Essential Cosmic Perspective
9th Edition
ISBN: 9780135795033
Author: Bennett
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 1, Problem 39EAP
Group Activity: Counting the Milky Way’s Stars. Work as a group to answer each part. Note: This activity works particularly well in groups of four students, with each student taking on one of the following roles: scribe: takes notes on the group’s activities; pro-poser: suggests tentative explanations to the group; skeptic: points out weaknesses in proposed explanations; moderator: leads group discussion and makes sure everyone contributes.
a. Work together to estimate the number of stars in the Milky Way from just these two facts: (1) the number of stars within 12 light-years of the Sun, which you can count in Appendix F, and (2) the total volume of the Milky Way’s disk (100,000 light-years in diameter and 1000 light-years thick), which is about 1 billion times the volume of the region of your star count.
b. Discuss how your value from part a compares to the value given in this chapter. Make a list of possible reasons why your technique may have underestimated or overestimated the actual number.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Problem 2. The redshift is defined to be the quantity
Job – Xem
Xem
where Aob and Aem are respectively the wavelengths at which radiation is observed and emitted.
1. Find the corresponding definition in terms of observed and emitted frequencies fob and fem.
2. The observed frequency of radio waves from a distant galaxy is 5 GHz. At the location of galaxy, the
frequency is 6 GHz. Calculate the redshift of the galaxy.
3. If the galaxy was 500 Mpc away from the Milky way when the radio waves were emitted. How far away
is this galaxy today?
I keep getting undefined with my equation how do I set this up?
Approximate values of length (in meters)
107
Diameter of Earth
1011
Distance from Earth to Sun
1016
Distance traveled by light in one year
1021
Diameter of the Milky Way Galaxy
1022
Distance from Earth to the nearest galaxy
1025 Distance from Earth to the edge of the known universe
Chapter 1 Solutions
Essential Cosmic Perspective
Ch. 1 - Prob. 1VSCCh. 1 - Prob. 2VSCCh. 1 - About how far away from Earth would the Sun be...Ch. 1 - Prob. 4VSCCh. 1 - Prob. 1EAPCh. 1 - Define astronomical unit and light-year.Ch. 1 - Explain the statement The farther away we look in...Ch. 1 - Prob. 4EAPCh. 1 - Prob. 5EAPCh. 1 - What do we mean when we say that the universe is...
Ch. 1 - In what sense are we “star stuff”?Ch. 1 - Use the cosmic calendar to describe how the human...Ch. 1 - Briefly explain Earth’s daily rotation and annual...Ch. 1 - Prob. 10EAPCh. 1 - Prob. 11EAPCh. 1 - Prob. 12EAPCh. 1 - Prob. 13EAPCh. 1 - Prob. 14EAPCh. 1 - Decide whether the statement makes sense (or is...Ch. 1 - Prob. 16EAPCh. 1 - Prob. 17EAPCh. 1 - Prob. 18EAPCh. 1 - Decide whether the statement makes sense (or is...Ch. 1 - Prob. 20EAPCh. 1 - Decide whether the statement makes sense (or is...Ch. 1 - Prob. 22EAPCh. 1 - Prob. 23EAPCh. 1 - An astronomical unit is (a) any planet’s average...Ch. 1 - The star Betelgeuse s about 600 light-years away....Ch. 1 - Prob. 26EAPCh. 1 - Prob. 27EAPCh. 1 - Prob. 28EAPCh. 1 - Prob. 29EAPCh. 1 - Prob. 30EAPCh. 1 - Prob. 31EAPCh. 1 - Prob. 32EAPCh. 1 - Prob. 34EAPCh. 1 - Thinking About Scale. One key to success m science...Ch. 1 - Prob. 36EAPCh. 1 - A Human Adventure. Astronomical discoveries...Ch. 1 - Prob. 38EAPCh. 1 - Group Activity: Counting the Milky Way’s Stars....Ch. 1 - Prob. 40EAPCh. 1 - Prob. 41EAPCh. 1 - Prob. 42EAPCh. 1 - Prob. 43EAPCh. 1 - Prob. 44EAPCh. 1 - Moonlight and Sunlight. How long does it take...Ch. 1 - Prob. 46EAPCh. 1 - Driving Trips. Imagine that you could drive your...Ch. 1 - Prob. 48EAPCh. 1 - Prob. 49EAPCh. 1 - Age of the Universe. Suppose we did not yet know...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- Measure the length of the meter stick using your ruler. How many ‘rulers’ is equal to the length of the meter stick?arrow_forwardUsing a single dimensional equation, estimate the number of steps it would take a person with a step length of 2.65 ft to walk from the Earth to Alpha Centauri a distance of 4.37 light-years. The speed of light is 1.86282 x 105 miles/s. Number of Steps = Enter your answer in accordance to the question statement x 1017arrow_forwardmathematician Archimedes, responding to a claim that the number of grains of sand was infinite, calculated that the number of grains of sand needed to fill the universe was on the order of 1063. Our understanding of the size of the universe has changed since then, and we now know that the observable universe alone is a sphere with a radius of 1026 m. Estimating the size of a grain of sand, A) Approximately how many grains of sand would fill the observable universe? B) How many times larger or smaller is this number than Archimedes' result?arrow_forward
