Healer in the sky
Prominent in this month’s sky is the constellation Ophiuchus. To locate Ophiuchus, look in the southern sky about 10:00 p.m.; it is located just above Scorpius.
There is some disagreement over the origin of this constellation. Apparently it was once known as Asclepius, who was the Greek god of medicine. Asclepius was the son of Apollo and a nymph called Coronis. He was taught the art of healing by the centaur Chiron. After his training, Asclepius became the surgeon to the Argonauts and sailed with them on the ship Argo. Onboard, he managed to bring life back to a number of people, including the son of King Minos of Crete.
It was after Asclepius tried to revive Orion, who had been bitten by the scorpion, that Pluto began to complain to Zeus. Pluto was afraid that if Asclepius had his way he would rob the entire population of Hades. Zeus agreed that they could not allow men to be immortal, so he ended Asclepius's life with a thunderbolt. Zeus placed Asclepius in the heavens along with a serpent as symbol for renewed life.
Ophiuchus is possibly the only constellation in the sky that is patterned after a real person in human history. Some believe the origin of this constellation was a famous Egyptian mortal named Imhotep, who lived in the twenty-seventh century B.C. He was honored by both the Egyptians and Greeks some twenty-five hundred years after his death as not only a great man but as a god who owed his great powers to the knowledge of medicine.
This month, the planet Pluto resides in the constellation Ophiuchus. Because of its distance from the Sun and its small size (1,413 miles in diameter), Pluto is not visible without a good telescope. Though Pluto is considered the farthest planet from the sun, its orbit is not circular. Due to the eccentricity of its orbit, it is closer than Neptune for twenty years of its 249-year orbit. Pluto crossed Neptune's orbit on January 21, 1979, and made its closest approach to the sun on September 5, 1989. Pluto again crossed the orbit of Neptune on February 11, 1999, again making it the farthest planet. It will not be until September 2226 that Pluto will be closer to the Sun than Neptune.
Pluto has one known moon, Charon. What is unique about this moon is that it is about half the size of its parent planet. Pluto's rotation period is 6.387 days, the same as its satellite, Charon. Although it is common for a satellite to travel in a synchronous orbit with its planet, Pluto is the only planet to rotate synchronously with the orbit of its satellite. Thus, Pluto and Charon continuously face each other as they travel through space.
On July 5, the Earth will be at its farthest distance from the Sun, 310,000 miles farther away than on January 4. This is also the point of our slowest orbital speed around the sun. That is why summer in the northern hemisphere is the longest season, five days longer than winter.
This is a dull month for planet viewing, as most of the planets start the month in the glare of the Sun.
- Venus, just having crossed the Sun, will become a morning star and should be visible low in the twilight in the middle of July.
- Mars is getting very close to the Sun in the evening sky this month. It will be difficult to spot.
- Jupiter is still an evening star, but will be very low in the west near the end of the month. Look for a crescent Moon and Jupiter low in the sky one hour after sunset on July 21. The star Regulus will be on the horizon to the lower right of Jupiter.
- Saturn, too, is in the glare of the sun, but should become visible as a morning star near the end of the month.
- Get ready for a Blue Moon. There are two full moons this month, on July 2 and July 31. The New Moon is on July 17.
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