Solar System Observers

1.  SUN: Sunrise, Sunset Azimuth Positions
     (not attempted)

The Sun does not follow the same path across the sky every day. In the summer at northern latitudes, the Sun is high at midday, and in the winter, it is low in the southern sky. By observing the relative positions of the Sun at dawn or dusk, one can establish that the Sun does indeed shift along the horizon. Note where the Sun sets or rises once a week for at least four weeks in the spring or fall and for 6 to 8 weeks in the summer or winter. Be certain to observe from the same position each time. Note the time, day, month and year of each observation. At what season is the shift most noticeable?

4 MOON: Maria (done-3/25)

A naked eye or binocular view of the Moon shows two distinct types of lunar surface material, the maria and the highland areas. Both areas have their own visual characteristics. The highland material reflects light to a greater degree and appears very rough in character. The various mare areas are much darker and appear smoother. Before the telescope, these dark areas were speculated to be bodies of water, hence their name mare which is sea in Latin. Observe these "seas" or maria with your telescope. What evidence do you find that these are not bodies of water? If you are interested in further study of the moon, check into the AL’s Lunar Program and the Lunar II Program.

Note: Lunar Program was completed on 6/14/2012 and the Lunar II Program was submitted on 10/15/2015. The lunar images below were taken as part of the Lunar II Program.

6 MOON: Crater Ages (done-5/25)

Twelve degrees south of the Lunar equator and about halfway from the eastern limb (Selenographic east, not east in Earth's sky) to the center of the Moon is one of the most prominent craters on the Moon. Theophilus is 100 km (62 miles) in diameter and has a terraced wall and a group of central mountains. Just to the south and west of Theophilus is another crater of equal size, Cyrillus. Remembering that the Lunar surface is constantly being eroded away by countless meteoroid impacts, which crater would you say is the oldest and why? Sunrise on Theophilus is five days after New Moon. A six or seven day old Moon should show the area well.

9 MOON: Lunar Eclipse (done-8/25)

Lunar eclipses happen twice a year and occur when at least some part of the moon moves into at least part of the Earth’s shadow. They occur only when the moon is in full phase. The type of lunar eclipse and their meanings are Penumbral Eclipse – The moon only slightly darkens. From anywhere on the moon you would see the Earth partially cover up the Sun.
• Partial Eclipse – Part of the moon becomes very dark, and part of it remains bright. If you were on the moon in the darkened part, you would see the Sun completely covered by the Earth. From the bright part of the moon, the Earth would cover only part of the Sun.
• Total Eclipse – The entire moon becomes dark. From anywhere on the moon, the Earth would completely cover the Sun. Lunar eclipses can be rated as to how dark they really get. The ratings are the Danjon Scale. • L0 – Very dark: The Moon is almost invisible, especially at mid-totality.
• L1 – Dark: Moon is dark gray or brownish, very hard to see details.
• L2 – Deep red of rust, dark center, edge is brighter.
• L3 – Brick red, rim is brighter and yellowish.
• L4 – Bright copper-red or orange, rim is bright and bluish.

Observe a lunar eclipse. Note the exact dates and times of:
start of partial eclipse, start of total eclipse, end of total eclipse, and end of partial eclipse. Also include your estimate of the rating from the Danjon Scale if it is a total eclipse

10 MERCURY (done-9/25)

As an inner planet (closer to the Sun than the Earth), the appearances of Mercury are fleeting, best seen just after sunset or just before sunrise. In compensation, this elusive planet can be seen, although sometimes with difficulty, several times a year. Mercury is never visible to the naked eye more than 28° above the horizon. Observations must therefore be accomplished during twilight when Mercury is at or near its highest elevation for that particular apparition, or appearance. The result is we must observe through the thicker portion of Earth's atmosphere. For our purposes, it will be sufficient just to locate this "Messenger of the Gods" on two different neighboring apparitions. Once in the morning sky and once in the evening sky. It may appear as a pinkish star-like object. Finding this elusive planet is its own reward. Watch for charts published in your favorite observing periodical. A pair of binoculars can be most helpful for the twilight observations, but you must wait until the Sun has sunk fully below the horizon. Record the time and date of the observations and the approximate azimuth (270°, 300°, etc.) and altitude (20°, 15°, etc.).

11 VENUS: Low Power Crescent (done-10/25)

Earth's "sister planet" will show its crescent phase in a high-quality binocular that is held perfectly still. You might try mounting it on a tripod. Consult the astronomy periodicals if you are unsure when or where to look. This observation will have to be accomplished when Venus is nearer the Earth and in its crescent phase. Galileo's observations of this the brightest of the planets provided crucial evidence for the triumph of the Copernican Sun-centered solar system. Since Venus exhibited phases it had to revolve around the Sun instead of the Earth. Can you repeat his observations? View before the sky gets too dark or Venus' brightness may obscure her phase.

