Lab 5: Planets

Credit/Permission: For text, © David Jeffery. For figures etc., as specified with the figure etc. / Only for reading and use by the instructors and students of the UNLV astronomy laboratory course.

This is a lab exercise with observations. The observations can be dropped if necessary since the lab exercise can be made sufficiently challinging without them. For the observations, see Sky map: Las Vegas: current time and weather.

Sections

  1. Objectives (AKA Purpose)
  2. Preparation
  3. Tasks and Criteria for Success
  4. Task Master
  5. Planetary Configurations
  6. Elongations and Planetary Configurations Today (IPI only)
  7. The Ptolemaic System
  8. The Copernican Revolution
  9. Kepler's 3 Laws of Planetary Motion
  10. Exoplanets (Optional at the discretion of the instructor)
  11. Planets on the Sky Today
  12. Observing the Planets Today (IPI only)
  13. Finale
  14. Post Mortem
  15. Lab Exercise
  16. Report Form: RMI Qualification: If you do NOT have a printer or do NOT want to waste paper, you will have to hand print the Report Form in sufficient detail for your own use.
  17. General Instructor Prep
  18. Instructor Notes: Access to lab instructors only.
  19. Lab Key: Access to lab instructors only.
  20. Prep Task: None.
  21. Quiz Preparation: General Instructions
  22. Prep Quizzes and Prep Quiz Keys
  23. Quiz Keys: Access to lab instructors only.

  1. Objectives (AKA Purpose)

    2. The main objective is to learn something about     planets including exoplanets.

    The main focus is on planets as astronomical objects in the old-fashioned sense: i.e., astronomical objects as seen on the sky and their orbits. We are NOT much concerned with their internal structure (e.g., with planetary geology and planetary atmospheres).

    We touch on the following topics:

    1. Planet apparent motions on the sky. Remember, in astronomy "apparent" does NOT mean false or illusionary: "apparent" means as seen from the Earth.
    2. A bit about the history of the geocentric Ptolemaic system and heliocentric solar system.
    3. Planet physical motions: i.e., their motions relative to the local inertial frame (i.e., free-fall frame) of the center of mass of the Solar System which is unrotating relative to the observable universe (or, in older astro jargon, the fixed stars).
    4. A little celestial mechanics: mostly just an intro to Kepler's 3 laws of planetary motion.
    5. The discovery and characterization of exoplanets.
    6. Weather permitting, we make observations with the telescope of the planets currently available in the sky.

  2. Preparation

    3. Do the preparation required by your lab instructor.

    1. Prep Items:

      1. Read this lab exercise itself: Lab 5: Planets.

        Some of the Tasks can be completed ahead of the lab period. Doing some of them ahead of lab period would be helpful.

      2. It is probably best to print out a copy of Report Form on the lab room printer when you get to the lab room since updates to the report forms are ongoing.

        However, you can print a copy ahead of time if you like especially if want to do some parts ahead of time. You might have to compensate for updates in this case.

        The Lab Exercise itself is NOT printed in the lab ever. That would be killing forests and the Lab Exercise is designed to be an active web document.

      3. Do the prep for quiz (if there is one) suggested by your instructor.

        General remarks about quiz prep are given at Quiz Preparation: General Instructions.

        For DavidJ's lab sections, the quiz prep is doing all the items listed here and self-testing with the Prep Quizzes and Prep Quiz Keys if they exist.

      4. This is an observing lab. So you should review Telescope Operation and List of Tricks for the Telescope as needed.

        Review the parts of the Celestron C8 telescope in the figure below (local link / general link: telescope_c8_diagram.html).

        You should also review the Observation Safety Rules.

      5. There are are many keywords that you need to know for this lab. Many of these you will learn sufficiently well by reading over the Lab Exercise itself.

        However to complement and/or supplement the reading, you should at least read the intro of a sample of the articles linked to the following keywords etc. so that you can define and/or understand some keywords etc. at the level of our class.

        A further list of keywords which you are NOT required to look at---but it would be useful to do so---is:

          Hm.

    2. Prep Items for Instructors:

      1. From the General Instructor Prep, review as needed:
        1. Basic Prep.
        2. Usual Startup Procedure.
        3. Usual Shutdown Procedure.

      2. You need to put out rulers and protractors.

      3. This is an observational lab. However, the observations are only a small part and can be omitted if the seeing is bad.

        The sky alignment on the telescopes may NOT needed if the students are only going to make quick sketches.

        However, if you are going to larger telescope magnification than provided by the 40-mm eyepieces, sky alignment is probably a good idea.

      4. The complete lab exercise may be too long for the one night.

        So section Exoplanets (Optional at the discretion of the instructor) could be omitted at the discretion of the instructor. But if observations are NOT done, it might be good. Even with if observations, it might be doable.

      5. The original Lab 5: Planets was planned to a complete lesson on planets as astronomical objects in the old-fashioned sense. That plan made the original too long. So yours truly hived off 3 tedious sections to the sequel lab exercise Lab 13: Orbits.

