What are those things in the sky

Vernon Whetstone
Tuesday, September 25, 2007

 

One nice thing about writing an astronomy column is the questions I receive, which I am happy to answer. These come mostly from being stopped on the street or phone calls and even one internet e-mail question.

Almost all start with the phrase, "What is that bright thing," or "I saw something last night," or a variation thereof.

I am happy to answer these questions because they almost always lead to a discussion of astronomy in general and how to get involved in the pursuit of "things out there."

So, with thoughts of "killing two birds with one stone" in mind, I am going to address the most often asked questions here.

Question one: "What is that bright thing in the southwest in the evening just after sunset?" That one is easy: it's the planet Jupiter, currently in the constellation Ophiuchus (pronounced o-FEE-ooo-cus). It will be there until December when it will cross into Sagittarius where it will spend the next year.

Jupiter takes 12 years to orbit the Sun and spends, on average, one year in each of the 12 zodiacal constellations along the ecliptic. While Ophiuchus isn't one of the zodiacal constellations, in astronomical circles it is sometimes called the 13th sigh of the zodiac.

Even though Jupiter is in Ophiucus, it is five degrees to the right of Antares, the brightest star in Scorpius, which is a zodiacal constellation. Five degrees is about the same as the width of your clenched fist held at arms length.

Question two: "What is that bright thing in the east just before sunrise." Again, that is easy. It is the planet Venus. Although Venus is only partially lit by the Sun (through a telescope now it will look like a very slender crescent Moon), it presents a dazzling spectacle in the morning sky.

Jupiter and venus are not the only planets visible right now. Mars, rises just after midnight. Saturn, emerging from behind the sun, rises just after 5 a.m. and is in conjunction with Regulus, the brightest star in Leo, the Lion. The pair are, however, dim and low on the eastern horizon.

Question three: "I saw something last night, it was like a bright flash high in the sky, it didn't last long, but it was sure bright."

Assuming the viewer didn't see an exceptionally bright meteor, it may have been an Iridium Flare, the reflection of the Sun off of a facet of an orbiting communication satellite. They are beautiful to see, and appear almost like an exploding star

The Iridium fleet was originally intended to enable satellite telephone communication. It was a novel idea, but a few years ahead of its time. The original company went bankrupt. The assets, including the satellites already in orbit, were purchased by another company which is attempting to make a go of it.

If you want to see an Iridium Flare, go to www.heavens-above.com. Provide your latitude and longitude (available from a provided database) and it will give you the time, location, and direction of the next flare visible from your area. They are fun to look for and to watch.

So, "keep those cards and letters coming in folks" and perhaps your question will make a future column.

SKY WATCH: Full Harvest Moon tonight, Sept. 26, which will wash out any planned viewing except for the brightest stars and planets. Mercury and Spica are visible in the west but look quick, they will set soon after the sun. Binoculars will be essential since they are in the glowing haze of sunset. The moon will be near the Pleiades star cluster on Sept. 29 and 30. On Oct. 2 and 3, look in the east for a conjunction of the Moon and Mars at about 1 a.m.