Astronomy – Flashcards

The ecliptic is a. the centerline of the zodiac b. the projection of earth's orbit on the sky c. the apparent path of the sun around the sky d. all of these

The point in Earth's orbit where Earth is farthest from the sun is known as a. precession b. aphelion c. the winter solstice d. perihelion

A solar eclipse may occur a. when the moon is full b. when the moon is first quarter phase c. when the moon is 3rd quarter phase d. when the moon is new

Which of the following causes seasons on Earth? a. the eleven-year sunspot cycle b. Earth being closer to the sun during out summer and farther during our winter c. the tilt of Earth's axis d. the sun's varying light output

Which of the following people did NOT accept a heliocentric model for the universe? Kepler a. Newton b. Copernicus c. Tycho d. Galileo

In pre-Copernican astronomy, it was almost universally believed that a. Earth was at the center of the universe. b. the planets traveled in elliptical orbits about Earth. c. the center of the universe was the sun with the Milky Way representing other distant planets. d. the sun was at the center of the universe.

Galileo used a telescope to discover spots on the sun. a. moon-like phases of Venus. b. craters on the moon. c. moons around Jupiter. d. all of these.

____ has (have) wavelengths that are longer than visible light. a. Infrared radiation b. Gamma rays c. Ultraviolet light

Astronomers build optical telescopes on tops of mountains because a. the seeing is better. b. gravity is less on the tops. c. land is cheaper. d. CCDs work better with a beautiful mountain view.

Which of the following features of a telescope determines its light-gathering power? a. the focal length of the objective b. the diameter of the objective c. tength of the telescope tube d. the focal length of the eyepiece

A telescope whose objective is a lens and contains no mirrors is a(n) ____ telescope. a. compound b. deflecting c. refracting d. reflecting

An atom that is excited a. can emit a photon when the electron moves to a higher energy level. b. is an isotope. c. can emit a photon when the electron moves to a lower energy level. d. is also ionized.

The lowest energy level in an atom is a. the ground state. b. the absolute zero temperature. c. the ionization level. d. responsible for Doppler shifts.

Which of the following cannot be determined from the spectrum of a star? a. radial (along line of sight) velocity b. tangential (perpendicular to line of sight) velocity c. chemical composition d. surface temperature

The Doppler effect states that the motion of any object can a. change the speed of light emitted from the object. b. make the object appear hotter. c. shift the wavelength of spectral lines. d. enhance the chemical composition of the object.

What is the order of star colors with increasing temperature? a. blue, yellow, red b. red, blue, yellow c. yellow, red, blue d. blue, red, yellow e. red, yellow, blue

The largest structures we know about in the universe are (A) star clusters. (B) walls and filaments of galaxies. (C) constellations. (D) galaxies. (E) galacton megatherium closures.

The distance from the Earth to our sun is (A) one light year (1 ly). (B) one astronomical unit (1 AU). (C) one parsec (1 pc). (D) 6.8 x 1040 m. (E) one fathom.

Say that each day you track the place on the eastern horizon where the sun rises. The day upon which it rises the farthest to the south is the (A) winter solstice. (B) autumnal equinox. (C) summer solstice. (D) vernal equinox. (E) winter equinox

The largest telescopes in current use have mirrors with diameters of about (A) 3 m. (B) 30 m. (C) 10 m. (D) 1 m.

The angular size (from side-to-side) of a fingernail held at arm's length is about (A) 0.25 degree. (D) 2 degrees. (B) 10 degrees. (E) 1 degree. (C) 1 minute of arc

One odd thing about the magnitude scale astronomers use for the brightness of stars is that a bright star (A) could have a magnitude of zero. (B) could have a magnitude like 5,000,000,000. (C) has no magnitude, since the numbers only go from 1 to 1,000,000.

For the moon to go from full to new takes about (A) one week. (C) two weeks. (B) four weeks. (D) three weeks.

To modern astronomers, the term "constellation" means (A) the same as a "galaxy." (B) a region of sky. (C) a cluster of stars that are close together. (D) a pattern of stars.

As viewed from Earth, the angular size of Earth's moon is about (A) 0.5 degrees. (D) 2 degrees. (B) 10 degrees. (E) 5 degrees. (C) 1 degree.

The time for the precession of Earth's axis to describe one full circle in the sky takes about (A) one solar year. (B) one day. (C) 26,000 years. (D) one lunar month. (E) 56 years.

Star A is magnitude 4.30, and star B is magnitude 6.40. By what factor is one brighter than the other? (A) 3.31 times brighter. (D) 17.4 times brighter. (B) 6.92 times brighter. (E) 1.42 times brighter. (C) 2.75 times brighter.

The phase of the moon that looks like this (when viewed from Angwin) is called (A) first quarter. (B) waxing crescent. (C) waxing gibbous. (D) waning crescent. (E) waning gibbous.

How many asterisms are there? (A) 88. (B) 336. (C) 808. (D) 184. (E) There is no fixed number, since asterisms are not official.

