A trio of planets, plus one

Venus, Mars and Saturn all share a small patch of evening sky in early August – close enough to fit in the same binocular field.

There are several close passes between planets this month. Mars and Saturn start the month less than two degrees apart, with much brighter Venus off to the right. Then on the 10th, the three make a triangle with about three degrees between Mars and Venus and a similar amount between Venus and Saturn. Finally, on the 23rd, Mars and Venus are about two degrees apart and have moved off away from Saturn.

While this dance is going on, Mercury hovers below in the twilight glow, the “fourth musketeer”. Around the third week of August it starts waning visibly to a crescent, which happens fast – by the end of that week, the 21st, it’s a very slim crescent and might be getting difficult to see.

Jupiter rises after 9 and is at its best a few hours after midnight. It has a couple of double moon transits this month, but they’re all in the wee hours of the morning – like one on 3:30am on the morning of Friday the 13th. But of course, there’s lots of other detail to watch on Jupiter. Will the south equatorial band come back? What will it look like as it does? How well does the great red spot stand out in the absence of a band?

Neptune is at opposition on August 20, off the left point of Capricornus though technically it’s just over the border to Aquarius. It isn’t very high when it transits, only about 40 degrees, so it might be a bit more challenging than usual. Uranus rises about an hour and a half later and is best viewed in the morning.

The RASC Observer’s Handbook lists “Large tides” on Aug 11-13. I’ve been wanting an excuse to visit some of the tidepool areas on the coast, especially Fitzgerald Marine Reserve, and that’s especially pleasant on hot summer days when I’d like an excuse to head to the coast anyway. So I checked local tide information – and found, ironically, that the tides in that area are very mild on August 13. I’ve written before (SJAA Ephemeris, April, 2007) about the mismatch between the RASC tide predictions and what we actually see at the beaches here – predicting tides is much more complex than just knowing where the moon and sun are.

Amusingly, as I write this on July 10, it turns out there was an extremely low tide today ... but it was at 5am. Even though there’ll be another one tomorrow, I’m not sure I’m quite that dedicated to tidepooling!