Scoutles.com – In learning about astronomy merit badge, you will study how activities in space affect your own planet. Your daily schedule day time and nighttime are dictated by Earth’s position as it rotates on its axis.
Earth’s orbit around the Sun takes a year and gives us the changing seasons. The Sun’s energy affects the weather, and the gravitational pull between Earth and the Moon creates and controls ocean tides.
Let’s get started
Astronomy Merit Badge Requirements
- Do the following:
- Explain to your counselor the most likely hazards you may encounter while participating in astronomy activities, and what you should do to anticipate, help prevent, mitigate, and respond to these hazards.
- Explain first aid for injuries or illnesses such as heat and cold reactions, dehydration, bites and stings, and damage to your eyes that could occur during observation.
- Describe the proper clothing and other precautions for safely making observations at night and in cold weather. Then explain how to safely observe the Sun, objects near the Sun, and the Moon.
- Explain what light pollution is and how it and air pollution affect astronomy.
- With the aid of diagrams (or real telescopes if available), do each of the following:
- Explain why binoculars and telescopes are important astronomical tools. Demonstrate or explain how these tools are used.
- Describe the similarities and differences of several types of astronomical telescopes, including at least one that observes light beyond the visible part of the spectrum (i.e., radio, X-ray, ultraviolet, or infrared).
- Explain the purposes of at least three instruments used with astronomical telescopes.
- Describe the proper care and storage of telescopes and binoculars both at home and in the field.
- Do the following:
- Identify in the sky at least 10 constellations, at least four of which are in the zodiac.
- Identify in the sky at least eight conspicuous stars, five of which are of magnitude 1 or brighter.
- Make two sketches of the Big Dipper. In one sketch, show the Big Dipper’s orientation in the early evening sky. In another sketch, show its position several hours later. In both sketches, show the North Star and the horizon. Record the date and time each sketch was made.
- Explain what we see when we look at the Milky Way.
- Do the following:
- List the names of the five most visible planets. Explain which ones can appear in phases similar to lunar phases and which ones cannot, and explain why.
- Using the internet (with your parent’s permission) and other resources, find out when each of the five most visible planets that you identified in requirement 5a will be observable in the evening sky during the next 12 months, then compile this information in the form of a chart or table.
- Describe the motion of the planets across the sky.
- Observe a planet and describe what you saw.
- Do the following:
- Sketch the face of the Moon and indicate at least five seas and five craters. Label these landmarks.
- Sketch the phase and position of the Moon, at the same hour and place, for four nights within a one-week period. Include landmarks on the horizon such as hills, trees, and buildings. Explain the changes you observe.
- List the factors that keep the Moon in orbit around Earth.
- With the aid of diagrams, explain the relative positions of the Sun, Earth, and the Moon at the times of lunar and solar eclipses, and at the times of new, first-quarter, full, and last-quarter phases of the Moon.
- Do the following:
- Describe the composition of the Sun, its relationship to other stars, and some effects of its radiation on Earth’s weather and communications.
- Describe the composition of the Sun, its relationship to other stars, and some effects of its radiation on Earth’s weather and communications.
- Identify at least one red star, one blue star, and one yellow star (other than the Sun). Explain the meaning of these colors.
- With your counselor’s approval and guidance, do ONE of the following:
- Visit a planetarium or astronomical observatory. Submit a written report, a scrapbook, or a video presentation afterward to your counselor that includes the following information:
- Activities occurring there.
- Exhibits and displays you saw.
- Telescopes and other instruments being used.
- Celestial objects you observed.
- Plan and participate in a three-hour observation session that includes using binoculars or a telescope. List the celestial objects you want to observe and find each on a star chart or in a guidebook. Prepare a log or notebook. Discuss with your counselor what you hope to observe prior to your observation session. Review your log or notebook with your counselor afterward.
- Plan and host a star party for your Scout troop or other groups such as your class at school. Use binoculars or a telescope to show and explain celestial objects to the group.
- Help an astronomy club in your community hold a star party that is open to the public.
- Personally take a series of photographs or digital images of the movement of the Moon, a planet, an asteroid, meteor, or a comet. In your visual display, label each image and include the date and time it was taken. Show all positions on a star chart or map. Show your display at school or at a troop meeting. Explain the changes you observed.