  3. Task Master

      4. Task Master:

        EOF

      1. Task 1: Planetary Configuration Definitions.
      2. Task 2: Planetary Configurartion Simulator Questions.
      3. Task 3: Angle Measurement with a Protractor (IPI only).
      4. Task 4: Solar System Diagrams Made Using TheSky (IPI only).
      5. Task 5: Measuring Elongations (IPI only).
      6. Task 6: The Ptolemaic System Simulator.
      7. Task 7: The Ptolemaic System and Uniqueness.
      8. Task 8: Inferior Planet Oscillation and Ptolemy.
      9. Task 9: Copernicus Questions.
      10. Task 10: Copernicus' Form of the Universe.
      11. Task 11: Scientific Theories.
      12. Task 12: The Planetary Orbit Simulator.
      13. Task 13: The Planetary Orbit Simulator and a Logarithmic Plot.
      14. Task 14: The Doppler Effect Explicated a Little.
      15. Task 15: The Exoplanet Radial Velocity Simulator. Optional at the discretion of the instructor.
      16. Task 16: The Exoplanet Transit Simulator. Optional at the discretion of the instructor.
      17. Task 17: Exoplanet Mean Orbital Radius and Year of Discovery. Optional at the discretion of the instructor.
      18. Task 18: Exoplanet Mean Orbital Radius and Orbital Period. Optional at the discretion of the instructor.
      19. Task 19: Print Sky Map and Observable Planets.
      20. Task 20: Planet Observations (IPI only).

      End of Task

  4. Planetary Configurations

    5. Before the advent of the heliocentric solar system, the actual 3-dimensional arrangements and motions in space of the planets were NOT known.

    However, there were still special APPARENT arrangements that were obviously important in determining those arrangements and motions of the planets. Wrong models were used in determining the arrangements and motions, and those arrangements and motions were determined, NOT surprisely, wrongly.

    The Ptolemaic system (AKA the geocentric Ptolemaic solar system) is the most important of those wrong models. It had a long vogue---circa 150 CE to circa 1550 or circa 1630 depending on how you count things.

    The special apparent arrangements are the planetary configurations. They and related items are part of ancient astronomy lore that everyone should know.

    Since the advent of the heliocentric solar system, the correct 3-dimensional space arrangements that create the planetary configurations have also been known.

    In this section, we consider the planetary configurations themselves and related items.

    In the 2 sections below (i.e., Determination of Orbital Periods (Optional at the discretion of the instructor) and Determination of the Mean Orbital Radii), we consider how planetary configurations are used to determine orbital periods and mean orbital radii for the planets in the Solar System.

    1. Apparent Retrograde Motion Illustrated:

      Apparent retrograde motion occurs at the time of the planetary configuration inferior conjunction for inferior planets and at the time of the planetary configuration opposition for superior planets.

      Apparent retrograde motion is explained and illustrated in the figure below (local link / general link: apparent_retrograde_motion.html).

    2. Planetary Configurations Illustrated:

      Planetary configurations are defined and the most important ones are displayed in the figure below (local link / general link: planetary_configurations.html).

    3. Task 1: Planetary Configuration Definitions:

      Complete the following short definitions in complete sentences in your own words. Read the definition or explanation from some source, think about what it means, and then formulate your own version.

      Sub Tasks:

      1. Apparent retrograde motion is:
      2. A conjunction is:
      3. The ecliptic is:
      4. Elongation is:
      5. A greatest elongation is:
      6. Inferior and superior conjunctions are:
      7. Inferior and superior planets are:
      8. An opposition is:
      9. A planetary configuration is:
      10. A quadrature is:
      11. A syzygy is:

      End of Task

    4. Task 2: Planetary Configuration Simulator Questions:

      Complete this task using the planetary configuration simulator shown in the applet figure below (local link / general link: naap_planetary_configurations.html).

      EVERYONE in the group must do this task for themselves.

      Sub Tasks:

      1. Push all the buttons to see what they do. Did you do this?     Y / N    
      2. Can you see apparent retrograde motion in the lower simulation panel?     Y / N    
      3. Can you make the simulator show the elongation angles?     Y / N    
      4. Can you make the target planet an inferior planet?     Y / N    
      5. Can you make the target planet orbit at exactly 1 AU if the observer is on Earth?     Y / N    

      End of Task

  5. Elongations and Planetary Configurations Today (IPI only)

    6. In this section, we will consider the elongations of the planets as of today and planetary configurations nearest to those elongations.

    1. Task 3: Angle Measurement with a Protractor (IPI only):

      EOF

      End of Task

    2. Task 4: Solar System Diagrams Made Using TheSky (IPI only):

      Sub Tasks:

      1. Launch TheSky (TheSky6, TheSkyX as your instructor directs).

      2. For the TheSky6, go Toolbar/File/AST105 which is probably unnecessary since AST105 should be the normal setting, but sometimes people leave TheSky6 in funny modes.

      3. Set the date to today's date & time: Go Toolbar/Data/Time.

      4. To view the Solar System appropriately, go Toolbar/View/3D Solar System Model.

        Then check out the List of Tricks for TheSky: Solar System Tricks (i.e., item 18) which tells you how to do some of the things we have to do tonight.