12 VENUS: Daytime Observation (done-11/25)

With a polar-aligned telescope equipped with setting circles and a low-power eyepiece, Venus can be readily observed during the day. Observing during the day can be a decided advantage. The planet's brightness will be subdued enough to not dazzle the eye. The planet is also high in the sky away from the denser portion of Earth's atmosphere. CHOOSE THIS PROJECT ONLY IF YOU HAVE A TELESCOPE PROPERLY POLAR ALIGNED AND CAPABLE OF LOCATING THE PLANET WITHOUT ENDANGERING EITHER THE INSTRUMENT OR YOURSELF - USE EXTREME CAUTION - EYE DAMAGE COULD RESULT.

In your favorite astronomy periodical note the right ascension and declination of the Sun and Venus. Center the Sun in your telescope by projecting the image onto a screen or the ground. Set your setting circles to that of the Sun and turn on your drive. Now offset the appropriate amounts to arrive at the coordinates for Venus. (Make sure your focus is correct, an out-of-focus planet may be impossible to see.) You should be able to see Venus in your finder scope. An orange filter in your main eyepiece will help increase image contrast. Describe your experience.

13 VENUS: Phases --Done as part of the Galileo Observing Program

Like the Moon, Venus goes through phases. At Venus' brightest, about magnitude -4, it will be a thin crescent in your telescope. At its faintest, the entire disk will be lit. This seeming contradiction is due to the fact that the thin crescent phase happens when our sister world is nearest us. The full phase happens when she is farthest away beyond the Sun. Try to watch Venus over about a two month period, making sketches. This will give you size and phase changes over about one forth of its orbit of 224.7 days. Keep them all at the same scale and always use the same eyepiece so you can get a feel for the changes in Venus' apparent diameter. Try to make them about a week apart. Viewing while the sky is still light will help cut down glare from the planet's brilliance and also help to eliminate atmospheric distortion because the planet will be higher in the sky. If the sky is still very light an orange filter will increase the contrast between Venus and the blue background and will also cut down Venus' glare.

Note the day/date/time and seeing conditions under each sketch on an 8-1/2X11 sheet of paper.

14 MARS: Albedo Features (not attempted)

Observing the planet Mars can be either exciting and rewarding or boring and disappointing. It all depends on where the red planet is in its orbit compared with the Earth. Every 26 months Earth catches up to and passes Mars in Earth's smaller, faster orbit, and it is during these times that Mars can best be seen. This point of "catch up" is called an opposition. This is the time when Earth and Mars is on the same side of the Sun, resulting in the Sun being on the "opposite" side of the sky from us as is Mars. During this time Mars rises as the Sun sets and sets as the Sun rises, and is at its highest point in our sky at midnight. All oppositions are not created equal, however. Mar's orbit is more elliptical than our own, and these variations in distance makes Mars appear as small as 13.5 arc-seconds in diameter, or as large as 25 arc-seconds.

A few months before or after these oppositions Mars can still be observed, depending on the objective size of your telescope. Consult your favorite observing periodical for favorable Mars observing times. Many helpful hints will be given and times suggested for successful observing.

Drawing the "god of war" can be literally an illuminating experience. Sketching can help train your eye to see more detail than you would have otherwise noticed. Examine the planet for several minutes. Try an orange filter to see if that helps image contrast. Use the first accompanying circle to sketch in the major features after first locating the polar cap or possible slight phase defect. Just outlining the major features will do. Try to place them as accurately as possible. Note to the nearest minute when you have completed these steps. The first sketch should give accurate positions.

A soft pencil can be used to make a more finished looking version on the second circle. The second can be completed away from the telescope if desired, although as soon as possible while the memory is still good. It can be more "artistic", shaded to give a B&W photo appearance. If done carefully a very satisfying rendition can be had, and you will not have to be an artist to have accomplished it.