- Visit a planetarium or astronomical observatory. Submit a written report, a scrapbook, or a video presentation afterward to your counselor that includes the following information:
- Find out about three career opportunities in astronomy. Pick one and find out the education, training, and experience required for this profession. Discuss this with your counselor, and explain why this profession might interest you.
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Getting Ready to Observe
Know how to protect yourself before you go out in search of the next great astronomical discovery.
When you go stargazing, dress appropriately for the weather hot or cold. To help protect yourself against bites and stings when you go outside, wear clothes that cover all exposed skin, and be sure to button and tuck them in.
Wear shoes or boots, not sandals and socks. Insect repellent sprayed on your body, clothing, and shoes provides added protection.
Here’s information that can help you to answer requirement 1 of the astronomy merit badge.
1. Moving in the Dark
During the day before a stargazing outing, survey the area where you will be observing. Look for drop-offs, holes, crevices, or other objects like large rocks or tree roots that you might not see at night.
Take care to avoid the hazards when you return at night to observe. Bring red-filtered flashlights to illuminate the area.
It takes about 30 minutes for the human eye to adjust to the darkness. To help preserve your night vision, use a red filter with your flashlight. Simply secure a piece of red cellophane over an ordinary flashlight.
2. Protect Your Eyes
Never stare directly at or near the Sun, even for a few moments. never look at the Sun through binoculars or a telescope unless your equipment has the proper solar filters.
Looking directly at the Sun even while wearing sunglasses can cause permanent blindness or other damage to your eyes that might not be immediately noticeable.
The safest way to observe the Sun is indirectly by projection, which is explained in the chapter called “The Moon Our Nearest Neighbor.” Projection is the recommended method for safely viewing the sun.
In any case, always do so only under the supervision of a knowledgeable adult.
Observing objects near the sun
Mercury, the planet nearest the Sun, always lies close to the Sun in the sky. Look for Mercury only when the Sun’s disk is entirely below the horizon.
Don’t risk getting the Sun in the view. This could cause permanent eye damage or blindness.
3. Heat Exhaustion and Heatstroke
Heat exhaustion occurs when the body overheats because its cooling methods fail. Watch for these signs: body temperature between 98.6 and 102 degrees, skin pale, clammy, and sweaty, nausea, dizziness, and fainting, pronounced weakness and tiredness, headache, muscle cramps.
To treat heat exhaustion, have the victim lie down in a cool spot with the feet raised. Loosen the clothing. Apply cool, damp cloths to the skin or use a fan. Have the victim sip water.
Heatstroke (sunstroke) is life-threatening because the body’s heat control system has been overworked and overwhelmed, resulting in its failure.
Signs include a body temperature above 102 degrees, red, hot, and dry skin, extremely rapid pulse, confusion or disorientation, fainting or unconsciousness, convulsions.
Cool the victim immediately. Place the victim in a cool spot face-up with head and shoulders raised. Remove outer clothing, sponge the bare skin with cold water, and soak underclothing with cool water.
Apply cold packs, use a fan, or place the victim in a tub of cold water. Dry the skin after the body temperature drops to 101 degrees. Obtain medical help immediately.
4. Sunburn
Sun exposure can catch you by surprise when you are outside, preoccupied with setting up your equipment, or viewing a solar eclipse.
Wear loose-fitting clothing that completely covers the arms and legs and a brimmed hat.
Apply sunscreen with a sun protection factor (SPF) of at least 15 to exposed skin. Don’t forget your ears and the back of your neck. Reapply sunscreen often and as needed.
Hypothermia occurs when the body’s core temperature drops so low that it is no longer able to keep warm.
The key to preventing hypothermia is to keep warm and stay dry, and if you will be outside for extended periods eat plenty of energy foods (nuts, dried fruits, peanut butter).
Don’t push yourself to a dangerous point of fatigue.
A person in the early stages of hypothermia may be shivering. As the victim gets colder, the shivering will stop. Other symptoms may include irritability, sleepiness, incoherence, disorientation, and the inability to reason or think clearly.
Immediately prevent further heat loss. Move the victim to a shelter, remove damp clothing, and warm the person with blankets until body temperature returns to normal.
