Venus and Jupiter meet and a full Moon swings low.
A long running planetary drama reaches its climax this week as brilliant Venus finally catches up and then passes Jupiter. All week long they will be a stunning sight in the evening sky and shift positions noticeably from night to night. By the end of the week they will lie more than two degrees apart. Meanwhile, Saturn is in its prime. The ringed planet transits the meridian a little before 10:30 p.m., local daylight time. That’s when it will look its best in telescopes. The morning sky belongs to Mercury. The fast-moving planet is easier to see this week as it brightens to magnitude 0.1 and now rises 1¼ hours before the Sun. Even still, binoculars will be a big help sighting Mercury in morning twilight.
This evening Jupiter and Venus are at their very closest. Only 1/3 degree separates the two bright planets, which means they both fit into the same field of view in binoculars or even a telescope used at low magnification. The two worlds appear the same size — both spanning roughly 32 arc seconds.
Full Moon occurs this evening at 10:20 p.m., EDT. This is the most southerly full Moon of the year. As a result, when it rises it will be roughly 25 degrees south of due east.
Earth is at aphelion today — the point in its orbit where it’s farthest from the Sun, which will puzzle anyone who believes that warm summer days happen because Earth is closest to the Sun. On this date we’re 152,093,481 kilometres from our home star.
Today distant and faint Pluto reaches opposition, which means it’s visible all night long. Finding it, however, is a considerable challenge. See page 24 of the current issue of SkyNews for information on tracking down Pluto.
With the Moon lighting up the sky over the July 3 – 5 weekend, searching out faint fuzzies isn’t really in the cards. But there are still deep-sky treasures aplenty. One of the season’s prettiest sights is the lovely double star Albireo. It has three things going for it. First, it’s easy to find. Situated in the constellation Cygnus, Albireo marks the foot of the Northern Cross. Second, its component stars are both reasonably bright at magnitudes 3.4 and 4.7. Third, and most important, it looks wonderful in just about any telescope. That’s largely thanks to the contrasting colours of its two suns. The brighter star is a lovely, golden yellow hue, while its companion is a pale, icy blue. Those colours tell us something about the stars themselves. Yellow-orange stars tend to be relatively cool compared with bluish white stars — 4,000 degrees Kelvin versus 12,000 degrees in this case. Albireo is a real celestial show piece, and for my money, looks best in small telescopes used at low magnification. About 25× is optimal — excess power puts too much space between the component stars and robs the double of its impact.
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