spaceplasma:

Galileo view of an Earth-Moon conjunction

As Galileo receded from its second flyby of Earth on December 16 and 17, 1992, it captured this sequence of Earth rotating as the Moon zipped by on its orbit. There are 56 frames in total, each separated by 15 minutes, spanning about 14 hours.

Credit: NASA / JPL / Doug Ellison

NASA’s Mars Spacecraft Go Solo Next Month

An unfavorable planetary alignment will force NASA’s fleet of robotic Mars explorers to be a lot more self-sufficient next month.

Mission controllers won’t send any commands to the agency’s various Mars spacecraft for much of April, because the sun will lie between Earth and the Red Planet during that time. Our star can disrupt and degrade interplanetary communications in such an alignment, which is known as a Mars solar conjunction, so spacecraft handlers won’t take any chances.

“Receiving a partial command could confuse the spacecraft, putting them in grave danger,” NASA officials explain in a video posted Tuesday (March 19) by the agency’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

Transmissions from Earth to the Mars rover Curiosity are slated to be suspended from April 4 to May 1, officials said. No commands will be sent to Curiosity’s older rover cousin Opportunity or NASA’s Mars-orbiting craft — Mars Odyssey and the Mars Reconnaissance Orbiter (MRO) — from April 9 to April 26.

Both rovers will continue to do stationary science work throughout the conjunction period, relying on commands sent up to them beforehand.

“We are doing extra science planning work this month to develop almost three weeks of activity sequences for Opportunity to execute throughout conjunction,” Opportunity mission manager Alfonso Herrera of JPL said in a statement.

MRO and Mars Odyssey will continue science observations as well, though on a more limited basis. The orbiters will also continue their role as rover communication links, receiving data from Opportunity and Curiosity.

Odyssey will send information — its own observations and the rovers’ data — Earthward throughout the conjunction period, though the mission team anticipates some dropouts, so Odyssey will send the data again later as needed.

MRO will take a different tack, storing everything from April 4 until after conjunction. The spacecraft’s operators estimate it will have about 52 gigabits of data onboard when it’s cleared to transmit to Earth again on May 1.

Mars solar conjunctions occur every 26 months, so all of the spacecraft have dealt with them except Curiosity, which landed on the Red Planet last August. Opportunity has been through five conjunctions since arriving on Mars in January 2004, but Odyssey is even more experienced.

“This is our sixth conjunction for Odyssey,” Chris Potts of JPL said in a statement. Potts is mission manager for Odyssey, which has been orbiting Mars since 2001. “We have plenty of useful experience dealing with them, though each conjunction is a little different.”

Mercury’s False Moon: The Mercury/Mars Planetary Conjunction this Weekend

image 1: Looking west 30 minutes after sunset on Feb. 8th from latitude 30° north.
image 2: Mercury (lower center) & Mars (upper center) imaged by Mike Weasner on February 5th.
image 3: Mercury and Mars on February 8, 2013. See how close they’ll be? Image credit: Stellarium

The history of astronomy is littered with astronomical objects in the solar system that have fallen to the wayside. These include fleeting sightings of Venusian moons, inter-mercurial planets, and even secondary moons of the Earth.

While none of these observations ever amounted to true discoveries, this weekend gives observers and astrophotographers a unique chance to “mimic” a spurious discovery that has dotted astronomical lore: a visual “pseudo-moon” for the planet Mercury. This “moon illusion” will occur on February 8, 2013 during the closest conjunction of two naked eye planets in 2013. February offers a chance to see the fleeting Mercury in the sky, and this conjunction with Mars will provide the opportunity to see how Mercury would look in the night sky if it had a moon!

Mercury has been suspected of having moons before. On March 29th 1974, the Mariner 10 spacecraft became the first mission to image the innermost world up close. Mariner 10 mapped 40-45% of Mercury on 3 successive passes, revealing a pock-marked world not that different than our own Moon. But Mariner 10 also detected something more: brief anomalies in the ultra-violet spectrum suggestive of a moon with a 3 day period. For a very brief time, Mercury was thought to have a moon of its own, and NASA nearly made a press release to this effect. The spectroscopic binary 31 Crateris is now suspect in the anomalous readings. Still, the Mariner 10 observation made researchers realize the observations in the extreme UV were possible over interstellar distances.