Cover the head with a warm hat or other covering, and offer hot drinks. If the condition progresses, actively warm the victim’s body. Place the victim into a sleeping bag with one or two other people.
All should be stripped of most clothing so that skin-to-skin contact can hasten the warming and perhaps save a life. Severe hypothermia requires immediate medical attention.
6. Dehydration
Dehydration is caused by lack of water in the body. A person who gives off more water than consumed can become dehydrated in hot or cold weather.
Astronomical observers should stay well hydrated while in the outdoors. Do not wait to drink until you feel thirsty.
The following information can help in answering Requirement 3 of the Astronomy Merit Badge.
Astronomical Tools
You can observe objects in the night sky with your unaided eye. However, with binoculars or a telescope, the images you see will appear brighter and larger.
The following are tools and instruments used in astronomy merit badge.
1. Binoculars
Binoculars are perfect for stargazing. They collect more light than the human eye, so you can see 50 times more stars with 10×50 binoculars. They also improve the clarity and intensify the colors of the stars you see.
Unlike a telescope, binoculars allow you to use both eyes to view. Binoculars show an image the right way up, whereas telescopes show objects upside down.
Binoculars are easy to transport and less expensive than many telescopes.
Because of their wide field of view, binoculars are perfect for studying the surface of the Moon, scanning the Milky Way, spotting Jupiter’s large moons, and viewing star clusters.
Some giant binoculars have lenses of 70 millimeters or more and magnifications of 15x to 20x. Wider lenses allow you to see more stars, but these giant binoculars are so heavy that they must be mounted on a tripod , like a telescope for viewing.
2. Telescopes
Like binoculars, telescopes gather more light than the human eye. The two main types of optical telescopes those that collect visible light are refracting and reflecting, with a third type, the catadioptric, that combines features of the refractor and the reflector.
Refracting telescopes use a system of lenses. At the large end of the telescope, the objective or front lens collects and focuses light. The eyepiece, the smaller lens you look through, is at the other end. Refracting telescopes produce sharp images.
In the reflecting telescope, a concave (bowl-shaped) mirror at the base of an open tube collects and reflects light to a second, smaller mirror near the top of the tube.
The eyepiece magnifies the image that the mirrors have formed. The reflector is the most common type of telescope and a popular choice for backyard astronomers.
The catadioptric telescope also called a refracting-reflecting telescope, combines a large front lens with two mirrors. It has a short, enclosed tube and is often portable.
For more information about different types of telescope, you can read in this link.
3. Radio and X-Ray Telescopes
Radio telescopes pick up images that astronomers would not be able to see otherwise. Radio waves from space enter the telescope’s large bowl-shaped (dish) antenna, and the radio receiver picks up the signals.
A computer converts the signals into images. Radio signals reveal details, including temperature and composition, of objects in space that give off radio waves.
X-ray telescopes help scientists determine the galaxy’s hot spots. Cosmic X-rays the invisible radiation emitted from very hot objects captured by telescopes above Earth’s atmosphere help scientists study dying stars, colliding galaxies, and quasars, extremely bright starlike objects that give off enormous amounts of energy.
NASA’s most sensitive X-ray telescope, the Chandra X-ray Observatory, captures X-rays from the edge of the observable universe.
Also Read : Aviation Merit Badge
Care of Binoculars and Telescopes
Following the manufacturer’s recommendations and a few simple tips will help you keep your viewing equipment in good shape for many years.
- Handle binoculars and telescopes carefully and with respect. Repeated bumping, shaking, and dropping can cause the lenses to break or become misaligned.
- Keep your equipment clean. Keep lenses free from dirt, debris, fingerprints, and moisture. Use a cloth (such as a microfiber cloth) and cleaner made especially for lenses. Apply cleaner very sparingly to the cloth and never directly to the lenses.
- Keep dust from building up on lenses. Aside from normal cleaning, you may use a very soft brush (such as camel’s hair), or compressed air if you take some precautions. You want to avoid any contact with the lenses and any liquid from the can. Before use, avoid shaking the can. Always hold the can upright and never tilted or directly overhead while spraying. Use a few short (a second or two) bursts of air, stop immediately if the can starts to feel cold.