      5. We a view of the Solar System the north end of the ecliptic axis pointing straight out of the screen: i.e., we want the ecliptic plane (i.e., the plane of the Earth's orbit) perpendicular to the line-of-sight with eastward being counterclockwise.

        Usually, the 3D Solar System Model will just come up in this orientation. If NOT, use the Tricks (item 18) to find out how to get it.

      6. The direction of the red line is the vernal equinox which is the zero point of the right ascension (RA) in the equatorial coordinate system.

      7. Zoom in to see the inner Solar System out to Mars.

        If some inner Solar System planets are turned off, you must turn them on using the button menu with Display Explorer. See List of Tricks for TheSky: Solar System Tricks (i.e., item 18.1).

      8. Go Toolbar/File/Print Preview. Try to get the Mars orbit as large as possible and still be all visible in the Preview---you'll have to go back to TheSky to adjust the size. The larger the Mars orbit, the easier the measurements on the printout will be.

      9. Go Toolbar/File/Print Preview/Print to get a printout of the Solar System diagram. Get one printout per group to append to the favorite report form---unless your instructor asks for every group member do to a Solar System diagram.

        If you don't want to print after seeing the Preview, go Toolbar/Close.

      10. Now zoom out to show Jupiter and Saturn, click off Mercury, Venus, and Mars, but NOT Earth.

          To click off a planet, go Toolbar/View/Display Explorer/expand Solar System/expand Planets/click off planet.

      11. Get a printout of this Solar System diagram following the same procedure as for the first one.

      12. We probably won't use TheSky again tonight, but you can leave it open just in case. But when you do close TheSky, do NOT save changes.

      End of Task

    3. Task 5: Measuring Elongations (IPI only):

      Sub Tasks:

      1. If the astronomical objects are NOT named already, write in their names (i.e., label the Earth, Sun and all the shown planets) on your Solar System diagrams.

      2. Draw lines from the Earth to the Sun and all the shown planets and extend the lines well beyond the astronomical objects so that you can measure the elongations to the planets easily with a protractor.

      3. Remember elongation is measured east/west from the Earth-Sun line from 0° to 180°.

      4. Measure the elongations of the planets and put the elongation values on the diagrams showing to which angle they apply as best you can.

      5. You should attach the diagrams to the favorite report form---or, if every student printed diagrams as requested by the instructor, to every group member's report form.

      6. For today's date (see Date & Time), complete the table below (local link / general link: Table: Elongations and Nearest Planetary Configurations).

        By nearest "planetary configuration", we mean the planetary configuration nearest to today's elongation just approximately.

        You'll need to know that the greatest elongations for Mercury and Venus are, respectively, 18--28° and 45--47° (see Wikipedia: Elongation). There is a range of greatest elongations since the orbits are NOT exact circles. 

           _______________________________________________________________________________________
     Table:  Elongations and Nearest Planetary Configurations:
     For today, right now.
     _______________________________________________________________________________________

     Planet         Elongations        Nearest Planetary Configuration
                   (degrees,E/W)     (e.g., opposition, quadrature, etc.)
     _______________________________________________________________________________________

     Mercury
     Venus
     Mars
     Jupiter
     Saturn
     _______________________________________________________________________________________

      End of Task

  6. The Ptolemaic System

    7. In this section, we consider the Ptolemaic system (AKA the geocentric Ptolemaic solar system).

    1. Task 6: The Ptolemaic System Simulator:

      Complete this task using the Ptolemaic System Simulator shown in the applet figure below (local link / general link: naap_ptolemaic_system_simulator.html.html) after this task.

      EVERYONE in the group must do the task for themselves.

      Sub Tasks:

      1. Push all the buttons to see what they do. Did you do this?     Y / N    
      2. Can you see apparent retrograde motion in the 2 simulation panels for a superior planet?     Y / N    
      3. Can you make simulator show the motion of an inferior planet?     Y / N    
      4. Can you see apparent retrograde motion in the 2 simulation panels for an inferior planet?     Y / N    
      5. Can you identify your zodiac constellation by using the NAAP Applet: Seasons and the Zodiac Simulator?     Y / N    
      6. Can you change the epicycle size and the equant eccentricity, and show the Earth-Sun line and the epicycle center-planet line?     Y / N    

      End of Task

    2. Task 7: The Ptolemaic System and Uniqueness:

      The Ptolemaic system was NOT the uniquely good geocentric epicycle system---many roughly equally good geocentric epicycle systems were developed in the centuries after Ptolemy (c.100--c.170 CE).

      After reading the caption with Ptolemaic System Simulator (which is given above), discuss whether or NOT Ptolemy should have been aware of the non-uniqueness problem of geocentric epicycle systems and what might a modern scientist conclude about the geocentric epicycle theory from the non-uniqueness problem. Remember that the Ptolemaic system was worked out in great detail by Ptolemy, and so he spent a lot of time devising its particular epicycle orbits.

      Answer:

      End of Task

    3. The Full Ptolemaic System:

      The full Ptolemaic system is displayed in the cartoon below.