15 MARS: Retrograde Motion (not attempted)

Early naked eye observers had a problem. The planet Mars, slowly drifting west to east from night to night, when seen against the background stars, would once a year act very strangely. As Mars approached opposition it would suddenly slow down, reverse itself, drift westward for a while (retrograde motion), before again reversing to assume its normal (prograde) eastward motion. We now know that this is an illusion caused by the motion of the Earth catching up to and passing the slower Red Planet, causing Mars to appear to be moving backward. You are to plot the apparent motion of Mars through this regrograde loop. Determine what constellation Mars will be in at the time of opposition. This can be done by consulting the astronomy periodicals. Make a copy of that area out of a star atlas. For example, Will Tirion's Star Atlas 2000.0. Then watch Mars beginning about a month before opposition until a month after opposition. Plot the planet's daily position on your copy by comparing its position to the fixed stars of the constellation. After these two months you should be able to trace out Mars' retrograde motion. Fortunately for us, the Copernican Revolution solved nicely the odd behavior of Mars, and also the behavior of Jupiter and Saturn, the other classical outer planets which exhibit a lesser amount of retrograde motion.

Include Copy of Your Map of Mars Retrograde Motion.

16 CERES: Locating (done-12/25)

With the IAU’s creation of the new classification of Dwarf Planet, Ceres the Asteroid was promoted to Ceres the dwarf planet. The difference between a dwarf planet and a planet (according to IAU) is that a dwarf planet does not have enough gravity to clear other debris from its neighborhood. Locate and observe Ceres, and sketch the starfield from your observation. Note the time and date of your observation.

17 ASTEROIDS: Course Plotting (done-13/25)

Finding and following one of the small rocky planetoids that accompany the major planets around the Sun can be a most satisfying project. The small size of asteroids can make them a challenge to find, however. Although the largest, Ceres, is about 1000 kilometers (620 miles) in diameter, most range from about 100 kilometers (62 miles) to 200 k (125 miles) across, down to one kilometer (0.6 miles) or less. This means they all remain starlike even in the largest of amateur scopes. The four largest can be found in binoculars under dark skies especially at opposition when they are the brightest. All four are magnitude 8.5 or brighter. Since they are stellar in appearance their true nature can only be discerned by their movement compared to the background stars from one night to the next. Each year the daily or weekly positions for these fascinating little worlds are published in the astronomical periodicals. Using the information thus obtained, find and track an asteroid over a period of 3-5 nights. As little as three nights may be acceptable if weather is a problem. Copy an appropriate section of a star chart, preferably one that has a fairly large scale such as Will Tirion's Star Atlas 2000.0 or the Uranometria 2000.0. From your observations mark the asteroid's position as close as you can comparing it to the position of the background stars. Observe it again the following night locating and marking it again on the same star chart. Do this for three to five nights, then connect the dots showing the direction of the asteroid's movement with an arrow. Note the time and date of each asteroidal position in your notes. SEE ALSO THE NEXT PROJECT. If you are interested in further study of the asteroids, check into the AL’s Asteroid Program.

18 ASTEROIDS: Measuring their Movement (done-14/25)

Having plotted an asteroid's pathway among the background stars for at least three evenings you can now figure out its approximate hourly movement. Using a finely graded ruler such as a millimeter rule, measure the distance from the dot representing your first observation to the dot representing your second observation. If these two observations were, for example, about 24 hours apart, divide that measurement by 24 (or whatever the time interval was in hours) to find out how far the asteroid traveled in one hour. Do the same thing for each subsequent observation. How far did the asteroid move in one hour? Using the same rule, measure the width of one degree on your star chart. If, for example, your asteroid moved 2mm in one hour and if a degree on your chart is 32mm wide, your asteroid was moving one degree in 16 hours. How long did it take your asteroid to move one degree? This determination is only a rough one, of course, but nonetheless it can be fun to do, and it will give you a sense of familiarity with YOUR asteroid.

20 JUPITER: The Great Red Spot (not attempted)

Jupiter is by far the easiest planet to observe. Its giant disk offers the most detail to the amateur observer. Even at its smallest it is 30 arc-seconds in diameter, and at opposition it can be almost 50 arc-seconds, twice the size of Mars even though Jupiter is ten times further away from us! You are to time the rotation of the Red Spot across the center of the disk of the planet Jupiter. In the "Calendar Notes" column in Sky and Telescope magazine the dates and times are given when this famous feature on Jupiter is due to cross the Central Meridian of the planet. The Central Meridian (CM) is a line drawn from the planet's north pole to its south pole dividing the great globe into two equal eastern and western sections. This project will require three timings. The first is the time at which the leading edge of the spot crosses the CM. The second is the time at which the spot appears centered exactly on the CM. The third is the time at which the trailing edge of the spot reached the CM. Use the S&T column to guide your observing sessions. If you can only make one timing, make it number two, the central transit time. Access to a WWV time signal is preferable but if this is impossible, the observation is still acceptable. State if WWV or another standard time source was used in making your report. Do not forget to convert to Universal Time. During the past few years the Great Red Spot has been very pale and should perhaps be known as the Great Pale Salmon Colored Spot!

