The Moon and Jupiter

This evening at sunset a nice crescent Moon and the bright planet Jupiter will be quite close. As sunset around 19:00 the two will be separated by a mere 46′, just a little over the width of the full Moon. The two should make a very attractive pair as they sit above the glow of sunset.

Keep an eye out for Mercury and Venus closer to the horizon. At 19:00 Venus will be 9° above the horizon with Mercury a bit higher at 14°. The Moon and Jupiter will be higher yet around 25°. Since Mars and Saturn are also visible in the southern sky all five naked eye planets will be visible.

All Five Planets Visible

For much of the month all five naked eye planets will be visible at sunset. Mercury, Venus, Mars, Saturn, and Jupiter can all be seen easily if one knows where to look. Indeed, four of the five are quite bright and quite hard to miss. Neptune and Uranus are generally too faint to be seen without optical aid.

Venus and Jupiter over the Keck 1 dome
Tonight, August 1st, Venus is just rising high enough to be easily seen. It will be a mere 5° above the horizon at 19:30, probably bright enough to be seen against the glow. You can find Mercury a little higher, about 10° above the horizon. Jupiter is obvious well above the sunset as a bright object shining at -1.7 magnitude. Mars and Saturn are visible to the south on the top of Scorpio.

There will be a nice conjunction of the Moon and Jupiter, only 46′ apart, on the 5th of August. Mercury reaches eastern elongation on the 16th of the month. A beautiful triplet of Mercury, Venus, and Jupiter will gather in the days around the 22nd. Keep an eye to the sky for the month to be treated to some nice planetary views.

Jupiter Again

After a stormy Friday night we had clear skies and decent seeing over Waikoloa again last night. Again I set up the telescope for a little planetary photography. The seeing was marginally better, and so is the resulting image.

The night also featured three moons in close to the planet. Io can be seen alone to one side of the Planet while Europa and Ganymede form a close pair. Ganymede is the larger moon and slightly closer to the planet

I really need to do this from the summit under good seeing some time.

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Jupiter under moderately good seeing from Waikoloa

Jupiter High

Jupiter passed through opposition back on March 7th. Thus the giant planet is high in the sky through much of the night, well placed for observations.

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Jupiter on March 24th from Waikoloa
I was thinking of going to bed, but it was a hot windless evening in Waikoloa, not much point in trying to sleep before it cooled off a bit. The dead calm conditions made me think… What is the seeing like? A question only an amateur astronomer would ask.

Turns out the seeing was pretty good. The typical horrible seeing in Waikoloa is 2 to 3 arcseconds or worse, when the trades are blowing it can be quite bad. I suspect the seeing was 1 arcsecond or better last night, the view of Jupiter in the eyepiece was quite pleasing. Putting a camera in place of the eyepiece yielded video worth the effort in processing.

The Moon and Jupiter

The Moon and Jupiter will rise together this evening of January 26th. The Moon will rise first, around 20:40HST, followed by Jupiter half an hour later at 21:25HST. Over the course of the night the Moon will slowly approach Jupiter, closing to about 4° by dawn.

The following evening, January 27th, the order will be reversed, with Jupiter rising first at 21:21HST and the Moon rising twenty minutes later at 21:40HST, with about the same separation of 4°.

Five Bright Planets in the Dawn

All five planets that are visible to the unaided eye can be found in the dawn for the next few weeks. Jupiter, Saturn, Venus and Mars have been visible in the dawn for some time now. Arriving late to the party is Mercury, just rising out of the glow of dawn. Mercury is headed for maximum elongation on February 7th, rising to 24° ahead of the rising Sun. The line of planets will persist for a week or two after that as Mercury drops back into the glow of dawn after elongation.

Zodiacal Light
False dawn, actually zodiacal light, rising over Mauna Kea
Highest in the sky is Jupiter, shining at -2.3 magnitude and rising before 10pm. Mars rises next, around 1am, seen as a ruddy red object, much dimmer at +1 magnitude. Saturn will rise around 3:30am in Scorpio near Antares, shining at +0.5 magnitude. Venus rises around 4:45am and will be quite obvious, the brightest of the five at -4 magnitude. Last will be Mercury, currently rising just before 6am and shining at +1.2 magnitude. It will rise earlier and earlier as it approaches maximum elongation, rising at 5:20am on February 7th. As Mercury reaches it highest it will be only 4° from Venus.

Together the five planets neatly outline the ecliptic, the plane of our solar system revealed by simply connecting the dots across the sky. As dawn approaches, but before the start of twilight around 6am, look for the zodiacal light, the bright glow of interplanetary dust also seen along the ecliptic.


I missed the closest approach of Venus and Jupiter. Not for lack of trying. I had set up the telescope and camera in the driveway. A clear afternoon clouded over at sunset, leaving me only glimpses of the planets through a fleeting gap in the clouds. I had time to focus enough to see the crescent of Venus, which promptly faded from sight.

The next evening I am on the summit. No small telescope available, but I did have the camera to record a stunningly beautiful evening atop the mountain.

Venus and Jupiter over the Keck 1 dome