    4. Task 8: Inferior Planet Oscillation and Ptolemy:

      Was the fact that the inferior planets exhibit an apparent oscillation around the Sun's position on the sky (see the figure above (local link / general link: ptolemy_system.html) and the Ptolemaic System Simulator in the applet figure below (local link / general link: naap_ptolemaic_system_simulator.html.html) a clue to good old Ptolemy? Discuss. HINT: You might consider what happens in the Tychonic system and the Copernican system.

      Answer:

      End of Task

  7. The Copernican Revolution

    8. Copernican Revolution was the establishment of the heliocentric solar system as the accepted model of the Solar System.

    The Copernican Revolution was started by its eponym, Copernicus.

    1. Nicolaus Copernicus (1473--1543):

      Nicolaus Copernicus (1473--1543) was the first person to put into recorded history the heliocentric solar system as a well supported hypothesis. The qualification is "well supported hypothesis" is necessary and important.

    2. Task 9: Copernicus Questions:

      Sub Tasks:

      1. Approximately how long after Ptolemy was the lifetime of Copernicus?   _______________

      2. What is the main difference between the Ptolemaic system and the heliocentric solar system?

        Answer:

      3. Discuss why would people in the 16th century found the heliocentric solar system hard to accept. Remember, they thought motion and rest were absolutely different states and thought of the Heavens as being unchanging and eternal unlike the Earth.

        Answer:

      End of Task

    3. Task 10: Copernicus' Form of the Universe:

      Sub Tasks:

      1. Read the figure below (local link / general link: copernican_system.html) which is from Copernicus' own book on heliocentric solar system.

        Have you read it?     Y / N    

      2. Since heliocentrism gave the relative radii for the planets (which now included the Earth), the structure of the Solar System was revealed to Copernicus:

        This quote suggests that Copernicus thought that the deduced structure of the Solar System (which he thought of as being the whole universe or whole cosmos) was the main argument for heliocentrism.

        Unfortunately, Copernicus never makes that completely explicit it seems. He certainly thought of it as a major argument. Retrospectively, it clearly is the main argument.

        Now Copernicus could NOT measure absolute distances beyond the Moon. No one could until the 17th century (see Wikipedia: Astronomical unit: History).

        So how could Copernicus get the correct order and correct relative orbital radii of planets or as he put it "form of the universe". HINT: The short answer is expected.

        Answer:

      End of Task

    4. Task 11: Scientific Theories:

      From the heliocentric solar system model, Nicolaus Copernicus (1473--1543) was able to predict the mean orbital radii of the planets in their orbits around the Sun. On the other hand, from the (geocentric) Ptolemaic system, Ptolemy (c.100--c.170 CE) was NOT able to predict the locations of the planets in space, NOT even their order going outward from the Earth. He was able to make such predictions with extra hypothetical as detailed in his Planetary Hypotheses---but let's NOT consider those predictions and hypothetical since they go beyond the basic Ptolemaic system. Discuss which scientific theory is better---the heliocentric solar system model or the Ptolemaic system---from the point of view of modern science, but without knowing which is right.

      Answer:

      End of Task

  8. Kepler's 3 Laws of Planetary Motion

    9. Johannes Kepler (1571--1630) originally derived his eponymous 3 laws of planetary motion by a semi-empirical analysis of the planetary data accumulated by Tycho Brahe (1546--1601).

    The 3 laws are now understood as consequences of Newton's laws of motion and Newton's law of universal gravitation.

    1. Kepler's 3 Laws of Planetary Motion Illustrated:

      Kepler's 3 laws of planetary motion are illustrated in the 2 figures below (local link / general link: kepler_all_3_laws.html; local link / general link: kepler_2nd_law.html).

    2. Task 12: The Planetary Orbit Simulator:

      Complete this task using the planetary orbit simulator in the applet figure below (local link / general link: naap_planetary_orbit_simulator.html) after this task.

      EVERYONE in the group must do the task for themselves.

      Sub Tasks:

      1. First, read the subsection Kepler's 3 Laws of Planetary Motion Illustrated including 2 figures above (local link / general link: kepler_1st_2nd_law.html; local link / general link: kepler_2nd_law.html) illustrating Kepler's 3 laws of planetary motion.

        Have you read it?     Y / N    

      2. Push all the buttons of the planetary orbit simulator to see what they do. Did you do this?     Y / N    
      3. Start the animation. Can you find the allowed range of eccentricity?     Y / N
      4. Can you make the simulator show the planets, orbits, and orbit names out to Mars?     Y / N
      5. With parameters set for Mercury (remember to click OK) and using the Kepler's 1st law tab, can you show the empty focus, the semi-major axis, the semi-minor axis, the geometric center, and the radial lines?     Y / N
      6. Using the Kepler's 2nd law tab, can you see or hear equal areas being swept out in equal times qualitatively? There's no real right answer---just make your best judgment. If there's no speaker, you can't hear the ticking sound.     Y / N / Maybe
      7. Using the Kepler's 3rd law tab, can you make all the planets (including ex-planet Pluto) show up on the logarithmic plot? HINT: Push all the buttons.     Y / N
      8. Does the logarithmic plot show a line?     Y / N
      9. With parameters set for Mercury (remember to click OK) and and using the Newtonian features tab, can you make the velocity and acceleration vectors appear?     Y / N
      10. What is the range of Mercury's velocity?     ___________________________

      End of Task

    3. Kepler's 3rd Law:

      The Kepler's 3rd Law is somewhat explicated in the figure below (local link / general link: kepler_3rd_law.html).

