Northern Sky: June 19 – July 2
Summer is officially settling in. The summer solstice arrives at 10:52 p.m. on Sunday, June 20. At that moment the sun reaches a point over the Tropic of Cancer, and ends its annual journey north. Then it reverses and starts heading south again. Slowly. When the sun is near a solstice, it moves at glacial speed. It seems as though the sun is at its maximum height, and the days are about as long as they get, for two months centered on the summer solstice. In fact, the word “solstice” comes from the Latin for “sun standing still.” On that day the Earth will be lighted from the Antarctic Circle up to the North Pole and beyond to the Arctic Circle on the night side of Earth.
On June 24th, we get the last of this year’s three supermoons. This moon rises at 9:33 p.m., about eight hours after the moment of fullness. It may not look perfectly round, but it’ll be close to Earth and quite bright. It travels the night sky in Sagittarius, sitting right at the juncture of the lid and the handle of the Teapot of Sagittarius.
On July 2nd, Earth reaches aphelion, its farthest distance from the sun. Earth orbits more slowly when it’s farther from the sun, which means that as I speak, we’re slowing down.
This time of year, the stars and planets get barely six hours to strut their stuff. Venus gets much less; it shines through the sun’s afterglow, very low in the west-northwest, for barely an hour before setting. In the east, Saturn, and then Jupiter, rise around midnight. Saturn is in Capricornus, the sea goat, and Jupiter has moved into Aquarius, the water bearer.
At nightfall, you’ll see a brilliant star high in the south to southwest. This is Arcturus, the brightest star in the kite-shaped constellation Bootes, the herdsman. Below Arcturus we have Spica, the only reasonably bright star in Virgo, the maiden. Low in the south is the S-shaped body of Scorpius. Its most salient feature is Antares, a gigantic red star at the scorpion’s heart. Just east of Scorpius is the Teapot of Sagittarius.
Finally, a recent article in Astronomy magazine reminded me of a story I heard a long time ago. A reporter was covering a meeting of astronomers—where, I don’t recall—but there was, as usual, a room where lots of graduate students were standing by poster displays of their research. The reporter saw one who had a small table by him, and on it was a jar of dill pickles. So the reporter asked, what have dill pickles got to do with astronomy? And the grad student explained that the vinegar in the pickle brine was based on acetic acid, and his group had detected acetic acid in space. Well, now lots of organic molecules have been detected in space, including amino acids, the building blocks of protein, and precursors of DNA. And Astronomy magazine just reported that scientists have found another one.
Ethanolamine, an essential component of the membranes that enclose our cells, has been found in a cloud of gas and dust just 390 light-years from the center of the Milky Way.
This gets at the question of how life arose on Earth and perhaps elsewhere. Was life seeded from space? Seeded in the form of essential molecules that were synthesized in space, including ones like ethanolamine, which could have assembled themselves into membranes that encapsulated and protected the other essential molecules by forming little protocells? I’m going to stick my neck out and say this question won’t be resolved any time soon.
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The University of Minnesota’s public viewings of the night sky at its Duluth and Twin Cities campuses have been curtailed due to the COVID-19 pandemic. For more information, see:
Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet
Twin Cities, Minnesota Institute for Astrophysics: www.astro.umn.edu/outreach/pubnight
Check out astronomy programs, free telescope events, and planetarium shows at the
University of Minnesota’s Bell Museum: www.bellmuseum.umn.edu/astronomy
Find U of M astronomers and links to the world of astronomy at: http://www.astro.umn.edu