Today, NASA has a permanent emissary orbiting Mercury with its MESSENGER spacecraft. MESSENGER first entered orbit around Mercury on March 18th, 2011 after a series of trajectory changing flybys. MESSENGER has filled in the map of the remainder of Mercury’s surface, with no signs of the anomalous “moon.” Interestingly, MESSENGER was also on the lookout for “Vulcanoids” (tiny asteroids interior to Mercury’s orbit; sorry, Mr. Spock) while enroute to its final orbital insertion. NASA even released an April Fool’s Day prank of a fake “discovery” of a Mercurial moon dubbed Caduceus in 2012.

But MESSENGER has made some fascinating true to life discoveries, such as sampling Mercury’s tenuous exosphere & the possibility of ice at its permanently shadowed poles. Lots of new features have been mapped and named on Mercury, following the convention of naming features after famous deceased artists, musicians and authors set forth by the International Astronomical Union. It’s amazing to think that we had no detailed views at the entire surface of Mercury until the 1970’s, although some ground-based professional observatories and even skilled amateurs are now doing just that.

Fast forward to this weekend. Mercury is just beginning its first apparition of six in 2013 this week and is currently visible low in the dusk sky after sunset to the west. Mercury reaches greatest eastern elongation on February 16th at 18.1° from the Sun. Interestingly, that’s very close to the shortest elongation that can occur. Mercury’s orbit is eccentric enough that greatest elongation as seen from the Earth can vary from 17.9° to 27.8°. This month’s elongation happens within only 5 hours of Mercury reaching perihelion at 46 million kilometers from the Sun. This means that Mercury won’t peak above the dusk horizon for mid-northern latitude observers quite as high as it will during the next evening apparition of the planet in June.

This appearance of Mercury does, however, have some things going for it. First off, the ecliptic sits at a favorable viewing angle, roughly perpendicular to the western horizon at dusk for mid- to high northern latitude observers. This gives Mercury a bit of a “boost” out of the weeds. Secondly, Mercury is a full magnitude (2.512 times) brighter when it reaches maximum elongation near perihelion than aphelion, such as its next appearance in the dawn sky on March 31st of this year. Mercury will reach magnitude -0.5, versus +0.5 in late March.

To see Mercury, find a site with a western horizon free of ground clutter and start sweeping the horizon with binoculars about 15 minutes after local sunset. See a reddish dot just above Mercury? That’s the planet Mars, shining about 7 times fainter than -1.0 magnitude Mercury at magnitude +1.2. Mercury is fast approaching a conjunction with Mars; the two will be only 15’ apart (half the average width of a Full Moon) on the evening of February 8th at 17:00 Universal Time!

If you ever wondered how Mercury would appear with a moon, now is a good time to take a look! Again, binoculars are the best optical tool for the job. Can you see both with the naked eye? Can you place both in the same low power field of view with a telescope? You’ll only have a 15-30 minute window (depending on latitude) to snare the pairing before they follow the setting Sun below the horizon. Photographing the pair will be tricky, though not impossible, as they present a very low contrast against the bright background twilight sky.

Don’t expect to see detail on Mercury or Mars telescopically; Mercury only appears 5.8” across on the 8th, while Mars is 4” in apparent size. Mars disappears from view later this month to reach solar conjunction on April 18th 2013. The waxing crescent Moon just 1 day after New joins the pair on the evenings of February 10th and 11th.

Now for the “Wow” factor of what you’re seeing. The conjunction of Mars and Mercury only appears close; in reality, they are over 180 million kilometers apart. Mercury is 1.15 Astronomical Units (A.U.s)/178 million kilometers from us on February 8th, while Mars is nearly at its farthest from us at 2.31 A.U.s/358 million kilometers distant. It’s splendid to think that with Curiosity and friends operating on Mars and Messenger orbiting Mercury, we now have permanent robotic “eyes” on and around both!

Credits: Simulation created by the author using Starry Night.

quantumreverie:

In this picture: the Moon, Callisto (hidden), Europa, Jupiter, Io, and Ganymede

abcstarstuff:

Christmas Sky Show

Just when you thought Christmas was over: At the end of the day on Dec. 25th, a pair of holiday lights will pop out of the deepening twilight. Jupiter and the Moon are having a Christmas conjunction.

It’s a beautiful apparition, visible all around the globe.

Even city dwellers, who often miss astronomical events because of light pollution, can
For anyone who gets a telescope for Christmas, the timing is perfect.