    4. Power Laws and Logarithmic Plots:

      Kepler's 3rd law is an example of power law---a function relationship in which one variable varies as a power another variable.

      Power law are quite common and are often displayed on log-log plot, where they form lines.

      Say we have power law y = a*x**p, where p is a general power. If we take the logarithm of both sides we get log(y) = log(a) + p*log(x) which is a linear relation for log(y) and log(x). The slope is power p and the y-intercept is log(a).

      On a log-log plot, the axes are scaled to take the logarithm automatically.

      The tick marks are separated by powers of 10 and NOT fixed amounts.

      So one often just says "power laws are linear on log-log plots.

      See the examplein the figure below (local link / general link: log_log_plot_wik.html) of an power-law function plotted on a log-log plot.

      Note that plots where only one axis is logarithmic are called semi-log plots.

      Semi-log plots cause exponential functions to be displayed as linear.

    5. Logarithmic Plots in General:

      Collectively, log-log plots and semi-log plots are called logarithmic plots or log plots.

      Besides their use in displaying and identifying power-law functions and exponential functions, logarithmic plots have a more general use.

      The explanation of this general use is given in the figure below (local link / general link: log_log_plot_dj.html).

      Note that log plots turn up all the time in astronomy We see some examples in section Exoplanets (Optional at the discretion of the instructor) below.

    6. Task 13: The Planetary Orbit Simulator and a Logarithmic Plot:

      Sub Tasks:

      1. Read the above subsections Kepler's 3rd Law, Power Laws and Logarithmic Plots, and Logarithmic Plots in General including their embedded figures.

        Have you read them?     Y / N    

      2. Go back to the planetary orbit simulator in the applet figure above (local link / general link: naap_planetary_orbit_simulator.html). Using the Kepler's 3rd law tab, can you make all the planets (including ex-planet Pluto) show up on the logarithmic plot?     Y / N    

        What is the slope of the curve on the plot?     _________________    

      End of Task

  9. Exoplanets (Optional at the discretion of the instructor)

    10. Many astronomers, maybe most, had believed since the time of Isaac Newton (1643--1727) and even somewhat earlier that planets outside of the Solar System (i.e., exoplanets) were abundant.

    However, before 1995, there were NO confirmed exoplanets around ordinary stars (see Wikipedia: Exoplanets: Confirmed discoveries).

    This was just due to observational limitations as people had long believed.

    Now thousands of exoplanets are known---see The Extrasolar Planets Encyclopaedia for current statistics.

    Exoplanets are now known to be as common as stars to order-of-magnitude.

    There are many methods of discovering exoplanets.

    The 2 main methods Doppler spectroscopy and the transit method.

    In this section, we learn a bit about discovering exoplanets with the 2 main methods and a bit about the current statistics of exoplanets.

    1. The Doppler Effect:

      The Doppler effect/shift is the change in frequency of a wave phenomenon depending on the motion of source and receiver.

      It's a common phenomenon in everyday life for sound. For example, the pitch (which is the psychophysical response to frequency) of sirens depends on whether they are coming or going.

      In fact, the Doppler effect is rather different between mechanical waves for which a medium is needed and electromagnetic radiation (EMR) which require NO medium.

      We will NOT elaborate on mechanical waves here.

      For EMR in vacuum, only the line-of-sight relative velocity between source and receiver determines the Doppler shift.

      For positive/negative relative velocity (i.e., increaseing/decreasing separation), there is a redshift/blueshift.

      Note redshift/blueshift is astro-jargon for decreased/increased frequency which is also increased/decreased wavelength.

    2. Task 14: The Doppler Effect Explicated a Little:

      In this lab, we do NOT want to expand much on the Doppler effect/shift, but a little explication is needed to understand it for our purposes.

      Sub Tasks:

      1. Read the subsection above The Doppler Effect (local link / general link: The Doppler Effect).

        Have you read it?     Y / N    

      2. Watch all the Doppler effect videos below (local link / general link: Doppler effect videos).

        Have you watched them?     Y / N    

      End of Task

        EOF

    3. The Discovery of Exoplanets by Doppler Spectroscopy:

      Using Doppler spectroscopy, one measures the time varying Doppler shift of spectral lines in stellar spectra. They redshift, then they blueshift, then they redshift, then they blueshift ...

      The Doppler shift varies because the stars have small orbits about the centers of mass (i.e., barycenters) of their planetary systems.

      From the behavior of the Doppler shift, the orbital parameters of the stars can be determined to some degree.

      And from the orbital parameters of the stars, details about the planetary systems can be extracted, and, in particular, exoplanets can be discovered.

      Doppler spectroscopy had been in use for decades before the first exoplanet was discovered by it. It was used to study binary systems of stars where the Doppler shifts, due to mutually orbiting stars, are much larger than for a single star its planetary system.