21 JUPITER: --Done as part of the Galileo Observing Program

Ever since Galileo it has been noted that the planet Jupiter and its four brightest and largest satellites form a kind of miniature solar system with a speeded up time scale. This magnification of time scale makes the system especially interesting to those who study potential changes in orbital mechanics. We have observed data on Jupiter's moons going back about 300 years. This consists of the recorded times when a satellite disappeared upon entering Jupiter's shadow or reappeared upon exiting from it. Studying this data makes it possible to determine if Jupiter's satellite's orbits, and by inference, planetary orbits, change over periods of time. These eclipses are spectacular phenomena to watch in a small telescope. Since timings require a WWV time signal receiver. For this exercise, we will only ask you to sketch the satellite positions on this page for six consecutive nights identifying each satellite in your sketches. Include a copy of them in your report. As much as possible, try not to skip more than one night between consecutive viewings. The "Jupiter's Moons" chart in the Almanac section of astronomy magazines each month will help you to identify the individual moons.

To show the East-West direction of your sketches show with an arrow the direction of drift in your field of view without a drive running.

22 JUPITER: The Cloud Belts --Done as part of the Galileo Observing Program

The first thing that comes to a person's attention when looking at the disk of the great planet Jupiter are the striated clouds of its turbulent atmosphere. Fascinating and compelling, even a modest telescope reveals a good amount of detail but always leaves you yearning for more. Through the years a system of nomenclature has been applied to the alternating dark and light areas called belts and zones, respectively. Coupled with the giant's fast rate of spin (Jupiter's bulk rotates once in a little under ten hours) even the casual observer can notice something new. Below is a detailed list of the main cloud bands. Not all are always present all of the time. Jupiter's dynamics are too complicated for that. How many can you see? Make your own sketch and label those parts that seem to match up with the accompanying diagram. Include a copy of your sketch in your report.

Jupiter Nomenclature

Do not worry about a lot of detail. In fact Jupiter rotates so rapidly that features may move if you take too long to work on details. NOTE: Your telescope may show Jupiter inverted.

To show the East-West direction of your sketch show with an arrow the direction of drift in your field of view without a drive running.

24 JUPITER: Satellite Shadow Transits (done-17/25)

Shadow transits occur quite often and are a phenomenon that can easily be seen by the amateur. The shadows cast by the Galilean satellites are seen as tiny black dots slowly proceeding across the cloud tops of the giant planet.

Your task is to determine which of the four largest Jovian moons is casting the shadow. First, you need to know if Jupiter is approaching its yearly opposition or if opposition has already passed. If Jupiter is moving toward its opposition then the shadow precedes the satellite. The moon's shadow will fall on the planet while the moon itself is still nearing the planet's limb. If opposition has passed, the moon will cross the planet's disc first, followed by its shadow. By consulting a Galilean Satellite Chart in an astronomy periodical you should be able to determine which satellite is casting the shadow. Which satellite was it?

25 JUPITER: Satellite Transits (done-18/25)

Watching the Galilean Moons transit the disk of Jupiter is considerably more of a challenge than watching their corresponding shadows. The tiny little disks are similar in color to their parent planet so the satellite quickly gets lost from view in its frontal passage. The satellites can often be seen under the right conditions with larger apertures, for a few minutes, while still on the edge of Jupiter's limb. The limb tends to be slightly darker than the face of the planet itself. The contrast between the two helps the satellite to show up. The slow ingress or egress varies with each satellite. Io and Europa, being inner satellites, take only about two and a half minutes to ease onto or off of Jupiter's limb. Ganymede moves much more slowly, taking seven minutes, and Callisto crawls across the limb for nine minutes. If you are able to detect these ingresses or egresses, time them with a stopwatch and compare the times with those just given. An alternative project would be to time the ingress or egress of one of the satellites into or out of Jupiter's shadow. What satellite did you time?

26 JUPITER: --Done as part of the Binocular Solar System Observing Program

Eclipses of the Galilean satellites occur as they move into or out of Jupiter’s shadow. This is different than an Occultation (see next requirement). Time the disappearance or reappearance of one of these satellites by using a radio tuned to the WWV National Time Standards signal out of Ft. Collins, Colorado. Then compare it to the time printed in the astronomy periodicals. Note the time when the satellite completely disappears into or reappears from behind Jupiter's shadow. Timing a reappearance is much more difficult since you do not know precisely when or where it will appear. Note the name of the moon that you observed.

