Jupiter at Opposition

Jupiter will pass through opposition at 10:58HST today.

Jupiter and the moons Europa, Ganymede and Callisto (left-right)
Jupiter orbits the Sun once every 11.86 years. As the giant planet continues on its way the Earth swings around much faster on our inside track. As a result we lap Jupiter once every 399 days, passing between the planet and the Sun. During opposition Jupiter will rise at sunset, transit at midnight, and set at dawn. This makes the planet available for observation for the entire night.

Look for a bright object rising in the eastern sky after sunset. It is difficult to mistake for anything else, shining at it’s brightest during opposition, a brilliant -2.7 magnitude. For the remainder of the spring and much of the summer, the planet will be quite prominent in the evening sky.

Venus in the Daytime

With the Moon only a few degrees from Venus this afternoon, it should be relatively easy to spot the brilliant planet long before sunset.

Venus 28May2012
Venus photographed on 28May2012, about 13° from the Sun in the mid-afternoon sky
Spotting planets in the daytime is not that difficult, both Jupiter and Venus are bright enough to seen in full daylight. Venus is currently near maximum brilliance at about -4.6 magnitude, easily bright enough to see in a clear sky. There are a few helpful hints to make this easier.

Today the Moon will aid finding Venus in the sky as it is about 5° north of the Moon. Having the Moon nearby will not only aid in locating the Planet, it will also provide your eyes something to focus on.

Of course these bright objects will be even more dramatic after sunset when Mars will also be visible nearby.

Long-term, hi-res tracking of eruptions on Jupiter’s moon Io

UC Berkeley press release

NIRC2 image of Io
A NIRC2 image of Jupiter’s Moon Io
Jupiter’s moon Io continues to be the most volcanically active body in the solar system, as documented by the longest series of frequent, high-resolution observations of the moon’s thermal emission ever obtained.

Using near-infrared adaptive optics on two of the world’s largest telescopes — the 10-meter Keck II and the 8-meter Gemini North, both located near the summit of the dormant volcano Maunakea in Hawaii — UC Berkeley astronomers tracked 48 volcanic hot spots on the surface over a period of 29 months from August 2013 through the end of 2015.

“On a given night, we may see half a dozen or more different hot spots,” said Katherine de Kleer, a UC Berkeley graduate student who led the observations. “Of Io’s hundreds of active volcanoes, we have been able to track the 50 that were the most powerful over the past few years.”

Continue reading “Long-term, hi-res tracking of eruptions on Jupiter’s moon Io”


Only once before have I seen Jupiter and Venus this close, many years ago. Being close enough to fit in the same eyepiece field is quite interesting, particularly with enough magnification to see the moons and planet details well.

If you have not been paying attention the evening planet dance is in full swing, Mercury, Venus and Jupiter all in close attendance.

This evening was the close approach of Jupiter and Venus. I set up a telescope briefly to capture the conjunction. More than a little overexposed, but you can see the moons of Jupiter this way…

Venus and Jupiter
Venus and Jupiter in conjunction on Aug 27, 2016. The star at lower right is Beta Virginis

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.

Jove 26Mar2016
Jupiter under moderately good seeing from Waikoloa