      Making Doppler spectroscopy work in practice (for planetary systems) required the ability to detect Doppler shifts corresponding to velocities of order of magnitude 1 meter per second or less.

      This ability only developed since circa 1990.

    4. Task 15: The Exoplanet Radial Velocity Simulator:

      Complete this task using the NAAP: Exoplanet Radial Velocity Simulator shown in the figue below (local link / general link: naap_radial_velocity_simulator.html). EVERYONE in the group must do the task for themselves.

      Sub Tasks:

      2. First, read the subsection The Discovery of Exoplanets by Doppler Spectroscopy above (local link / The Discovery of Exoplanets by Doppler Spectroscopy)

        Have you read it?     Y / N    

      3. Push all the buttons of the NAAP: Exoplanet Radial Velocity Simulator to see what they do. Did you do this?     Y / N    
      4. Can you start the animation, change the animation speed, and show multiple views of the planetary system?     Y / N    
      5. What happens to the radial velocity as the inclination is increased from 0° to 90°?

        Answer:

      6. Does the radial velocity curve change with longitude of observation?     Y / N
      7. How does changing the stellar mass affect the overall radial velocity? Why does it have this effect?

        Answer:

      8. How does changing the planet mass affect the overall radial velocity? Why does it have this effect?

        Answer:

      9. How does changing the planet mean orbital radius (AKA semi-major axis) affect the overall radial velocity? Why does it have this effect?

        Answer:

      10. How does changing the planet eccentricity affect the overall radial velocity? Why does it have this effect?

        Answer:

      11. Can you show the simulated measurements?     Y / N
      12. Can you change the signal noise?     Y / N
      13. More signal noise should make the observations worse?     Y / N

      End of Task

    5. Task 16: The Exoplanet Transit Simulator:

      In the transit method for the discovery of exoplanets, one just observes the light curve of a star.

      Dips in the light curve of the right kind show that planets are transiting the star and partially eclipsing it.

      Only stars with inclination near 90° will exhibit planet transits.

      EVERYONE in the group must do this task for themselves.

      Sub Tasks:

      1. Push all the buttons on NAAP: Exoplanet Transit Simulator shown in the figure below (local link / general link: naap_exoplanet_transit_simulator.html) this task to see what they do. Did you do this?     Y / N    
      2. What happens as you change the planet mass?

        Answer:

      3. What happens as you change the planet radius?

        Answer:

      4. What happens as you change the mean orbital radius (AKA semi-major axis) with inclination NOT equal 90°?

        Answer:

      5. What happens as you change the mean orbital radius (AKA semi-major axis) with inclination equal 90°?

        Answer:

      6. What happens as you change the stellar mass?

        Answer:

      7. What happens as you change the inclination?

        Answer:

      8. Can you show the simulated measurements?     Y / N
      9. Can you change the signal noise?     Y / N
      10. More signal noise should make the observations worse?     Y / N

      End of Task

    6. Task 17: Exoplanet Mean Orbital Radius and Year of Discovery:

      Sub Tasks:

      1. Click The Extrasolar Planets Encyclopaedia: Diagrams.

      2. Select x axis semi-major axis (AKA mean orbital radius) and log scale.

      3. Select y axis year of discovery and linear scale (i.e., non-log scale).

      4. What kind of plot is shown: linear scale plot, semi-log plot, log-log plot?     ______________________________    

      5. What is the semi-major axis (AKA mean orbital radius) range for known exoplanets to order of magnitude? For example, 10**(-1) to 10**2 AU.     Answer: ______________________________

      6. Discounting the 1988 discovery (which was a tentative and only confirmed later) and 1992 discoveries (which were pulsar planets which orbit pulsars), the first exoplanet discovered was in ________________ .    

      7. Do most discovered exoplanets have mean orbital radii less than 1 AU?     Yes / No / Maybe    

      8. As Time Goes By (1931), this plot is likely to grow into a pointy-bottomed column (solid black at the center and speckly at the edges).     Yes / No / Maybe    

      End of Task

    7. Task 18: Exoplanet Mean Orbital Radius and Orbital Period:

      Sub Tasks:

      1. Click The Extrasolar Planets Encyclopaedia: Diagrams.

      2. Select x axis semi-major axis (AKA mean orbital radius) and log scale.

      3. Select y axis orbital period and log scale.

      4. What kind of plot is shown: linear scale plot, semi-log plot, log-log plot?     ______________________________    

      5. The fact that most points on the The Extrasolar Planets Encyclopaedia: Diagrams log-log plot lie nearly on a straight line agrees approximately with the dynamical Kepler's 3rd law which has the formula 
           P=[2π/(GM)**(1/2)]*R**(3/2)  ,
        where P is orbital period, M is the parent star mass (assumed much larger than the planet mass), gravitational constant G = 6.67430(15)*10**(-11) (MKS units), and R is the mean orbital radius (AKA the semi-major axis). On the log-log plot, one gets the linear relationship between logarithmic period and logarithmic radius 
           log(P)=(3/2)*log(R) + constant  .
        What is the slope of the line on a log-log plot of the dynamical Kepler's 3rd law? HINT: Reread subsection Power Laws and Logarithmic Plots above (local link / general link: Power Laws and Logarithmic Plots).     ______________________________    

      6. The set of points on the The Extrasolar Planets Encyclopaedia: Diagrams log-log plot is a band, NOT a line because 1) ________________________________ , 2) ________________________________________ .