- Keep the water away. Protect equipment from the elements such as rain, snow, and in particular salt water, which is corrosive. Repeated use in high humidity will also have a negative effect on the equipment.
- In the field, use and wear the strap that comes with your binoculars to keep them safely around your neck.
- Store binoculars and telescopes in a cool (not cold), dry place, away from humidity and extreme temperatures, which will have a negative effect on the lens coatings and housing. Use the storage or carrying case and rubber eyecups (in the “up” position) that came with your equipment.
Here’s information that can help you to answer requirement 4 of the astronomy merit badge.
Stars and Constellations
People have always enjoyed studying the stars. To help them keep track of the stars, ancient Greeks creatively drew imaginary lines between stars to form images of mythological characters or other familiar creatures.
These star groups are known as constellations. Today, astronomers recognize 88 constellations.
1. Year-Round Constellations
Some constellations are visible at any time of the year. These constellations are known as circumpolar because they never set below the horizon. As Earth rotates on its axis, the stars seem to circle a point called the celestial north pole.
The north pole itself points to Polaris, or the North Star. Finding Polaris will be a big help in locating the four main circumpolar constellations.
| Ursa major. The Big Dipper is part of Ursa Major (the Great Bear), a constellation that includes a few less-visible stars. The outer stars on the bowl of the Big Dipper always point to Polaris. Every six hours, the Big Dipper appears to have moved a quarter of the way around Polaris. |
| Ursa minor. The Little Dipper, with stars fainter than the Big Dipper, is part of the constellation Ursa Minor, or the Little Bear. Polaris is the end of the Little Dipper’s handle. |
| Cassiopeia. If you follow the line from the middle star of the Big Dipper’s handle through Polaris, you will find Cassiopeia. Its five main stars form an M when they’re above the North Star and a W when they are below it. |
| Draco. Draco, the dragon, winds around Polaris between the Big and Little Dippers. None of its more than 80 visible stars is very bright; the four stars that form the dragon’s head are easiest to see. |
2. Seasonal Constellations
Some constellations are visible in the night sky only at certain times of the year. Twelve seasonal constellations known as zodiacal constellations are centered on the ecliptic, the path that the Sun, the Moon, and the planets all appear to follow through the sky.
The zodiacal constellations you can see at night: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricornus, Aquarius, and Pisces change as Earth follows its yearly path around the Sun.
Spring Constellations
| Leo. You can see Leo, the Lion, from January through June. From the two stars of the Big Dipper’s bowl that are not used to point toward Polaris, follow with your eye a line straight down to Leo’s brightest star, Regulus. |
| Virgo. Virgo, the Virgin, is the largest constellation and is visible from April through July. If you look from the handle of the Big Dipper through Arcturus (a bright star in the constellation Boötes), you will see another bright star. This is Spica, the bottom of Virgo’s Y shape. |
| Libra. Libra, the Balance Scale, is a late-spring constellation with four fairly dim stars. It is one of the most difficult zodiacal star patterns to spot. Look between Spica and the southeastern horizon. |
| Cancer. Cancer, the Crab, is visible from January to May, but it is the faintest constellation in the zodiac. To find it, follow a line from Leo’s Regulus to the Gemini constellation (a winter constellation described below). Cancer is between Leo and Gemini. |
Summer Constellations
| Lyra. You can see Lyra, the Lyre, from May through November. In late summer at about 10 p.m., if you look straight up, you may see a very bright blue-white star. This star, Vega, is Lyra’s brightest star. |
| Cygnus. Often called the Northern Cross, Cygnus the Swan is visible from June through November. Follow a line from Vega slightly east to another star, Deneb, that is almost as bright. Deneb is Cygnus’s brightest star. |
| Aquila. The somewhat triangular grouping in the summer sky south of Lyra and Cygnus is Aquila, the Eagle. Its brightest star is Altair, which forms the Summer Triangle with Deneb and Vega. |
| Scorpius. In July and August, you can see Scorpius, the Scorpion, very close to the southern horizon. Its brightest star is Antares, a red supergiant star near the scorpion’s head. |
