Jon U. Bell

Sky Watch Host

Ways to Connect

We’ve got pretty much an all-day event going on here at the Hallstrom Planetarium on the main Fort Pierce campus of Indian River State College. Starting at 7 o’clock this morning, we’ll have telescopes and solar filters set out for viewing the transit of Mercury. For about seven hours, the planet Mercury will be directly between us and the sun, and with a properly filtered telescope, you can see it as a small, black round dot against it. The transit will end a little before 3 o’clock in the afternoon.

The moon is new today, between us and the sun, and therefore it can’t be seen. The moon is also at its closest distance to us this month - what’s called perigee - a mere 222,000, miles, approximately. That’s less than the average distance of roughly 238,000 miles, and way less than the far-out apogee distance of about 252,000 miles. When the moon is full or new as it is now, we have very high high tides and very low low tides. That’s because when the moon, the Earth and the sun line up, the tidal pull on the Earth and its oceans is intensified.

Thu May 5, 2016 HYDRA

May 5, 2016

Not quite a hundred years ago, professional astronomers established eighty-eight official constellations in the sky. 48 of these star patterns had been recognized since antiquity; the rest were invented by navigators and star chart makers, beginning in the 16th century. One of the ancient constellations, recognized by the ancient Greeks is Hydra, and it is the longest and largest of all the star-figures in the heavens.

After sunset this evening you’ll find two bright stars in the east. In the southeast is Spica, the brightest star in the constellation Virgo the maiden. The very bright star far off to the left of Spica, in the northeast sky, is called Arcturus. To the Shawnee Indians, Arcturus was known as Waupee, or the White Hawk. One day Waupee saw a magical basket descend from the sky. In the basket were twelve sisters. When the basket reached earth the heavenly sisters leaped out, and linking hands, began to dance in a circle.

The Eta Aquarid meteor shower is at peak activity the next two nights. These particular meteors are bits of dust from Halley’s Comet, plunging into our atmosphere at roughly 150,000 miles an hour, where they are vaporized, heating up the air around them and causing that momentary streak of light you see in the night sky. The best time to see this shower is from late evening until sunrise. If skies are free of interfering clouds or streetlights, go out starting about 10 PM. Face east and look up toward the top of the sky.

Divide the year up into four parts or quarters. Each quarter is marked by the beginning of a new season. The quarter days of Summer and Winter are known as solstices, when the noontime sun reaches its highest or lowest altitude in the sky; while during the equinoxes of Spring and Autumn, nights and days are of fairly equal length. Now divide those seasons in half and you get cross-quarter days, the midpoints of each season. May 1st marks the cross-quarter day for Spring, called Beltane in the old Celtic calendar.

The earth’s seasons are caused by the motions of our planet as it rotates and revolves, and by its inclination or tilt from the straight up and down as it orbits, causing the sun’s path to change through the year. In an ancient Greek myth, Persephone, the daughter of the earth goddess Demeter, was kidnapped by Hades, god of the underworld. Mourning her loss, Demeter neglected the earth and the crops died, the air grew cold, and winter came to the land. When Persephone was rescued, Demeter caused the earth to bloom, and spring returned.

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.

The earth revolves about the sun, which causes the sun to slowly drift through our sky from west to east. The sun has now entered the constellation Aries, the Ram. This means that because of the earth’s revolutionary motion, the sun is now directly between us and the stars which make up Aries. This obviously is a bad time to be looking for the constellation of the Ram, because the bright sun blocks our view of this part of space. If today’s your birthday, you may have been told that you’re a Taurus, meaning the sun was in Taurus when you were born.

On April 26th in the year 1920, a great debate took place concerning the earth's place in our Milky Way Galaxy. Some astronomers such as Heber Curtis 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. Curtis also thought that spiral nebulae were distant galaxies, like our Milky Way, but very far away.

If you were outside this morning before sunrise, and happened to have a clear sky, you may have seen the old gibbous moon, well up in the south. You may have also seen three stars nearby the moon; but only the bottom-most star is actually a star: it’s the red giant Antares, which marks the heart of Scorpius. Just above Antares is another red-tinged star, but that’s not a star at all – it’s Mars. You can see how Antares got its name when you compare it to Mars – they look a lot alike, especially in color. Antares means, “rival of Ares,” the Greek name for Mars.

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.

Bright moonlight will interfere with our viewing of this year’s Lyrid meteor shower, which is at peak activity tonight. Every year at this time, the earth travels through a portion of its orbit that is littered with bits of ice and dust left in the wake of a passing comet - the Lyrid meteors, so named because they seem to come out of the part of the sky near the constellation Lyra the Harp. It’s been a reliable shower, viewed by millions of people for many years.

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.

In our Milky Way galaxy alone there are an estimated 200 billion stars. They vary in mass and size. Some, like the red supergiant star Betelgeuse, which can be found in the constellation Orion over in the western sky this evening, are as large as the span of the inner solar system. Others, like the blue giant Rigel, also in Orion, are many times hotter and more massive than the sun. Then there are white dwarf stars like the companion star to Sirius in the southwest - only the size of the earth. Smaller still are neutron stars, just a few miles in diameter.

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