29 SATURN: The Cassini Division (done-20/25)

Within the three major rings that can be seen through the amateur telescope is the prominent gap known as the Cassini Division. It separates the "B" Ring, the brightest ring, from the "A" Ring and appears as a fine black line circling the planet. It is most easily seen on the two protrusions of the rings on either side of the planet known as ansae.

The axial tilt of Saturn and the inclination of Saturn's orbit compared with the Earth's, combine to cause the plane of Saturn's rings to change their tilt. About every 7.25 years the rings go from edge-on to fully open. Your ability to see the Cassini Division will vary depending on how "open" or "edge-on" the rings are. Seeing and aperture size will also affect your ability.

Describe your view of Cassini's Division. Can you see it? Can you barely see it or does it "jump out at you?" How complete a circle of the rings can you detect?

30 SATURN: Disk Markings (done-21/25)

At first glance the face of Saturn's disk seems rather boring, a bland creamy-yellow ball. Less than half the apparent diameter of Jupiter with proportionately duller markings, Saturn requires diligent study and a tranquil night of seeing. The greater your observing skill or equipment, the more subtle the details you will see.

You should be able to tell that one hemisphere is decidedly darker than the other Can you tell which one? Be certain you know if your telescope shows an upright or an inverted image. Belts, zones, and spots similar to Jupiter's can sometimes be glimpsed through the planet's top layer of obscuring haze. They are subtle. What do you see? Record your impressions.

31 SATURN: The Satellites (done-22/25)

Of all the satellites of Saturn, only six of them can be seen in telescopes with moderate sized apertures. How many can you spot?

Mag Orbital Period (Earth Days) Recommended

• Enceladus 11.8 1.37 8-inch

• Tethys 10.3 1.9 6-inch

• Dione 1 0.4 2.7 6-inch

• Rhea 9.7 4.5 3-inch

• Titan 8.4 15.9 2-inch

• Iapetus 10.2-11.9 79.3 8-inch

How many satellites you will be able to see will depend a great deal on atmospheric conditions. For example, I have seen all of them in a six-inch. In contrast with Jupiter, where all four moons' orbital plane is nearly a straight line from Earth's viewpoint, Saturn's equatorial plane is considerably more tilted. This means that the orbits of the satellites can vary from a nearly straight line configuration to that of nearly a 30° ellipse depending on where Saturn and Earth are located in their orbits. This inclination changes at about a 15-year interval. Finder charts can be found in astronomy periodicals that will help you determine which of the Saturnian satellites you are seeing.

A note on Iapetus. The magnitude variation can be explained by the fact that it has two vastly different hemispheres. One reflects light almost two magnitudes brighter than the other. What satellites did you see?

32 URANUS: Locating (Done-23/25)

In 1781 the first non-classical planet was discovered by amateur astronomer William Herschel. The discovery changed Herschel's life forever and was a blow to astrologers who by their "craft" had no inkling that a seventh planet existed. Actually the planet had been seen and charted years before on no fewer than seventeen different occasions. Uranus is visible to the dark adapted naked eye under good skies. But the astronomers simply added it to their charts just like any other sixth-magnitude star. It was Herschel who finally had enough resolving power and the observer's eye who could tell it had, in fact, a tiny disk, and was not a simple star-like point. He first suspected the tiny object to be a distant comet and took a series of measurements of its position. It was somewhat later that he realized its true nature.

It is much easier today for you and I. The 3.8 arc-second greenish disk shines at a magnitude of 5.7 and can be readily found using locator charts published in the astronomical periodicals. Give a verbal description of your eyepiece impression.

33 NEPTUNE: Locating (done--24/25)

Although similar in size and appearance as Uranus, Neptune's distance averages over one billion miles further from the Earth. This great distance makes its apparent diameter about 2-1/2 arc-seconds, a little over half the size of Uranus.

The 7.6th magnitude bluish dot will probably look stellar, for its tiny disk is near the resolving limit of most amateur telescopes. Consult your favorite astronomy periodical to find out where it is currently located. Write a verbal description of your impression.

34 PLUTO: Locating (done-25/25)

When the IAU made their decision to include a new class of objects in the Solar System called Dwarf Planets, Pluto was demoted from Planet to Dwarf Planet. Besides Ceres, it is the only Dwarf Planet that may be visible in a backyard telescope, but at magnitude 13.8 it may require a large telescope. The third Dwarf Planet, as of mid-2008 is Eris. It is located far beyond Pluto and far beyond the capabilities of backyard telescopes. Locate and observe Pluto, and sketch the starfield from your observation. Note the time and date of your observation