- Early astronomers thought that galaxies were single stars. Why was this mistake easy to make? A. Galaxies are so far away that they look like a single star. B. Galaxies are made of stars that you can only see one at a time. C. Light from galaxies collects into a single beam. D. Earth is small and galaxies are much larger.arrow_forward1. How can physics help us gain a greater understanding of the interconnectedness of everything in the universe? 2. What is your intended career field? How might physics be used (either directly or indirectly) in your future work? 3. How can physics connect seemingly unrelated objects and phenomena?arrow_forwardHubble’s Field of View. Large telescopes often have small fields of view. For example, the Hubble Space Telescope’s (HST’s) advanced camera has a field of view that is roughly square and about 0.06° on a side. a. Calculate the angular area of the HST’s field of view in square degrees. b. The angular area of the entire sky is about 41,250 square degrees. How many pictures would the HST have to take with its camera to obtain a complete picture of the entire sky?arrow_forward
- hding Light Years 26.1 How far is it from Los Angeles to New York? Pretty far, but it can still be measured in miles or kilometers. How far is it from Earth to the Sun? It's about one hundred forty-nine million, six hundred thousand kilometers (149,600,000, or 1.496 x 10 km). Because this number is so large, and many other distances in space are even larger, scientists developed bigger units in order to measure them. An Astronomical Unit (AU) is 4:496x 108 km (the distance from Earth to the sun). This unit is usually used to measure distances within our solar system. To measure longer distances (like the distance between Earth and stars and other galaxies), the light year (ly) is used. A light year is the distance that light travels through space in one year, or 9.468 x 1012 km. 28.1 n the in tem. EXAMPLES 1. Converting light years (ly) to kilometers (km) Earth's closest star (Proxima Centauri) is about 4.22 light years away. How far is this in kilometers? Explanation/Answer: Multiply…arrow_forward1. A mole contains 6.02 * 1023 particles (atoms, molecules, etc.). If you wanted to reach an unkown planet (4.367 light-years away) by creating a strand of carbon atoms (0.3 nm diameter), how many moles of carbon would you need? (Note: 1 light-year = 9.46 * 1012 km)arrow_forwardbläi 8 :Express in scientific notation -4 4. Express 7,726,000 in scientific notation: a) with 1 Significant Figure(SFs). b) with 2 SFs. c) with 3 SFs. d) with 4 SFs 5. Express 0.0008751 in scientifie notation with : a) with 1 Significant Figure(SFs). b) with 2 SFs .c) with 3 SFs. d) with 4 SFsarrow_forward
- Astronomers use a light-year to measure distance. A light-year is the distance light travels in one year. The speed of light is approximately 300,000 km/sec.a. How long is 1 light-year in kilometers?b. The nearest star (other than the sun) is Alpha Centauri. It is 4.34 light-years from Earth. How far is that in kilometers?c. How long will it take a rocket traveling 42,000 km/hr to reach Alpha Centauri?arrow_forwardThe supermassive black hole at the center of a galaxy has a mass of 6.5 billion solar masses. If we assume that it is a Schwarzschild black hole, what is the radius of this black hole? A. 18 light hours B. 20 light hours C. 16 light hours D. 14 light hours Is the answer A? S. radius = 3 x 6.5 x 109 x 9.26567-10 = 18.1 light hours Thanks!arrow_forwardHow many galaxies like our own would it take if they were placed edge-to-edge to reach the nearest galaxy? (Hint: See Problems 11 and 12.)arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
Foundations of Astronomy (MindTap Course List)PhysicsISBN:9781337399920Author:Michael A. Seeds, Dana BackmanPublisher:Cengage Learning
Stars and Galaxies (MindTap Course List)PhysicsISBN:9781337399944Author:Michael A. SeedsPublisher:Cengage Learning
Principles of Physics: A Calculus-Based Text
Physics
ISBN:9781133104261
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning
Foundations of Astronomy (MindTap Course List)
Physics
ISBN:9781337399920
Author:Michael A. Seeds, Dana Backman
Publisher:Cengage Learning
Stars and Galaxies (MindTap Course List)
Physics
ISBN:9781337399944
Author:Michael A. Seeds
Publisher:Cengage Learning
General Relativity: The Curvature of Spacetime; Author: Professor Dave Explains;https://www.youtube.com/watch?v=R7V3koyL7Mc;License: Standard YouTube License, CC-BY