| Sagittarius. In July and August, you can see Sagittarius, the Archer, just east of Scorpius. Its main stars form a pattern that resembles a teapot. When you look at Sagittarius, you’re looking toward the center of the Milky Way galaxy. Scorpius and Sagittarius may be difficult to view if you live in the North. |
Autumn Constellations
| Pegasus. Pegasus, the Flying Horse, is best seen from August through October, southeast of Cygnus. Part of the constellation is known as the Great Square, an easy shape to recognize. |
| Andromeda. Pegasus shares one of its stars with Andromeda, which is visible from September to January. Look eastward from the Great Square of Pegasus. The Andromeda galaxy the most distant object visible to the naked eye is visible on clear nights as a faint, misty spot in the Andromeda constellation. |
| Perseus. You can see Perseus in the autumn and winter, east of Andromeda. It lies between the constellations of Auriga (described below) and Cassiopeia. Perseus contains the double star Algol. As the stars of Algol pass in front of each other, Algol appears alternately fainter and brighter. |
| Aries. Three fairly bright stars make up the main part of Aries, the Ram. It appears south of Andromeda from October through March. |
| Pisces. The main part of Pisces, the Fishes, is a string of stars below Andromeda and Pegasus. Pisces appears in the sky from October to December, but it is faint and can be hard to find. |
| Capricornus. Look straight down from the star Altair in Aquila. Capricornus, the Sea Goat, is a faint constellation, but when visibility is good you can see it from August through October. |
| Aquarius. On dark, clear nights from August through October, you may be able to see Aquarius, the Water Bearer, south of Pegasus. One end of Aquarius stretches above Capricornus and the other is below the Circlet of Pisces. |
Winter Constellations
| Orion. Orion, the Hunter, usually is easy to find from October through April. It is large and distinctive with two very bright stars the reddish-orange giant Betelgeuse and bluish-white Rigel as well as five other bright stars and several less visible ones. The Orion Nebula, a cloud of dust and gas several lightyears across, is visible to the naked eye as a fuzzy patch just below Orion’s belt. |
| Canis major. Southeast of Orion is Canis Major, the Great Dog, which you can see from December through April. Sirius, the night sky’s brightest star, is a part of Canis Major. Orion’s three belt stars point downward toward Sirius. |
| Gemini. From December through May you can see Gemini, the Twins, northeast of Orion. Two bright stars, Castor and Pollux, are the heads of the Gemini twins. |
| Auriga. Visible from November through April, Auriga, the Charioteer, is north of Orion. Capella, a double star in Auriga, is one of the brightest lights in the sky. |
| Taurus. Orion’s belt stars point up toward Aldebaran, a bright orange-red star. Aldebaran is the eye of Taurus the Bull, a constellation you can see from November through March. |
3. The Brightest Stars
Another word astronomers use to describe a star’s brightness is magnitude.
- Absolute magnitude refers to a star’s true brightness that is, the brightness if all-stars were viewed from the same distance.
- Apparent magnitude means the brightness of a star as we see it from Earth. Astronomers give a star a number to refer to this magnitude. The lower the magnitude number, the brighter the star. Stars that are brighter than a magnitude 1 have a zero or negative number. The unaided human eye can see stars with a magnitude number as high as 6.
Listed here are some of the brightest stars in the sky, the constellations where they are found, and their apparent magnitude.
| Star | Constellation | Magnitude |
|---|---|---|
| Sirius | CanisMajor | -1.46 |
| Arcturus | Boötes | -0.04 |
| Vega | Lyra | 0.03 |
| Capella | Auriga | 0.08 |
| Rigel | Orion | 0.12 |
| Procyon | CanisMinor | 0.38 |
| Betelgeuse | Orion | 0.5 |
| Altair | Aquila | 0.77 |
| Aldebaran | Taurus | 0.85 |
| Antares | Scorpius | 0.96 |
| Spica | Virgo | 0.98 |
| Pollux | Gemini | 1.14 |
| Deneb | Cygnus | 1.25 |
4. The Milky Way
When we look at the Milky Way in the night sky, we see our own galaxy. Apart from other galaxies, everything we see in the night sky the stars, star clusters, nebulae, the Sun, the Moon, and the planets is part of the Milky Way.
Just as its name implies, it appears as a whitish band of light. For observers in the northern hemisphere, it is brightest in the summer months in the constellations Aquila and Cygnus.
