The Moon, Venus and Mars

The Moon, Venus and Jupiter
A morning conjunction of the three brightest objects in the night sky, the Moon, Venus and Jupiter on the morning of July 15, 2012, the Pleiades star cluster can be seen at the top
This evening a pretty crescent Moon will slide past Venus and Mars in the sunset. The Moon will be a slim 16% crescent a little over 5° from Venus shining at -4.6 magnitude.

Look for the trio in the western sky this evening just after sunset, it will be nearly impossible to overlook. You have plenty of time to enjoy the show as the trio will not set until around 9:30pm.

The Moon, Venus and Mars

The Moon, Venus and Jupiter
A morning conjunction of the three brightest objects in the night sky, the Moon, Venus and Jupiter on the morning of July 15, 2012, the Pleiades star cluster can be seen at the top
This evening a pretty crescent Moon will be located close to a brilliant Venus. The Moon will be a slim 9% crescent a little over 11° from Venus shining at -4.6 magnitude.

The Moon is approaching the pair of Venus and Mars, tomorrow will see the trio in close proximity, forming a triangle of about 5° separation.

Venus and Mars

The Moon, Venus and Jupiter
A morning conjunction of the three brightest objects in the night sky, the Moon, Venus and Jupiter on the morning of July 15, 2012, the Pleiades star cluster can be seen at the top
Over the coming weeks Venus and Mars will dance in the sunset. Close approach will occur on February 2nd, with the pair about 5° apart. They will remain in close proximity in the sky for much of February, finally disappearing into the glare of sunset around the end of the month.

On the evening of the 31st, a pretty crescent Moon will join this dance in the sunset, forming a triangle about 5° across. A 16% illuminated crescent moon with make a lovely trio with the bright planets.

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.

Conjunction
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.