Chapter 3 Quiz Astrology 103
1.) An astronomer finds an object at a distance of 6.8 AU from Earth. Based on the distance, which of the
following is this object most likely to be?
A comet in our solar system
2.) If a radio message were sent toward the nearest star to the Sun and a reply were sent back
immediately on receipt of the message by intelligent beings from a planet near that star, how long after
transmission would we have to wait for a reply?
8.6 years
3.) In 2004, an inhabitant of a planet orbiting a distant star observes the flash of the first nuclear
explosion which occurred in July 1945. Approximately how far away is his solar system from earth?
17.1 pc
4.) If an extraterrestrial being were to send a signal to Earth immediately to confirm the sighting in 2004
of a nuclear explosion on Earth in July 1945, and we were ready to receive such a message, when would
we expect it?
2063 A.D.
5.) The following distance units, arranged in size from smallest to largest, are:
km, AU, ly, pc
6.) How long does it take light to travel from the Sun to Earth?
nine minutes
7.) We know the properties of hydrogen atoms well from studying them in laboratories on Earth. A
fundamental idea in astronomy is that:
a hydrogen atom anywhere else in the universe is the same as it is here.