        End of Task

  10. Planets on the Sky Today

    11. The planets in the Las Vegas sky at the current time are shown in the sky map below.

    If there are any planets in good position and weather permitting, we will observe one or more planets.

    1. Task 19: Print Sky Map and Observable Planets:

      Sub Tasks:

      1. IPI only: Print out the sky map figure below (local link / general link: sky_map_current_time_las_vegas.html) following the instructions in the figure and updating the time to your approximate observing time if necessary.

      2. IPI only: Print out one sky map per group or per group member as your instructor directs.

      3. IPI only: Did you succeed in getting a printout of the sky map?     Y / N    

      4. RMI only: Go to Sky Maps by Ordinal Date for your observing day and print out the white background sky map. You will have update the Universal Time (UT) to your observing time. For how to do this, see General Task: Naked-Eye Observations.

      5. The planets on the sky map are identified by the planet symbols---the planet symbols are elucidated in the figure below (local link / general link: sky_map_current_time_las_vegas.html)

        1. What planets can we possibly see tonight (or your observing night) because they are above the horizon NOT counting Earth?

          Answer:

        2. What planets can we see for sure tonight (or your observing night) because they are sufficiently high in the sky, they are sufficiently bright, and the weather permits?

          Answer:

        3. RMI qualification: Since you are an RMI student, you can wait a few days at least for a night with good enough weather for the observing planets.

      6. Read over the planet write-ups in the subsection Observable Planets below (local link / general link: Observable Planets) about the observable and possibly observable planets.

        Have you read them?     Y / N    

      7. RMI only: Do General Task: Naked-Eye Observations at link General Task: Naked-Eye Observations and in particular look for the observable planets that can be seen with the naked eye.

      End of Task

    2. Observable Planets:

      Here is the rundown on the planets we can observe:

      1. Mercury ☿ is an inferior planet with greatest elongation in the range 18--28° (see Wikipedia: Elongation). Thus, Mercury is always close to the Sun. If it is east of the Sun, it can visible in western sky at or just after sunset. Mercury is a naked-eye astronomical object.

        Observations for our lab are only possible for Mercury near greatest eastern elongation if the class goes out as soon or maybe earlier than the class start time 7:30 pm.

        Yours truly doesn't know if we can see the phases of Mercury with our Celestron C8 telescopes even with our highest magnification eyepiece.

      2. Venus ♀ is an inferior planet with greatest elongation in the range 45--47° (see Wikipedia: Elongation). Thus, Venus is always NOT so far from the Sun. If it is east of the Sun, it can visible in western sky at or just after sunset. Venus is a very bright naked-eye astronomical object.

        Observations for our lab are only possible for Mercury near greatest eastern elongation if the class goes out as soon or maybe earlier than the class start time 7:30 pm.

        The phases of Venus can be observed with our C8 telescopes, but you probably require a higher magnification than obtainable with our standard 40-mm eyepieces.

      3. Earth ⊕ is at nadir.

      4. Mars ♂ is a superior planet, and so can have any elongation from the Sun. Thus, if Mars is in the night sky and does NOT set too early or rise too late, it should be available for observations. Mars is a bright and reddish naked-eye astronomical object---it is the Red Planet.

        Superior planets do NOT show full planetary phases since from the Earth, since we always see at least part of the day side. In fact, the Earth is so close to the Sun relative to Jupiter and further out planets will appear virtually full all the time except to super precise measurements. Mars can appear gibbous at times (see Wikipedia: Planetary phases).

        With ideal seeing and Mars in opposition (when it is closest to the Earth), it may be possible to marginally see surface features on Mars with our C8 telescopes. But maybe light pollution rules that out. In any case, ideal seeing and opposition are relatively rare events.

        The Martian moons are probably to small to be seen with our setup under any conditions.

        Maybe long-exposure imaging could pick them out.

      5. Jupiter ♃ is a superior planet, and so can have any elongation from the Sun. Thus, if Jupiter is in the night sky and does NOT set too early or rise too late, it should be available for observations. Jupiter is a very bright naked-eye astronomical object.

        Jupiter is always full because of its remoteness from the Sun.

        The Jovian band structure and Great Red Spot (if it is on the day side of Jupiter) should be readily observable.

        The four Galilean moons should also be readily seen as bright star-like objects. They will be on a line which is rougly aligned with the Jovian band structure. One or more might be invisible if they are being eclipsed by Jupiter. One or more might be hard to see if they are transiting Jupiter.

      6. Saturn ♄ is a superior planet, and so can have any elongation from the Sun. Thus, if Saturn is in the night sky and does NOT set too early or rise too late, it should be available for observations. Saturn is a very bright naked-eye astronomical object.

        Saturn is always full because of its remoteness from the Sun.

        The Saturnian band structure may be somewhat observable.

