Sun’s trajectory explains summer heat

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Hot, hotter, hottest, and it is not even mid-summer; that is South Texas for you. I hope that while you were out enjoying the 4th of July celebratory fireworks you were able to see Scorpius and Sagittarius striding across the southern sky behind the “rockets’ red glare.”

If the evenings are too hot to take a hike, the predawn sky will share the faint breezes along with Jupiter and Saturn in the east. These two gas planets will emerge above the horizon and join the hidden-by-daylight stars of the winter skies, which gave rise to the term the “dog days of summer.” The ancient Egyptians were highly-skilled astronomers and knew that the bright star Sirius, the heart of Canis Major, was in the sky throughout these several months and theorized that was what caused the great heat during this time of year.

Naturally, later scientists came along and had other hypotheses. Today, we explain the extraordinary heat of summer as being due to our planet’s 23.50 tilt and the location in its orbit around the sun. Plus, the countless square miles of paved over soil and plowed under trees which mean heat sinks into areas it would not ordinarily be able to sink.

Another factor you may ponder is how quickly the breezes develop as the sun rises higher into the sky and recall a science class long ago that mentioned to a sleepy class that warm air rises and cooler air sinks, which gives us a motion we call wind. Science is really a fascinating topic, and the more we learn the more interesting it becomes.

July means the sun is rising a bit later each day and setting a bit earlier – have you noticed that yet? We are moving continually, heading to the autumn equinox now. I have friends in Alaska who have been posting photos of the sun above the horizon at midnight where they live. It is totally amazing when we think about our home planet. Perhaps you would seek out a YouTube video to see this for yourself.

Constellations to enjoy during the summer include Cygnus the Swan, Aquila the Eagle, and Lyra, the Lyre. The brightest stars in these three constellations form the Summer Triangle mentioned last week. If you have a dark safe viewing site, you would be able to see the pattern clearly but most of us now have bright white lights along our streets which preclude seeing anything in the night sky except the Moon and Venus. The Evening Star is Venus, and I wonder now if the poem/song Twinkle, Twinkle Little Star is actually referring to Venus. The planet is so brilliant because it is reflecting sunlight from its poison-gas atmosphere

The atmosphere is filled with carbon dioxide and covered with clouds of sulfuric acid – not a place anyone would want to visit. This covering means that Venus is even hotter than Mercury. You think it is hot in Texas? It is hot enough on Venus (9000 F) to melt lead. Venus rotates on its axis opposite the direction Earth does. Planets do not generate their own light, merely reflect it, just as the Moon reflects sunlight. I don’t imagine anyone would prefer to live on Venus instead of Earth.

Until next week, take a bit of advice from the song in Westside Story that advises “keep cool” and I will see you next week. KLU.