The Solar System is a true system, defined as a group of structures or elements which together form a functional unit. Science teachers incorporate the physics of energy and motion to explain how Solar System bodies move and remain in orbit. Visual (non-telescopic) astronomy affords impressive views of many objects in the Solar System. This includes six of the major planets—four terrestrial rocky planets, Mercury, Venus, Earth, and Mars, and two gas giant planets, Jupiter and Saturn. Two ice giant planets, Uranus and Neptune, are much larger than the four terrestrial planets, but smaller than the gas giants Jupiter and Saturn. Therefore, they are not generally visible without a telescope. Earth’s satellite, the Moon, constantly assumes different appearances as it revolves, waxing and waning throughout the lunar month. The Sun, the Solar System’s central star, also varies in elevation, intensity, and times of rising and setting due to Earth’s rotation and revolution.
Stars are not part of our Solar System, but the unaided eye may perceive over 2000 nearby stellar bodies presiding magnificently over Earth residents on a clear night, not to mention one or more Solar System planets visible on virtually any given night. They appear to be placed on the imaginary, infinitely distanced celestial sphere which surrounds Earth, a terrestrial planet also known as the terrestrial sphere.
Many Solar System wonders are readily visible, but modern “light pollution” is an increasing handicap for envisioning objects on the celestial sky dome. We will recount several memories of Solar system wonders we offered to public school students during the last three decades of the 20th century. Prior to October each year we researched calendar dates of the dark phases of the Moon. We needed to know when the moon was not visible in our night sky. Those dates allowed for planning a dark sky “Star Watch” event for our astronomy students.
Dark skies facilitated observation of stars and planets. After a short talk in the gym by “Pastor Pete,” my own pastor, we proceeded outdoors for a group session to highlight visual identification of well known objects or star groups. I discovered that a flashlight with a narrow beam held as high as possible could direct student attention to individual stars, planets, constellations, and asterisms. We could instruct students concerning distances to selected stars. For example, in the asterism Summer Triangle which was dipping toward the west in October evening skies, we pointed out bright Vega, to our eyes’ fifth brightest star in the sky. It is a relatively close star at 25 light years. Also in the Summer Triangle is Deneb, about 1500 light years distant. It is a supergiant star, enormously larger and intrinsically much brighter than Vega, but appearing dimmer—only 19th brightest—because of its great distance.
Students were invited to view the skies through the pastor’s fine tracking telescope and several Astroscan telescopes owned by the school district. Several highlights were Jupiter with its four brightest moons, Saturn with its beautiful ring system, and Albireo, appearing as a single star to the naked eye, but resolvable even in a low power telescope to an impressive double star—one bright yellow, accompanied closely by a dimmer but incredibly blue-hued companion. Color indicated differences in stellar temperature.
The visible objects on those ‘watch’ evenings were all stars or planets within our home galaxy, the Milky Way. There was one exception. Some telescopes occasionally focused on Andromeda, a nearby neighbor galaxy. That “object” is really an entire galaxy of billions of stars in an apparently tightly bound group. It is visible as a tiny “fuzzy patch” through binoculars if one knows precisely where to look. It is sometimes called a twin of our Milky Way Galaxy. At two million light years distant, it is really 220,000 light years wide and contains as many as one trillion stars.
We pointed out circumpolar constellations and asterisms such as the Big Dipper, the Little Dipper, and Cassiopeia. These are star groups which never dip below the horizon at the latitude of New Jersey. They apparently revolve around the North Star, also known as Polaris. This famous star, sometimes called the Pole Star, is located directly above the geographic north pole of Planet Earth. The Earth’s extended axis never deviates from Polaris, day or night, summer or winter. Consequently, certain constellations such as the Big Dipper spend 24 hours apparently revolving around Polaris. This is caused by the real motion of Earth’s constant 24 hour rotation.
Following up on the above facts, our readers will understand our final instructions to students before they traveled home for a short night of sleep. Students were instructed to take note of the location of the Big Dipper. It was very low in the northern sky. Leading up to the star watch, students had been instructed to return to school in pitch darkness the next morning. In Northern New Jersey, that means 5:43 AM on Oct. 21, for example. That hour corresponds with ‘astronomical twilight’ during which the sun is between 18º and 12º below the horizon. We enjoyed about one-half hour of darkness before the onset of dawn’s early light.
Students who arrived at 5:43 AM were able to view the Big Dipper, now high in the heavens. Earth had rotated substantially while they slept. The Big Dipper had apparently revolved to a position over their head, its handle now pointing toward the horizon! In addition a brilliant star field had become visible in southern skies, enclosed by an asterism of six bright stars named the Winter Hexagon. This phenomenon provided a convincing demonstration of Earth’s rotation. Our planet had rotated approximately 8000 miles eastward while students slept!
Most male students took advantage of the opportunity to play touch football when they returned from the soccer field after observing the position of the Big Dipper and the new glory of stars enclosed by the Winter Hexagon. Most female students chatted in the cafeteria, waiting for the bagels prepared by their mothers. One year every student in our Earth Science classes attended both the evening and morning sessions even though their attendance was optional. Students were permitted to sleep in class that day, a privilege understandably forbidden on all other days.
The grandeur of the dark heavens was not lost on the students. In the initial group session “Pastor Pete” made reference to God’s vacuum cleaner, Planet Jupiter, whose strong gravity deflects harmful comets away from Planet Earth. The glory of God’s creation was apparent to all students and staff in attendance. Our star watches remain as cherished memories.