The person who found a mathematical formula that exactly describes planetary motion was (A) Ptolemy. (D) Tycho. (B) Galileo. (E) Newton. (C) Kepler

The moon orbits Earth at an average distance of 384,000 km. A crater with an angular size of 15 seconds of arc (when viewed from Earth) is (A) 13 km across. (D) 11 km across. (B) 47 km across. (E) 28 km across. (C) 8.0 km across.

A lunar eclipse happens during (A) any phase of the moon. (B) a waning gibbous moon. (C) a new moon. (D) a full moon. (E) a waxing crescent moon.

the 85 cm (diameter) main mirror has a focal length of 270 cm. The eyepiece has a focal of 1.1 cm, and its diameter is 0.8 cm. The best resolution one could ever hope for with this instrument would be (A) 0.18 seconds of arc. (D) 8.5 seconds of arc. (B) 0.14 seconds of arc. (E) 1.1 seconds of arc. (C) 0.043 seconds of arc.

the 85 cm (diameter) main mirror has a focal length of 270 cm. The eyepiece has a focal of 1.1 cm, and its diameter is 0.8 cm. As configured, the magnification of this telescope is (A) 270 ×. (D) 245 ×. (B) 338 ×. (E) 120 ×. (C) 3.17 ×

the 85 cm (diameter) main mirror has a focal length of 270 cm. The eyepiece has a focal of 1.1 cm, and its diameter is 0.8 cm. Compared to the instrument above, a small telescope with a 4.0 cm (diameter) main lens would gather (A) 21 times less light. (B) 2.4 times less light. (C) 4,600 times less light. (D) 450 times less light. (E) 3,000 times less light.

The apparent once-a-day circling motion of stars about the Earth is caused by (A) Earth's orbiting around the sun. (B) the stars moving around the Earth. (C) the moon orbiting around the Earth. (D) Earth's rotation.

. The apparent once-a-year motion of the sun through the background stars is caused by (A) Earth's orbiting around the sun. (B) the stars moving around the Earth. (C) the moon orbiting around the Earth. (D) Earth's rotation. (E) Oops. The question isn't correct - the sun does not appear to move through the stars on a yearly basis.

The "declination" of a star gives its (A) north-south position in the sky, measured from the celestial equator in degrees. (B) north-south position in the sky, measured from the celestial equator in hours and minutes. (C) east-west position in the sky, measured from the vernal equinox in degrees. (D) east-west position in the sky, measured from the vernal equinox in hours and minutes. (E) brightness.

The fact that the moon's orbit around the Earth is tipped with respect to Earth's orbit around the sun explains (A) why the moon goes through different phases. (B) the length of a lunar month. (C) why a day is added to the year about every four years. (D) why we don't have two eclipses every month. (E) the motions of the tides.

. Which of these is true of an altazimuth mounting (with a clock drive) for a telescope? (A) Two motors are needed, and they turn at different speeds. (B) The mounting is mechanically difficult, because the weight of the telescope is off center. (C) This type of mount is only used for small amateur telescopes, typically eight inches or less. (D) One motor is needed, and it turns at a speed of one revolution in 24 hours. (E) Oops. The wording of the question is incorrect, since a clock drive cannot be used with an altazimuth mount.

The (modern) explanation for what we call retrograde motion is (A) that planets sometimes move backwards. (B) that faster planets overtake and pass slower planets. (C) that planets move on a combination of small epicycles and larger deferents. (D) that gravity makes planets go backwards. (E) Kepler's third law.

Say that the calendar system in a certain country uses a cycle of 12 lunar months, with each month starting at a new moon. The long-term effect of this scheme is that (A) a given month like "June" would fall in different seasons in different years. (B) the summer solstice would always fall on June 1. (C) you could never tell what phase the moon was unless you had a chart or calendar to tell you. (D) the vernal equinox would fall on March 20, 21, or 22, depending on the year. (E) winter months would be longer and summer months would be shorter.

One of Isaac Newton's important contributions to astronomy was his (A) accurate measurements of planet positions. (B) "harmonic law" of planetary motion. (C) discovery of the moons of Jupiter. (D) belief that the Earth is at the center of the universe, and all the planets orbit around it. (E) discovery of the law of universal gravitation.

In the lab the hydrogen-alpha line has a wavelength of 656.28 nm. If we see that in the light coming from a star the same line has a wavelength of 659.31 nm, we (A) would conclude that the star is moving toward us. (B) would conclude that the star is moving away us. (C) could make no conclusions about the star's motion

(T) (F) Assuming clouds don't get in the way, the number of persons that can see a given lunar eclipse is about half the people on Earth.

(T) (F) The path in the sky through which the sun appears to move throughout the course of a year is called the celestial equator.

(T) (F) On average, a lunar eclipse happens about once every 7 or 8 years.

Star A is 180 times brighter than star B. What is the difference in their magnitudes?

Say that Jupiter, with its diameter of 142,000 km, was located where Mars now orbits. What would be the angular size of (the newly-relocated) Jupiter during a close approach, when its distance would be 79,300,000 km? Would we be able to see Jupiter as a round object with our unaided eye, or only as a point of light? Explain.