Jupiter and the Moon are among the most satisfying targets for backyard optics.

A quick sweep of the telescope from Jupiter to the Moon and back again will reveal Jupiter’s storms and cloud belts, the Moon’s mountains and impact craters, and of course the four Galilean satellites circling the giant planet like a miniature solar system.

Jupiter’s trademark Great Red Spot will also be on display—and it is worth a look. Astronomers recently announced that the enormous swirling storm, twice as wide as the planet Earth, is “spinning up.”

Actually, explains planetary scientist Glenn Orton of NASA’s Jet Propulsion Laboratory, “the Red Spot is shrinking.” He likens it to “the iconic picture of a figure skater pulling her arms in to spin faster. As the size contracts, the spin rate increases.”

John Rogers, head of the British Astronomical Association’s Jupiter Section, noticed the phenomenon in recent pictures of Jupiter snapped by amateur astronomers. He was able to track a dark cloudy feature as it swirled three times around the Red Spot’s central vortex. The circulating streak completed the circuit in only 4.0 days, shorter than the 4.5 days Rogers measured in 2006 using the same method.

Looking back in time, “the trend of decreasing rotation period has been consistent at least since Voyager visited Jupiter in 1979,” says Rogers. As the spot shrinks, it also changes shape. Decades ago the Red Spot looked like a sausage – now it’s more circular.

What happens next is hard to say. “Perhaps the Red Spot will continue to shrink and eventually disappear,” speculates Rogers. “Or perhaps it will be rejuvenated if some new storm arises to reinforce it.”

One thing is certain, Christmas night is a good time to look. The Red Spot will be transiting Jupiter’s middle for observers across North America and will be perfectly positioned for telescopic observations.

But you don’t need a telescope to enjoy the show. Step outside at sunset on Dec. 25th and look east. After all, Christmas isn’t really over until you’ve seen the holiday lights.

The gas giant and Earth’s Moon will provide some holiday lights in the eastern sky on December 25th, 2012 (at sunset). Seen through a telescope, Jupiter’s great red spot and its moons will be visible as well.

ikenbot:

A Different Horizon

The Jupiter-Moon conjunction as seen from the moon’s horizon.

(Source: kenobi-wan-obi)

ikenbot:

Venus-Jupiter Close Conjunction by Laurent Laveder (France)

(Source: kenobi-wan-obi)

thescienceofreality:

Conjunction Colours - APOD
Image Credit & Copyright: Phil Hart

“During the past week, nightfall on planet Earth has featured Mars, Saturn, and Spica in a lovely conjunction near the western horizon. Still forming the corners of a distinctive celestial triangle after sunset and recently joined by a crescent Moon, they are all about the same brightness but can exhibit different colors to the discerning eye. This ingenious star trail image was recorded as the trio set on August 12 with a telephoto lens from the shores of Lake Eppalock, in central Victoria, Australia. Focused on foreground eucalyptus trees, the image slightly blurs the trails to show more saturated colors. Can you guess which trail is which? Of course the reddest trail is Mars, with Saturn on the right a paler echo of the Red Planet’s hue. Left is hot and luminousSpica, bluish alpha star of the constellation Virgo.”

thescienceofreality:

Lunar and Planetary Conjunction on August 22, 2012

“Last night — if you were in a good location — the Moon, Spica, Mars, Saturn all came together in a lunar/planetary/stellar conjunction. My attempts to see it and capture i

t failed because of trees (the conjunction took place low on the horizon), but thank goodness for our astrophotographer friends! John Chumack caught the event from his observatory in Ohio (his specs: Canon Rebel Xsi 85mm Lens at F5.6, ISO 400, 1 second exposure) and Ian Musgrave captured the view in Australia, below.”

[Via Universe Today]

fyeahuniverse:

Celestial Conjunction at Paranal (x)

(Source: throughascientificlens, via likeaphysicist)

ikenbot:

Conjunction of the Moon and Jupiter

(Source: kenobi-wan-obi, via wildlydistorted)

discoverynews:

Saturn, Moon, Star to Offer Triple Night Sky Treat

The conjunction offers a chance to see how quickly the moon moves from night to night.

Look toward the southeast on Thursday night (THAT’S TONIGHT!!) about an hour after sunset, and you will behold a rare and beautiful sight, a triple conjunction of the moon, the planet Saturn, and the bright star Spica.