The Milky Way is our home galaxy, a gigantic disk of hundreds of billions of stars and vast quantities of dust and gas. It is about 100,000 light-years across and some 10,000 light-years thick at its center.
Stars, dust, and gases fan out from the hub of this huge whirling disk in long, curving arms that make a spiral or pinwheel shape. Our solar system is about halfway out from the center on one of the arms.
The Milky Way appears to be an average spiral galaxy.
You can see another galaxy with the unaided eye on a clear night in the fall the Andromeda Galaxy. It also is the most distant object you can see with the naked eye. It appears as a misty patch of light in the constellation of Andromeda.
Astronomers call the Andromeda Galaxy “M31” and place it at about 2.4 million light-years from Earth. M31 appears to be half again as big as our galaxy 150,000 light-years across.
The Planets and Our Solar System
The planets of our solar system travel around the Sun, each in its own orbit. The four planets closest to the Sun Mercury, Venus, Earth, and Mars are called the terrestrial (earthlike) planets because they have solid, rocky surfaces.
The four large planets beyond the orbit of Mars Jupiter, Saturn, Uranus, and Neptune are the gas giants, made mostly of hydrogen and helium, probably with no solid surfaces.
1. Mercury
Sercury is the small, rocky planet nearest the Sun. It completes a trip around the Sun every 88 Earth-days, speeding in its orbit faster than any other planet in the solar system.
If you could stand on Mercury, you would see a bloated sun creep at a snail’s pace through a black sky. Mercury rotates extremely slowly on its axis once in about 59 Earth-days.
Because Mercury is so close to the Sun, temperatures on the planet’s surface can reach a searing 800 degrees. Mercury’s cratered surface looks much like the surface of Earth’s moon.
2. Venus
The second planet from the Sun, is only slightly smaller than Earth. The thick clouds of carbon dioxide and sulfuric acid that cover Venus reflect sunlight, making it bright but also trapping heat at the planet’s surface.
At 842 degrees, it’s hotter on Venus than on Mercury, even though Mercury is nearer the Sun. The thick, heavy atmosphere creates enormous pressure on Venus.
Space probes that have landed there have lasted only a few hours before the pressure crushed them. Venus spins in the opposite direction of its orbit around the Sun.
3. Earth
Life on Earth survives beneath a thin layer of atmosphere that shelters us from the dangers of space. “Ocean” might be a more appropriate name for this planet, because oceans cover nearly 70 percent of Earth’s surface.
4. Mars
The red planet, is the fourth terrestrial planet. A day on Mars lasts 24 hours, 37 minutes only slightly longer than an Earth-day. But Mars takes almost twice as long as Earth to orbit the Sun, going around once in 687 Earth-days.
Though Mars is a world with no rivers, it has winding valleys that look like dry riverbeds. Scientists believe that powerful floods once deluged Mars. Today the planet is too cold and its atmosphere too thin for liquid water to exist at the surface.
In 2002, the Mars Odyssey spacecraft detected large amounts of ice near the surface enough to fill Lake Michigan twice over. More water is frozen in the polar ice caps.
5. Jupiter
Jupiter, more than 300 million miles from Mars, is the largest planet in the solar system. If Jupiter were a hollow ball, more than a thousand Earths would fit inside. Despite its
size, Jupiter spins faster than any other planet, rotating every 10 hours.
However, it takes Jupiter nearly 12 Earth-years to orbit the Sun. Like the other gas giants, Jupiter is mostly hydrogen and helium. The temperature at the top of its colorful clouds is minus 220 degrees.
Down in the clouds, the temperature reaches 70 degrees at a depth where the atmospheric pressure is about 10 times as great as it is on Earth.
6. Saturn
The second largest planet, is the farthest from Earth of the five planets known to early stargazers. Galileo, in 1610, was the first astronomer to see Saturn and its rings through a telescope. Up to 1977, astronomers thought Saturn was the only planet with rings.
We now know the other gas giants Jupiter, Uranus, and Neptune also have ring systems, but Saturn’s is by far the largest, most visible, and most complex. Its rings are made mostly of ice. Saturn also has at least 30 moons.
The largest, Titan, is a little bigger than Mercury and is blanketed with a thick, nitrogen-rich atmosphere.
