix E to determine that the blocked fraction = (6,378/695,000)2 = 8.4x10-5 = 0.008%.
33) The Doppler technique measures the periodic change in velocity of a star due to the motion of a planet around
it. The astrometric technique measures the periodic change in the position of a star on the sky as it responds to the
motion of a planet around it. The transit technique measures the dip in star brightness as the planet moves in
front of the stellar disk.
34) In the nebular theory, Jovian planets form beyond the frost line. In our solar system, this was beyond the orbit
of Mars, so it is surprising to find a Jovian planet orbiting so close to its star.
35) liquid
36) chemical evolution.
37) number of technological civilizations in a galaxy like our Milky Way.
38) average lifespan of a technological civilization.
39) temperature