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.

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.

​Mars Lost an Ocean’s Worth of Water

W. M. Keck Observatory press release

A primitive ocean on Mars once held more water than Earth’s Arctic Ocean, according to NASA scientists who measured signatures of water in the planet’s atmosphere using the most powerful telescopes on Earth including the W. M. Keck Observatory in Hawaii. The results are being published in the journal Science on March 6, 2015.

Mars with Oceans
NASA scientists have determined that a primitive ocean on Mars held more water than Earth’s Arctic Ocean and that the Red Planet has lost 87 percent of that water to space. Credit: NASA/GSFC
The young planet would have had enough water to cover the entire surface in a liquid layer about 450 feet (137 meters) deep. More likely, the water would have formed an ocean occupying almost half of Mars’ northern hemisphere, in some regions reaching depths greater than a mile (1.6 kilometers).

“Our study provides a solid estimate of how much water Mars once had, by determining how much water was lost to space,” said Geronimo Villanueva, first author of the paper and scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “With this work, we can better understand the history of water on Mars.”

The new estimate is based on detailed observations of two slightly different forms of water in Mars’ atmosphere. One is the familiar H2O, made with two hydrogens and one oxygen. The other is HDO, a naturally occurring variation in which one hydrogen is replaced by a heavier form, called deuterium.

Continue reading “​Mars Lost an Ocean’s Worth of Water”

Ares and Antares

Over the next few days the planet Mars will pass the bright star Antares. The two appear so similar in color and magnitude that the star’s name derives from Mars… The name Antares is from Anti-Ares or opposite of Mars. Recalling that the Greek name for the god of war Mars was Ares.

These two will appear close for several days, passing closest on the September 27th at a distance of 3.1°. Mars will be shining brightly at magnitude 0.8 while Antares will be very slightly dimmer at 1.1, almost too close to differentiate. The coloration is also quite close, a ruddy orange, making the two almost indistinguishable. Mars will be the one to the west. Both will be easily visible in the south after sunset.

The Moon and Mars

Tonight the Moon will be close to Mars. The pair will be obvious at sunset, having risen mid-afternoon. Look for the bright planet just 3° north of the Moon. Just a month after opposition the planet is still quite bright, shining at magnitude -0.9 and notably orange in color. The star Spica is about the same magnitude and visible 15° east of the Moon.

A Starry Dawn over Mauna Loa

A photograph of serendipity.

The photograph was planned… Somewhat. I knew there were some picturesque trees on the lava field along Saddle road. The plan was to shoot one of these trees silhouetted against the Milky Way and Mauna Loa. That was the plan. At least until the plan met reality.

Shot as planned the results were less than stellar. Actually they were rather boring. The rising summer Milky Way was spectacular, nothing else worked. The enormous bulk of Mauna Loa became a bump on the horizon from the low angle with the 14mm lens. The trees did not look like much against the dark.

Serendipity intervened… First a passing car lit the trees with dramatic results. Car headlights caught the trees at just the right angle to light up the right bits, a lucky bit of geometry and road alignment. Looking at the image on my screen I was intrigued… I repositioned the camera and shot again when another vehicle passed… This was working!

As I waited for other passing cars the shots deteriorated, odd glows across the frame. Were the headlights catching the big dome of glass at the front of the lens? Blocking the light from the headlights on the camera did not help. I pull out a flashlight to check the camera… Ack! The lens was fogging up!

Retrieving the anti-dew kit and a battery from the vehicle I secured a dew strap around the camera lens. At this point I wanted the shot and was willing to work for it. I was lucky again… I had thrown the dew gear in the car as a last moment afterthought.

It took time for the lens to warm and clear. As I waited dawn crept into the sky. I took a last few shots as the light increased and the stars faded. The dawn light added a nice shade of blue to the sky with a hint of peach to one side, another serendipitous bit that added to the photo. A last wisp of fog on the lens was just enough to create halos around Mars and the brighter stars.

Not a bad result! With a little skill and more than a little luck. The shot has been entered in the Hawai’i Photo Expo. Hopefully the jurors think the shot is as good as I think it is.

Milky Way Dawn over Mauna Loa
The rising summer Milky Way, Mars and dawn over Mauna Loa

The Moon, Mercury, Mars and Jupiter

The dawn is getting crowded. While three planets, Mercury, Mars and Jupiter have been dancing on the dawn stage for weeks now, tomorrow morning a thin crescent, waning Moon will join in. Tomorrow morning the Moon will be 10% illuminated and 4.5° south of Jupiter.

Over the next couple mornings the Moon will continue to wane and slide along the line of planets in the dawn. On the morning of the 4th it will be 5% illuminated and between Mercury and Mars. On the 5th it will be lower than all three and only 1.6% illuminated.

Mars and Jupiter

Mercury, Venus and Jupiter
An evening conjunction of Mercury, Venus and Jupiter on 30 May, 2013
Tomorrow morning and Monday morning will see a close pairing of Mars and Jupiter. While the two have been moving closer for a few days, during these two dawns the separation will be just under a degree.

Look for the pair to rise about 4:13am, almost two hours before the Sun. The two planets will be 20 degrees above the horizon at sunrise. They should be easy to spot with Jupiter at -2 magnitude and Mars dimmer but still easy at 1.5 magnitude. Look 8° below the pair for Mercury still rising towards maximum elongation.

Mars and Jupiter

Over the next few mornings Mars and Jupiter will rendezvous in the dawn sky. This morning sees the two a little over 2° apart. Over the next few days that will narrow quickly with close approach occurring on the mornings of July 21st and 22nd with about 50′ of separation between the two planets. By the 26th the distance between the pair will again have grown to over 2°.

Throughout the encounter the two planets will precede the Sun by about 25°, rising about 04:00HST, well placed for observation.

Keep an eye out for Mercury below the pairing, a 2nd magnitude object about halfway between the conjunction and the rising Sun. The innermost planet will reach maximum elongation on July 29th.

The mornings of August 3rd and 4th will see a thin crescent Moon slide along the line of three planets in the dawn.