7. Uranus
Uranus (pronounced YOOR-un-nus), a large gas planet, blue-green in color, was discovered in 1781 by astronomer William Herschel; its rings were not discovered until 1977. Uranus is twice as far from the Sun as Saturn so far away that it takes sunlight about 2 hours, 40 minutes to reach it.
Uranus orbits the Sun tipped on its side, the result of what many astronomers think was a collision with a planet-sized body long ago. Saturn with its rings would just fit in the distance between Earth and the Moon.
Three Earths could fit across Jupiter’s Great Red Spot, a storm like a hurricane that has raged for centuries in Jupiter’s southern hemisphere.
8. Neptune
Neptune, the eighth planet from the Sun, is so far away that it takes 165 years to orbit the Sun. Like Earth, Neptune has seasons, but each season lasts for 41 Earth-years. Neptune is too distant to be seen with the unaided eye.
In 1989, the Voyager 2 spacecraft tracked a large dark storm like a hurricane in Neptune’s southern hemisphere and discovered great geysers of nitrogen on Triton, Neptune’s largest moon. Triton is the coldest body yet visited in our solar system, with surface temperatures reaching minus 390 degrees.
Tracking Visible Planets
All the planets travel within the narrow band of the zodiac, although they wander around a bit, so they can be easy to miss. Even if you have a pretty good idea about the location of the zodiac, you may still have trouble finding the planets.
For help, look at a sky map, which you can download from the Internet (with your parent’s permission) or find at the local library. Here are a few tips on recognizing the planets.
| Mercury. This small planet is hard to spot, but it is visible without a telescope, either just after sunset or just before dawn, always in the general direction of the Sun and never far from it. |
| Venus. After the Sun and Moon, Venus is the brightest object in the sky. It can sometimes be seen in daylight, but it is never more than three hours ahead of or behind the Sun. |
| Mars. Mars is called the Red Planet with good reason, but its brightness varies. Check its position in an astronomical almanac or guidebook. |
| Jupiter. Among the planets, Jupiter is second only to Venus for brightness. Its progress across the sky can seem so slow that you might mistake it for a star unless you track its movement for several nights. |
| Saturn. You will not see Saturn’s famous rings with the unaided eye, but the planet is bright enough to find. Like Jupiter, Saturn takes a long time to show movement, so consult an almanac or guidebook before scanning the heavens for it. |
| Uranus. This distant planet is barely visible to the naked eye under even good viewing conditions. It moves very slowly, so to the unaided eye it looks like an average star. Through a telescope it appears pale green. |
Asteroids, Comets, and Meteoroids
Other members of the Sun’s family include asteroids, comets, and meteoroids sometimes considered “cosmic debris.”
1. Asteroids
Asteroids are minor planets of the Sun. Estimates of their number range into the millions. Some are only a few feet in diameter. The largest, Ceres, is about 580 miles across.
Most asteroids orbit the sun in the huge expanse of space between Mars and Jupiter known as the asteroid belt or main belt. Sometimes asteroids get knocked out of the main belt into the inner solar system.
Asteroid fragments strike Earth every day, and scientists believe several large asteroids have slammed into Earth over the years.
2. Comets
Comets are often described as dirty snowballs because they are made of frozen gases embedded with rock and dust particles.
Most comets travel in long, oval orbits around the Sun. When a comet nears the Sun, the intense heat causes the gases and particles that were frozen together to “melt” and vaporize. The vapor forms a “tail” that may be millions of miles long.
3. Meteoroids
Meteoroids, meteors, and meteorites three are different aspects of the same members of the solar system. They start as meteoroids stony or metallic materials in space. Some are microscopic,others are huge.
Every day, Earth’s atmosphere collides with millions of meteoroids that burn in the tremendous heat created by the collision. If a meteoroid is large enough, the collision
is visible as a streak of light across the sky a meteor, or shooting star.
Some meteoroids survive the flaming fall to Earth without burning up completely. Those that make it to the ground are meteorites. Most meteorites are small, but the largest meteorite ever discovered weighs about 66 tons. It fell on a farm in South Africa.
Maybe enough here the discussion of the astronomy merit badge, for the rest I will discuss in the next session.
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