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The month of July was named for Julius Caesar and was formerly the fifth month of the year.
July is the first full month of summer in the northern hemisphere and this year will bring us a major climax that will not be it happens again until September 2035.
This climax is a Perihelian opposition of Mars on July 27th. It is then that a planet is at its closest point to the sun at the same time as it is directly opposed to the earth by the sun. The last time this happened for March, it was August 27, 2003, when it was closest to the land for almost 60,000 years, about the time modern humans have started to migrate out of Africa. They were probably hunted during a sudden cooling period during the last ice age. It was a very dangerous time for humans because their numbers could have gone down to 10,000 worldwide.
We have returned to 7.5 billion, a little more than a billion people more than the last Perihelian opposition since. Mars was only a million miles closer to Earth 15 years ago at 34.7 million miles than it will be this time around. But this time it will be weaker on the Capricorn ecliptic than it was 15 years ago, so the views of many of its remarkable features across a telescope will not be as easy to see.
Take up the challenge of seeing as much detail as you can this summer while Mars is still big and brilliant because it will take 17 years until it gets closer again, allowing us to see it in some detail even without the use of a large professional telescope. Its two icecaps, several of its dark markings and part of its thin atmosphere should be pretty easy to see in a good amateur telescope, but more exciting features like Olympus Mons – the largest solar system volcano at three times the height from Mt. Everest with a base the size of Arizona and a caldera 50 miles wide at the summit will present more of a challenge. The volcanoes on Mars have been erupting for billions of years and have probably erupted 25 million years ago.
Another good challenge would be to find one or both of his moons, Phobos and Deimos, named for fear and terror. . Phobos, 14 miles in diameter, is the closest to Mars. Deimos is the furthest away, which makes it a little easier to find with a good telescope and a method to block most of the light of Mars
We only weigh a few ounces on Deimos and its speed of escape is 12 mph. so that you can orbit this little moon like Superman. On Phobos, you could throw a baseball in orbit, since you only have to throw it at about 24 miles at the time.
Being the inner moon, Phobos spirals towards the Martian surface at a rate of about 6 feet per century. which is about half the distance that our own moon moves away from us each century. At this rate, Phobos will crush on Mars in about 40 million years and our own moon will be too far away from Earth to create more total solar eclipses in about 100 million of us. years.
So enjoy this summer to explore the bright orange neighbor of ours, which still holds many mysteries even as many of its secrets are revealed. We already knew that there was water on Mars at one point, but we have just discovered concrete evidence for large organic molecules just below its surface and microbial activity further beneath it. surface, resulting in seasonal variations in methane release. Mars could still be an active planet below its surface, hovering over the cutting edge of habitability.
The stories of other planets will fade in comparison to the exciting possibilities of Mars this month, but they will provide a nice distribution of support. and are always interesting to watch with or without a telescope, and to continue to learn more about them, since we really know very little about our seven other planets.
Venus sets a little earlier in our western sky evening, about an hour after sunset. But it gets bigger and brighter when it catches up with us in our orbits. It will be two sizes, or more than six times brighter than Mars. Venus will appear as a gibbous moon descending through a telescope, shrinking 70 percent to only 57 percent lit by the sun.
Venus will participate in two excellent close conjunctions this month, one with one planet and the other with a star. Venus will be just one degree above and to the right of Regulus in Leo on the 9th, very close to where the sun was back on August 21st of last summer when it was eclipsed by the Moon. Then Venus will be less than a degree to the left of a thin lunar crescent on July 15 with Mercury below and to the right of the pair about 45 minutes after sunset.
Jupiter continues to fade a bit this month it is farther into space in our respective orbits. The king of the planets will finish his retrograde or western movement in Libra on July 11th. Jupiter will not even be as bright as Mars this month, which is very unusual.
Saturn was in opposition last month, so it is now getting up just before sunset and still visible all night long. Its golden glow fades slowly, but it is even brighter than usual and its rings are open at 26 degrees, which is close to its maximum. The ringed planet is still retrograde in Sagittarius near the Lagoon and Trifid nebulae along an arm of our Milky Way.
Pluto is even in opposition this month, in the teaspoon of Sagittarius. Orbiting the sun once every 248 years, Pluto spends nearly 21 years in each constellation of the zodiac. It will only reach 14.8 magnitude this time, which is 2.5 million times weaker than Mars.
JULY HIGHLIGHTS
July 4: Henrietta Swan Leavitt was born that day in 1868. She was an American astronomer at Harvard who discovered the period-brightness relationship of the Cepheid variable stars that we allowed to measure the universe and to establish a scale of distance [5]
July 5: Isaac Newton publishes his Principia Mathematica in this day of 1687
6: The Earth is at l & # Aphelion, or farthest from the sun today at 94.2 million miles. The last quarter moon is at 3:52
July 9: Venus will be one degree above Regulus, and 15 degrees above and to the left of Mercury half an hour after sunset.
July 10: The thin lunar crescent will be very close to Aldebaran at the Taurus just before sunrise this morning. It will obscure this giant red star in parts of Canada
July 11: Mercury will be at a low in the western evening sky after sunset tonight.
July 12: The new moon is at 22:49 [19659002] July 14: The moon is just above Mercury tonight
July 15: The moon will be very close to Venus tonight 45 minutes after sunset Sun.
July 16: On this day in 1994, the 21st Comet Shoemaker-Levy 9 pieces slammed into Jupiter, leaving a big black mark that lasted a few weeks. I saw up to five of these marks at a time during six days while another piece descended into the Jupiter atmosphere about every six hours.
July 19: The first quarter moon is at 15:53
July 20: The moon is just above Jupiter tonight. On this day of 1969, the first humans, Neil Armstrong and Buzz Aldrin, set foot on the moon, just 66 years after the first primitive plane was flown by the Wright brothers.
July 24: The moon is just above Saturn tonight
July 27: The full moon is at 4:22 pm This is also called the Hay or Thunder Moon.
July 30: Mars will be at its closest to Earth in 15 years tonight.
Bernie Reim of Wells is co-director of the Northern New England Astronomical Society
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