The following questions correspond to pages 17-21 in your Geotours Workbook (2nd ed.). There is no time limit once you enter this assignment, however you may only attempt the assignment once. Feel free to answer the questions first in your Geotours Workbook, and then submit your answers here!
The correct answers will be visible on the day after the due date, if you would like to revisit any of these concepts.
Google Earth – Open the 2. Exploring Geology Using Geotours > A. Earth & Sky folder.
Problem Materials – Double-click each problem to travel to the appropriate location with the prescribed perspective/zoom. Check the box next to the problem to make the placemark appear for that problem.
Earth & Sky Geotours Library – Explore additional Geotours in this folder to help answer problems. The library should appear below Problem 18 in the Earth & Sky folder.
Essentials of Geology (6th Edition (Links to an external site.) or 7th Edition (Links to an external site.)) – Consult your textbook to help answer some questions.
Questions (edited for clarity, but still correspond to the problems in your workbook; click here to download a PDF versionActions ):
Problem 1. Stellar Nursery – Pillars of Creation, Eagle Nebula. The Pillars of Creation are large, dense masses of dust and interstellar gas (mostly molecular hydrogen) that rise from the stellar nursery of the Eagle Nebula (M16). Here, dense pockets of dust and gas collapse in on themselves to form young stars. The Pillars of Creation are located about 6500 light years from Earth, and the left-most pillar has a current length of approximately 4 light years.
If a light year (the distance light travels in one year) is about 9.5 trillion km, what is the length of the left-most pillar (in km)?
Problem 2. Main Sequence Stars – Tau Ceti. If protostars accumulate sufficient mass as they develop, collapsing gas and dust may reach temperatures where hydrogen fuses into helium. Once hydrogen fusion occurs, stars become stable between the competing forces of fusion and gravity and are considered main sequence stars. Both our Sun and Tau Ceti are currently in this stage (both are considered yellow dwarf stars). For most stars, the main sequence stage lasts the longest.
From your textbook, we know that the amount of mass is inversely proportional to how fast a star burns. Which type of star will have the longer main sequence stage, and therefore, “live” the longest?
Problem 3. Red Giant Stars – Aldebaran. Eventually, the majority of hydrogen in the core of the main sequence stars is consumed, and the core collapses due to gravity. Very low-mass stars form white dwarf stars, whereas most other stars collapse and heat up until helium fusion begins. This fusion causes the star to expand outward several times larger than before, forming a red giant star (making the star cooler…Aldebaran is an example). When this happens to our Sun (in about 4.5 billion to 5 billion years), what is the most likely scenario for Earth?
Problem 4. Planetary Nebula/White Dwarf Stars – Little Ghost Nebula. Some red giant stars develop into planetary nebulas as their cores continue to contract, to increase in temperature, and to burn and vent the remaining gases into interstellar space. Eventually, the core collapses to the point where it is hot enough to ionize the vented gases, forming a relatively short-lived (~10,000-20,000 years) planetary nebula. The remaining core collapses into a white dwarf star. The vented materials from the planetary nebula play an important role in enriching the universe in elements with atomic weights less than 26 (forming the basis for carbon-based life like ourselves).
From your understanding of the assigned reading, which type of star will form a planetary nebula?
Problem 5. Nebular Supernova – Crab Nebula. Some red giant stars undergo a violent supernova explosion as opposed to forming planetary nebulas. From your understanding of the assigned reading, which type of star will form a supernova?
Problem 6. Nebular Supernova – Crab Nebula. The Crab Nebula represents a violent supernova explosion of a star (likely a third, fourth, or even later generation star). Heavy elements with atomic weights greater than 26 (and some with lesser atomic weights between oxygen and iron) were likely generated during this explosion. Which element probably formed in a supernova? Hint: refer to the periodic table in the back of your textbook (page A-2).
Problem 7. Spiral Galaxy – M51. This image is of a spiral galaxy (M51) that resembles what our Milky Way might look like if viewed from outside the galaxy. Note how the curved spiral arms develop around the more quickly rotating central cluster of stars. Looking at the spiral arms from this viewpoint, in what direction is this galaxy rotating? Hint: imagine the arms were water circulating around a whirlpool.
Problem 8. Impact Features – Moon. Apollo 11 (Problem 8a placemark) touched down in the smooth, dark Mare Tranquillitatis (Sea of Tranquility), whereas Apollo 16 (Problem 8b placemark) landed in the Descartes lunar highlands. Which region shows impact features that are larger in size and that have a higher concentration density?
