Physical Science Astronomy Chapter 26

Rank in order of increasing average density: (a) Uranus, (b) Mars, and (c) Neptune. Rank from least dense to most dense. To rank items as equivalent, overlap them.

A, C, B

Part A: Many scientific discoveries are made by chance. While studying one phenomenon, a scientist may discover a different one. Such was the case when William Herschel discovered the planet Uranus in 1781. Herschel was charting faint stars in the sky, when he discovered something that was not a star. How can astronomers tell the difference between a star and a planet? The following diagram depicts the sky as it would have appeared to Herschel when he first observed Uranus in 1781, as well as the same part of the sky over the next several nights. Label the indicated objects as stars or planets. Drag the labels onto the diagram to identify the star(s) and planet(s).

A: star B: star C: star D: planet

Rank in order of decreasing number of people who have seen a: (a) solar eclipse, (b) lunar eclipse, and (c) new Moon. Rank from most to least. To rank items as equivalent, overlap them.

B, A, C

Rank these planets in order from longest to shortest year: (a) Mars, (b) Neptune, and (c) Earth. Rank from longest to shortest. To rank items as equivalent, overlap them.

B, A, C

Provided following are stages that occurred during the formation of our solar system. Rank these stages from left to right based on when they occurred, from first to last.

First stage: large cloud of gas and dust contraction of solar nebula condensation of solid particles accretion of planetesimals clearing the solar nebula

Part C: The following images show Earth and the four jovian planets of our solar system. Rank these planets from left to right based on their mass, from lowest to highest. (Not to scale.)

Lowest mass: Earth Uranus Neptune Saturn Jupiter Highest mass

Part B: After the discovery of Uranus, astronomers calculated its orbit and predicted its position in the sky using Kepler's laws of planetary motion, which had been known since the early 17th century. However, they soon discovered a small discrepancy between the predicted and actual positions of Uranus. As a scientist, what should you do when presented with such a conflict between prediction and observation?

verify that your observations are correct consider that Uranus may not be a planet consider whether Kepler's laws need to be modified to account for the new observations think about what else might cause the observed discrepancy

Listed following are locations and times at which different phases of the Moon are visible from Earth's Northern Hemisphere. Match these to the appropriate moon phase.

waxing crescent moon: visible near western horizon about an hour after sunset sets 2-3 hours after the Sun sets waning crescent moon: occurs about 3 days before new moon visible near eastern horizon just before sunrise full moon: rises at about the time the Sun sets occurs 14 days after the new moon visible due south at midnight

Listed following are characteristics of the atmospheres of Venus, Earth, and Mars. Match each atmospheric characteristic to the appropriate planet.

Venus: sulfuric acid clouds almost no wind runaway greenhouse effect Earth: atmosphere composed primarily of nitrogen ultraviolet-absorbing stratosphere Mars: extremely low density atmosphere global dust storms

Match the words in the left-hand column to the appropriate blank in the sentences in the right-hand column. Use each word only once.

1. A solar eclipse that occurs when the new moon is too far from Earth to completely cover the Sun can be either a partial solar eclipse or a(n) annular eclipse. 2. Anyone looking from the night side of Earth can, in principle, see a(n) total lunar eclipse. 3. During some lunar eclipses, the Moon's appearance changes only slightly, because it passes only through the part of Earth's shadow called the penumbra. 4. A(n) total solar eclipse can occur only when the Moon is new and has an angular size larger than the Sun in the sky. 5. A partial lunar eclipse begins when the Moon first touches Earth's umbra. 6. A point at which the Moon crosses Earth's orbital plane is called a(n) node

If Earth didn't spin on its axis but still revolved around the Sun, how long would an Earth day be?

365 d

What is the age of the Sun?

5 billion years

Part A: The following images show Earth and the four jovian planets of our solar system. Rank these planets from left to right based on their distance from the Sun, from closest to farthest. (Not to scale.)

Closest: Earth Jupiter Saturn Uranus Neptune Farthest:

Listed following are some distinguishing characteristics of comets, meteors, and asteroids. Match these to the appropriate category of objects.

Comets: form a coma when near the Sun visible in the sky as a fuzzy patch of light that rises and sets with the stars most are located either in Kuiper belt or Oort cloud Meteors: visible in the sky as a bright streak of light for only a few seconds dust particles entering Earth's atmosphere at high speed Asteroids: compositions similar to that of the terrestrial planets typically orbit the Sun at approximately 3 AU

Part C: Starting with the hypothesis that a planet near Uranus was the cause of the orbital discrepancy, scientists had to develop a plan to find the unidentified planet. They started with what they knew about the discrepancies in the orbit of Uranus. Rank the steps in the order that scientists would take to discover the planet. Rank the steps in the appropriate order from first to last.

First: Calculate the mass, orbit, and likely position of the unidentified planet. Use optical telescope to search a region of the sky where the unidentified planet is predicted to be. Compare current observations to existing star charts to locate any new objects. Make continued observations to determine if the new object changes position relative to background stars.

Part C: Listed following are several astronomical objects. Rank these objects based on their density, from highest to lowest.

Highest density: the singularity of a black hole a typical neutron star a one-solar-mass white dwarf a main-sequence star

Part A: Listed following are several astronomical objects. Rank these objects based on their diameter, from largest to smallest. (Note that the neutron star and black hole in this example have the same mass to make your comparison easier, but we generally expect black holes to have greater masses than neutron stars.)

Largest diameter: main-sequence star of spectral type A Jupiter a one-solar-mass-white dwarf the moon a two-solar-mass neutron star the event horizon of two-solar-mass black hole Smallest diameter

Part B: Listed following are several astronomical objects. Rank these objects based on their mass, from largest to smallest. (Be sure to notice that the main-sequence star here has a different spectral type from the one in Part A.)

Largest mass: a typical black hole (formed in a supernova) a typical neutron star a one-solar-mass- white dwarf main- sequence star of spectral type M Jupiter the moon Smallest diameter

Part C: Which of the following statements correctly describes the motion of the particles in Saturn's rings?

Particles in the inner rings orbit Saturn at a faster speed than particles in the outer rings.

Part B: The following images show Earth and the four jovian planets of our solar system. Rank these planets from left to right based on their size (average equatorial radius), from smallest to largest. (Not to scale.)

Smallest radius: Earth Neptune Uranus Saturn Jupiter Largest Radius:

If the Sun were the size of a beach ball, Earth would be the size of a green pea 110 m away. What would be the distance to the nearest star, Alpha Centauri (4.4 light-years away). (Hint: Find the distance to Alpha Centauri in units of AU.)

d=3.0×10^4 km

Part B: Saturn's rings look bright because __________.

light from the Sun reflects off the material in the rings

Part A: Saturn's rings are composed of __________.

lots of individual particles of ice and rock

How many days does sunlight take to travel the 50000 AU from the Sun to the outer reaches of the Oort cloud?

t=290 d

Knowing that the speed of light is 300,000 km/s, find the time that sunlight takes to reach Earth.

t=8.3 min