By Scott Levine
If you need any more proof that summer is fleeting, as July becomes August we’re already in the last full month of summer.
Maybe you’ve noticed that we’ve been slowly and steadily losing daylight since June’s solstice. By the first weekend of the month, the sun sets before 8 p.m. for the first time since May.
This also brings us to what amounts to the start of meteor shower season. By late July, the Perseid shower has already started. This is the first of about 25 showers of at least moderate brightness that happen through the end of the year. The Perseids’ famous meteors tend to be frequent, bright and easy to spot. Plus, even though the dark night comes late, the weather is generally agreeable and many of us have some extra free time.
Meteor showers happen when Earth, as it travels in its orbit, catches up with and plows through clouds of pebbles left over by another object that passed through long ago. In the case of the Perseids, we’re looking at small fragments, most the size of grains of sand, of the comet Swift-Tuttle, crashing into our atmosphere and burning up about 100 miles above us.
This year, the shower is expected to peak on the night of Aug. 11-12, though you can look any night through the end of August. All you need to do is find a clear patch of sky and look up. Any part of the sky will do, but most meteors will appear to come from the direction of the constellation Perseus, in the north or northeast. Bring a lawn chair, someone you love and some bug spray and enjoy the night.
The night of the 11th will be particularly good for watching, though, because the moon will be a young crescent, which sets hours before we reach the deepest overnight darkness. If things go well, you could see as many as 60 meteors streak above you each hour!
That’s not all, though. On the night of Aug. 19, Jupiter reaches a point called opposition. In truth, it’s Earth that reaches opposition with Jupiter, as we race past it on the shorter, speedier inside track of our orbit. Jupiter’s about five times farther from the sun than we are and takes about 12 Earth years to orbit once.
Opposition is the spot where an object appears directly opposite another as seen by a viewer between. It’s the same arrangement when it’s a full moon. So, that night will have a bright “full Jupiter” but 500 million miles away.
If you point even a regular pair of binoculars at the giant planet – low in the south – you can see its four giant moons. As you look, try to imagine what it must have been like to be Galileo Galilee, when he first saw them through his small telescope in 1610. Could he have imagined that the biggest, Ganymede, is bigger than the planet Mercury and has an enormous ocean with more water than Earth does? Or that there were at least 75 other moons there that he couldn’t see?
These are great times to turn toward the skies. I hope you will this month!
Scott Levine (firstname.lastname@example.org) is an astronomy writer and speaker from Croton-on-Hudson. He is also a member of the Westchester Amateur Astronomers, who are dedicated to astronomy outreach in our area. For information about the club including membership, newsletters, upcoming meetings and lectures at Pace University and star parties at Ward Pound Ridge Reservation, visit westchesterastronomers.org. Star parties are free and open to the public.
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