Oort-cloud comets are so far from the Sun that the gravity of neighboring stars can alter their orbits.
Indicate whether the statement is true or false
Question 2When a formal definition of a planet in the solar system was adopted, Pluto was reclassified as a dwarf planet. What characteristic of planets does NOT describe Pluto?
A) Planets orbit the Sun.
B) Planets are approximately spherical.
C) Planets have cleared the neighborhood around their orbit.
D) Planets orbit in ellipses with low eccentricity.
E) Planets orbit in or very near the ecliptic plane.
Question 3All globular clusters in our Milky Way are about how old?
A) less than a million years
B) ten-fifty million years old
C) one to three billion years old
D) around ten billion years old
E) a variety of ages, from newly born to twenty billions years old
Question 4Explain why stars form only in molecular clouds, the coldest, densest parts of the interstellar medium.
What will be an ideal response?
Question 5Star clusters have been observed within dark nebulae with:
A) optical movies made over decades.
B) radio interferometers.
C) infrared observations.
D) the Chandra X-ray observatory.
E) ultraviolet light creating the emission nebulae.
Question 6Describe how the inflationary model of the early universe, a current matter density equal to the critical density, and dark matter are related.
What will be an ideal response?
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