Problem 9. Impact Features – Moon. Based on your answer to Question 8, which rock unit on the surface of the Moon is the youngest (and has therefore experienced fewer impacts)?
Problem 10. Impact Features – Moon. Turn off Layers > Moon Gallery > Historic Maps > Geologic Charts. Study the near side of the Moon (always faces toward Earth and has thinner crust) relative to the far side of the Moon (always faces away from Earth and has thicker crust). Which of the following best describes the nature of the dark maria?
Problem 11. Impact Features – Manicouagan Crater, Canada. Check both boxes for Problem 11 to make both placemarks appear. Use the Ruler tool to determine the present-day diameter of Manicouagan Crater (click and drag your cursor between the two placemarks. Don’t forget to clear the ruler before using it for the next problem).
Problem 12. Impact Features – Meteor Crater, AZ. Just like the previous problem, use the Ruler tool to determine the present-day diameter of Meteor Crater between the Problem 12 placemarks.
Problem 13. Impact Features – Manicouagan Crater, Canada & Meteor Crater, AZ.
Assume that a 40 m diameter meteorite created Meteor Crater. Although clearly an oversimplification, use a simple ratio between meteorite diameter and crater diameter to estimate the size of meteorite that might have created Manicouagan Crater. Hint: use the crater diameters measured for Problems 11 & 12. If you use a simple ratio, you won’t need to convert any units.
Problem 14. Impact Features – Parameters Influencing the Nature of Impact Features. On your web browser, go to the Earth Impact Effects Program website at https://impact.ese.ic.ac.uk/ImpactEarth/ImpactEffects/ (Links to an external site.)
This site estimates the consequences of an impact as a function of various parameters, including the size, velocity, and composition of the meteorite. Perform two trials to investigate the “impact” of changing projectile density by entering the following parameters:
Distance from Impact– 1000 km
Projectile Diameter– Manicouagan’s meteorite diameter (Problem 13, in m)
Projectile Density– Trial 1-ice (comet) and Trial 2-iron (some asteroids)
Impact Velocity– 20 km/s
Impact Angle– 45 degrees
Target Type– Crystalline Rock
After comparing the two trials, which of the following statements is true?
Problem 15. Solar System – Scaling. Turn on the Scaled Solar System folder by clicking the check box next to it. Double-click the folder icon to zoom out to space to see the solar system scaled from Los Angeles, CA (Sun) to New York, NY (Neptune). Click on the placemarks in this folder to see numerical information about original and/or scaled parameters, such as object radius, orbital radius (distance from the Sun), and distance between objects.
The inner planets of our solar system can be classified as rocky, terrestrial (Earth-like) planets, whereas the outer planets are considered giant, gaseous Jovian (Jupiter-like) planets. Which of the following is correct relative to the scaled solar system model shown?
Problem 16. Solar System – Scaling. Assume that you and a friend are each capable of traveling a straight-line path from Earth to Jupiter. You take a spacecraft that is capable of traveling an average speed of 70,811 km/hr (44,000 mi/hr) to the actual planet while your friend drives a vehicle at an average speed of 112.7 km/hr (70 mi/hr) along the red line of the scaled solar system. Which answer below is correct?
Hint: use the chart in the placemark to find the scaled distance from Earth to Jupiter, and the unscaled distance between their orbital radii. Review the video on unit conversions to guide your calculations.
Problem 17. Solar System – Scaling. When you look at Neptune in a telescope, you are actually looking into the past as the light has to travel from Neptune to your eyes. If the speed of light is ~300,000 km/s, how far back into the past are you looking (or put another way, how long does it take light to travel from Neptune to your eyes on Earth)? Hint: don’t forget to check the units of your final calculation!
Problem 18. Solar System – Scaling. Double-click the Problem 18 placemark to see the scaled size of Venus. Using this scaled model, what most closely approximates the area “footprint” of Venus?
Extra Credit: Use your textbook to help you answer the short answer question(s) below for additional points on this lab assignment. Your score will be unaffected if you chose not to respond, or if your response is incorrect.
EC.1 (2 pts): What is the ecliptic, and why are the orbits of the planets within the ecliptic? Why is Pluto no longer considered to be a planet?
EC.2 (1 pts): Why is the Earth spherical?
EC.3 (1 pts): Are all the stars that we see today considered to be first-generation stars? Why or why not?