Jon U. Bell

Sky Watch Host

Ways to Connect

On April 26, 1920, a debate took place concerning our Milky Way. Some astronomers thought we were at the center of our galaxy, for when you looked along the milky band of stars that defines the galactic disc, you saw roughly the same number of stars throughout. Other astronomers pointed to a concentration of star clusters in the direction of the constellation Sagittarius, and suggested that that was where the galaxy’s center lay.

Some parts of the sky have more bright stars than others. The stars are fairly randomly distributed, but it seems as though most of the really bright ones can be found in the winter evening sky. The evening skies of summer have some bright stars, too, but the fall sky and the spring sky are relatively empty of bright stars.

Samuel Clemens, better known as Mark Twain, died on April 21st, 1910. Twain was born in 1835, the same year that Halley’s Comet made an appearance in the heavens. In 1909 he wrote, “I came in with Halley's Comet in 1835. It is coming again next year, and I expect to go out with it.

There's a meteor shower going on. It’s coming out of the part of the sky where we find the constellation Lyra, the Harp, and for this reason is called the Lyrid meteor shower. This is not a very strong shower, but it does contain some bright fireballs, and the skies should be fairly dark this year, at least until the third quarter moon comes up after midnight. It should be possible to see as many as ten or more "shooting stars" each hour. Get away from bright streetlights. Face east, and then look upwards toward the zenith.

If you look off to the east tonight, or any night this month or next, you’ll find a star low in the sky after sunset. That eastern star is named Arcturus, which means, “bear chaser.” It’s called the bear chaser because Earth’s rotation causes this star to follow or “chase” the constellation of Ursa Major, the Great Bear in the Sky. The bear is to the north of Arcturus (you’ll recognize its back and tail as the Big Dipper, well up in the northeast.) Arcturus is in the constellation Boötes, the Herdsman.

Since the Hallstrom Planetarium began presenting shows at Indian River State College back in 1993, we have served three distinct groups: college students, who take classes and practical labs in astronomy, celestial navigation, and observations on the basic structure and contents of the Universe; school children, from Kindergarten through 12th grade, come on free field trips and discover the wonders of outer space, viewing exciting programs that are tied in with public, private and home-school curriculums.

It’s a busy week at Indian River State College’s Hallstrom Planetarium. I’m preparing a new program that opens Friday night. The new show is called, “Eclipse!” It will feature not only the stars and constellations that you can see in the evenings at this time of year, but also provide audiences with a guided tour of eclipses. We’ll discuss the myths and the folklore, the history and the science behind them. We’ll show you solar and lunar eclipses, partial eclipses, total eclipses, annular eclipses, transits and occultations too. What does all that mean?

The moon is full tonight. This is the first full moon since the beginning of Spring, so it’s called the Paschal moon, which determines when Passover and Easter occur each year. Easter always occurs on the Sunday following the first full moon of the spring season, it’s what folks used to call, a “moveable feast,” because the date of the observance changes from year to year. Since spring is underway, the Sioux Indians call April’s full moon, the Moon of Greening Grass; to the Winnebago, it is Planting Corn Moon.

Tonight the nearly full moon appears in the east at sunset. As darkness sets in, you’ll find that our nearest neighbor in space has some company – the planet Jupiter. There it is, a very bright star to the right of the moon. Along with Jupiter and the moon there is another star below them - it is Spica in the constellation Virgo the Maiden. One indicator of distance in space is brightness, although it isn’t entirely reliable. Some objects are just naturally brighter than others, but in the case of the moon, Jupiter and Spica, this method works.

Watch the sun and you’ll discover it gets around. But of course you can’t watch the sun, because it’s too bright to look at without hurting your eyes. If you could somehow dim down the sun enough, you could also see the stars in the sky at the same time. (Actually, there are times when this happens – during total solar eclipses.)Assuming you could see the sun and stars at the same time, you’d notice the sun drifts eastward like the moon, although not as fast as the moon. The moon moves 13 degrees a day; the sun only moves about 1 degree a day.

This is the Astronomers Alphabet. Today’s letter is “E.” “E” stands for “Earth” and “Ecliptic;” the ecliptic is the earth’s orbital path “E” means “Ellipse,” which is the shape of pretty much every orbit, including the Earth’s.

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