        The rings of Saturn should be obvious.

        Saturn biggest moon Titan is probably observable. It orbits in the equatorial plane (where the Saturn's rings are too), but it might be hard to identify from background stars.

      7. Uranus ♅ (with more common symbol 4221 which in html can be fudge-up as ↑☉) is a superior planet, and so can have any elongation from the Sun. Thus, if Uranus is in the night sky and does NOT set too early or rise too late, it should be available for observations. Uranus is marginally a naked-eye astronomical object under ideal conditions---which means never in Las Vegas.

        Finding Uranus is tricky. The sky alignment on the C8 telescopes may NOT good enough to put Uranus in the field of view (FOV) finderscope. And even if it does, you still have to hunt among several possible astronomical objects.

        It's NOT impossible. It's been done.

        Uranus should appear as a bluish star Under high magnification it should look a little disky. The 9-mm eyepieces have FOV approximately 10' = 600'' and Uranus' angular diameter is 3.3--4.1'' ≅ 0.05'.

          Recall arcminutes are symbolized by the prime ' and arcseconds are symbolized by the double prime ''.

        The main thrill in seeing Uranus is just the finding of it.

      8. Neptune ♆ is a superior planet, and so can have any elongation from the Sun. Thus, if Neptune is in the night sky and does NOT set too early or rise too late, it should be available for observations. Neptune is NOT a naked-eye astronomical object.

        Finding Neptune is tricky. The sky alignment on the C8 telescopes may NOT good enough to put Uranus in the field of view (FOV) finderscope. And even if it does, you still have to hunt among several possible astronomical objects.

        It's NOT impossible. It's been done.

        Neptune should appear as a bluish star Under high magnification it should look a little disky. The 9-mm eyepieces have FOV approximately 10' = 600'' and Neptune angular diameter is 2.2-2.4'' ≅ 0.03'.

        The main thrill in seeing Neptune is just the finding of it.

      9. Ex-planet Pluto ♇; is NOT observable by us.

        Maybe long-exposure imaging with the C8 telescopes could pick out Pluto. But you would have to put the C8 telescope right on it---which is hard to do if it CANNOT be identified by visual astronomy with the C8 telescope.

  11. Observing the Planets Today (IPI only)

    12. We will go outside in a moment and observe best available planet or planets.

    1. Celestron C8 Telescope Review:

      A schematic diagram of the Celestron C8 telescope is in the figure below (local link / general link: telescope_c8_diagram.html). You should be able to name the parts.

      You will also need some specifications for the       telescope magnification and FOV for Celestron C8 telescopes. See the table below (local link / general link: telescope_c8_mag_fov_table.html).

      Also in observing the       planets, it is useful to have an idea of their angular diameters which can be compared to the FOVs specified in the table above (local link / general link: telescope_c8_mag_fov_table.html).

      The range of angular diameters in arcseconds (symbolized by the double prime '') for the planets are:

      1. Mercury 4.5--13''.
      2. Venus 9.7--66.0''.
      3. Mars 3.5--25.1''.
      4. Jupiter 29.8--50.1''.
      5. Saturn 14.5--20.1'', excluding rings.
      6. Uranus 3.3--4.4''. Seeing Uranus as disky takes a bit of confidence/imagination since it's of order 1/200th of the field of view with the 9-mm eyepiece.
      7. Neptune 2.2--2.4''.
      8. ex-planet Pluto 0.065--0.115''.

    2. Task 20: Planet Observations (IPI only):

      Sub Tasks:

      1. Read over subsection Celestron C8 Telescope Review above (local link / general link: Celestron C8 Telescope Review)

        Have you read it?     Y / N    

      2. Print out as many field of view (FOV) diagrams (see below) as your instructor requires and append them to the Report Form as your instructor directs.

        The circle on the diagram is the FOV area.

      3. Take the diagrams outside with you with something solid to hold the diagrams on when you sketch on them.

      4. Now observe the planets your instructor chooses and draw diagrams of those he/she chooses with whatever focal length eyepieces he/she chooses.

      5. Before you use an eyepiece smaller than the standard 40-mm eyepiece you have to center the planet in the FOV of standard 40-mm eyepiece. Then you switch to the smaller eyepiece.

      6. For the sketches of the FOV, sketch the planet and accompanying detail: e.g., moons, band structure, planetary rings, and stars in the FOV on the FOV diagram.

      7. Outside the circle of the FOV area, mark down the eyepiece focal length, telescope magnification, and the FOV diameter. See Table: C8 Telescope Specifications for Available Eyepieces.

      8. Also outside the circle of the FOV area, label the sky (i.e., celestial sphere) directions: north, south, east, west.

        Remember the C8 telescopes does a point inversion and the star diagonal does an plane reflection through the line perpendicular to its symmetry plane. So you can approximately figure out north, south, east, and west.

      9. Take a cell phone image of the observed planet for fun. There are no marks whether you do this or NOT.

      End of Task

  12. Finale

    13. Goodnight all.

  13. Post Mortem

    14. Post mortem comments that may often apply specifically to Lab 5: Planets:

    1. Nothing yet.