Celestial Lights
By Phyllis Burton Pitluga (June 2, 2006)
June's Celestial Lights
Jupiter is the celestial gem of our June nights this year. It is already up in the southeastern sky after sunset, and it crosses the sky all night long as our planet Earth spins. Jupiter sets before sunrise. In the Roman pantheon of gods, Jupiter reigned supreme as God of the Skies and was the equivalent of the Greek god Zeus. Here in Mexico, the sky god called Bolon Dzacab was described as a god worshipped at New Year ceremonies. Bolon Dzacab has been associated with God K, who is linked with the year and may be personified by the planet Jupiter, whose cycle in our sky is 399 days (some 30 of those days it is hidden behind the Sun). For example, Jupiter was in "opposition" on May 4 of this year (when Jupiter, the Earth and Sun are in line, causing Jupiter to rise at sunset). In another 399 days Jupiter will be in opposition again.
The amazing thing about the planet Jupiter is that, if you have good distance vision, you can even see four bright moons orbiting Jupiter. (One night, I was operating a telescope for the public and explaining the arrangement of the moons; one person in line said "I can see them now, only the arrangement is reversed"-as it should be without the optics of the telescope!) This means that with a pair of binoculars you can see that the moons change position from night to night. It was just this observation in 1610 of moons orbiting Jupiter that caused Galileo to embrace the Copernican system of our planets orbiting the Sun instead of the then-taught system of everything whizzing around the Earth. As of the latest count, Jupiter has 62 moons, most of them discovered in images taken from spacecraft visiting the Jupiter system. Some of these moons may be sites for future exploration to detect life elsewhere in our Solar System. Jupiter is also embraced by a faint ring system.
Jupiter is the largest of all the planets in our Solar System. Its diameter is more than 10 times that of Earth (88,000 miles, compared to 8,000 miles). In a telescope of moderate size, you can see belts of dark clear atmosphere separating brilliant white clouds into about a dozen zones. One feature in these clouds is a huge storm called "the Red Spot" that swirls like a hurricane in this world with a very deep atmosphere. The Red Spot is so big it could swallow two Earths.
Jupiter is five times farther from the Sun than Earth, so that the light falling upon the cloud tops is only 1/25 of the light here at Earth. Yet, Jupiter radiates away more energy, so we know that heat is being produced in its interior from gravitational squeezing as it slowly shrinks. Another amazing fact about this giant planet is that it spins unbelievably fast: at the equatorial cloud tops, Jupiter is spinning at 28,000 miles per hour (versus the equatorial surface of the Earth, spinning at 1,000 miles per hour). This rapid spin causes the planet to bulge at the equator and to be flatted at the poles; you can see this in a telescope view.
So, identify Jupiter with certainty on June 8 when the Moon passes underneath Jupiter. Test your eyesight to see if you can see Jupiter's four big moons without using any optical aid. Then, enjoy becoming acquainted with the God of the Skies through binoculars and telescopes.
Sky Calendar, June 2006
By following the Moon as the biggest and brightest "pointer" in the sky, during the month you can identify different planets and bright stars.
Saturday, June 3: First Quarter Moon
Wednesday, June 7: Moon passes just above the bright star Spica, a hot star that is 262 light years away and is a multiple-star system
Thursday, June 8: Moon passes below the planet Jupiter
Saturday, June 10: Moon passes just below Antares, a Red Giant star that is 604 light years away; Antares has a companion star and is a star that irregularly varies in brightness
Sunday, June 11: Full Moon-for the next two weeks the Moon rises about 50 minutes later each night
Saturday, June 17: Mars just above Saturn low in the northwest during evening twilight
Sunday, June 18: Last Quarter Moon-the Moon rises at midnight
Tuesday, June 20: Mercury visible low in the west-northwest during evening twilight below Mars and Saturn
Wednesday, June 21: Summer Solstice, when the Sun rises furthest to the northeast, passes northernmost at Local Noon, and sets furthest to the northwest
Friday, June 23: Crescent Moon passes just above the Pleiades Star Cluster and above Venus in the pre-dawn sky
Sunday, June 25: New Moon
Wednesday, June 28: Moon passes above Mars and Saturn
Phyllis Burton Pitluga is Astronomer Emerita of the Adler Planetarium and Astronomy Museum, Chicago, and is now a San Miguel resident.