OBJECT IN THE SKY
“The International Space Station (ISS) made at least two visible passes over Wisconsin (taking sky cover into consideration) at around 9:00 PM (0200 GMT or Zulu) during the latter part of March and early April. It is difficult to mistake the ISS for any other object in the sky. Often passing high in the sky, it appears brighter (magnitude between –2.0 and –3.6 during these passes) and faster than an aircraft but much steadier and slower than a meteor. Depending on the time and the season, it fades as it enters Earth’s shadow and disappears from sight.
As the ISS ascends this month, it passes Venus, which is currently almost due west glowing at a magnitude of about –4.2 at an elevation of a bit over 35° above the horizon at around 9:00 PM. The word magnitude is often used to describe the brightness of an object. A better description might be that of the “dimness” of an object, because the larger the number, the dimmer the object. Objects with negative magnitudes (numbers smaller than zero) appear quite bright in the sky.
Venus is the brightest object in the night sky. The ancient Greeks thought it was a beautiful planet and named it Aphrodite (Αφροδίτη) after their goddess of love, beauty and procreation. Her name is the source of our word “aphrodisiac”. The Greeks had at least four different words for love, including storge, philia, agape, and eros. The type of love associated with Aphrodite was eros; more about this word later. There are different versions of Aphrodite’s birth. One version states that she was the daughter of Zeus and Hera. According to this version, Hera arranged for Aphrodite to marry Hephaestus (Vulcan, to the Romans), who by most accounts was powerful, ugly, gruff, lame, and according to one writer, “not the greatest catch”.
The planet Aphrodite, or Venus, makes an approximate right triangle with Earth and the Sun this month. This accounts for Venus being so high in the sky after sunset. The temperature on the surface of Venus is about 864 °F (462 °C) and is hot enough to melt the metals lead or tin. It is also hot enough to evaporate sulfuric acid, which condenses higher in the atmosphere to form dense white clouds. These clouds reflect about 75% of the sunlight falling on them, more than any other planet. This is the main reason for Venus being so bright. Carbon dioxide is the primary component of the atmosphere of Venus. This gas has caused a runaway “greenhouse” effect on Venus and has contributed greatly to the high temperature at its surface. We Earth-dwellers might take a lesson.
Aphrodite has been styled by a latter-day writer as the “first of the red-hot lovers” and was not particularly faithful to Hephaestus. Her most famous affair was with the god Eros (Έρως), whose name has been used to represent sexual love from the classical period of Greece (ca. 500 B.C.) onward. We derive the adjective “venereal” from Venus, the Roman, or Latin, name for Aphrodite. This goddess, by whatever name, was immensely popular among the ancients. She was known to punish those who did not take sufficient notice of her. The worship of Aphrodite in the Mediterranean region derived from the earlier cults of Astarte among the Phoenicians and her cognate Ishtar among the Sumerians to the east.
Venus is often known as the “morning star” or the “evening star”, depending on when it is observed (even though it is a planet and not a star at all). During this month and into the summer, it will continue to be the “evening star”. It revolves around the sun once every 224.65 Earth days. Mercury, known as Hermes (Ερμής) in Greece, is the swiftest of our planets. It has an orbital period around the Sun of only 88 days and appears to ascend and descend in the twilight on Earth over a small number of days.
Although not exactly the same type of motion, the ISS makes a complete circuit around the Earth roughly every 90 minutes. We wonder what the ancient Greeks would have made of that.