A conjunction occurs when two or more astronomical objects are close together in the sky. In reality they are far apart in space; their closeness is just an effect of perspective. In astrology such close encounters are supposed to cause serious effects, but astronomers know that conjunctions are nothing more than a beautiful sight and a photo opportunity.

keep reading

So far, 2012 has brought us a plethora of planetary conjunctions, with Venus pairing with the Moon, Jupiter and the Pleiades. Not all at the same time, of course, but photographer Patrick Cullis has put them all together in this wonderful timelapse mashup video, which includes the beautiful foreground of the Flatirons of Boulder, CO. “Jupiter and Venus dominated the early days of March, coming within 3 degrees of one another,” writes Patrick. “Then, Venus passed a crescent moon on its way to a meeting with the Seven Sisters, also known as the Pleiades.”

And we’re all waiting for this year’s big conjunction on June 5 or 6, 2012, depending on your location, then the tiny disk of Venus will glide across the face of the Sun. That won’t happen again until 2117.

To complete our conjunction mashup, we’ve got a really unique image, below, of a triple conjunction between 3 different objects, Venus, The Pleiades and an airplane taken on April 4, sent to us by Shahrin Ahmad in Malaysia, PLUS, a wonderful new poem by space’s poet laureate, Stuart Atkinson, about his experiences viewing the recent conjunctions. It’s a must read for any amateur astronomer, putting to words the joys — and disappointments — of lifting your eyes to the heavens!

CONJUNCTION

By Stuart Atkinson

For weeks I watched them drift towards each other,
Approaching shyly, slyly; two would-be lovers
From a Jane Austen dance, casting furtive glances
Across the ballroom of the golden twilight,
Eyes for no-one else as nightfall drew near.
Venus – lovely and lantern-bright, out-shining
Every other dancer on the floor; Jupiter – fainter
By far but still beaming with a noble light,
Stalking his pretty planetary prey…

The first time I saw them they were still
A third-of-the-sky apart,
But each blazing Turner sunset brought them closer yet,
Each day’s end a little better-placed to gaze
Upon each other’s radiant face,
And a million Earthbound eyes looked on, amazed
To see two such fine celestial jewels
Coming together in the sky.
Some sought out a sheltered, grassy place
Of peace and dark to watch the twin sparks’
Close approach in groups; others stood alone
In overgrown gardens or on concrete roofs,
Marvelling at the view from their light-polluted
Homes, wondering what they would see if only
They could escape the Bright and find a place
Without the blinding security lights’ flares
And streetlights’ orange glare…

Of course, I missed the breathless climax
Of their brief encounter. For half a dozen days
Either side of that ringed-in-red date
My sky was thick with cloud fat and foul,
A star- and planet-hiding shroud draped o’er
The Auld Grey Town that was not pulled away
Until the planet parade had passed by,
And the next time I looked to the west
The best view had come and gone:
Unseen by me, Venus and Jupiter had chastely
Touched fingers then parted, leaving
The lovesick gas giant fading, falling
Forlornly towards the rooftops and trees
While the Goddess of Love soared higher,
Growing ever-brighter as she climbed…

Cheated? Yes. But I have fine memories
Of some magical nights, and a hundred photographs,
Taken from the shores of moonlit, duck-dotted lakes
And crumbling castle walls. Sometimes in company,
More usually alone I stood and watched those distant
Worlds waltzing across the western sky,
My so-often-now world weary eyes
Suddenly wide again with wonder at the beauty of it all,
Listening to them calling “Look at us! See
How gloriously we shine above your sleepy little town…!”

…Far apart now, their dusky dalliance a thing of the past,
Venus and Jupiter are just bright stars once more;
The night sky’s restless showbiz spotlight has swept on,
Picking out Saturn, Mars and a waning Moon,
The Great Conjunction relegated
To Celestial Celebrity Has Been history.

Which is how it should be.

The Earth turns, and turns, and turns, setting a universe
Of stars and planets wheeling around pale Polaris,
Lovely and sentinel-still,
While the Milky Way floats serenely
Through her snow-globe of glitter-flake galaxies,
The prickling breeze of a billion billion suns’ solar winds
Blowing on the faces of the few evolved apes
Brave enough to lift their eyes from the grey
Landscapes of their everyday lives and catch
A fleeting glimpse of beauty in the Great Beyond…

© Stuart Atkinson 2012