Sun keeps close company with the planets / New color maps of Saturn’s moons

Although not an official conjunction, three planets and the Moon are grouped within about 10 degrees of the Sun today. Except for the Moon, which will move on into the evening sky, the planets will be near the Sun the next few days. Stellarium

Hidden by sunlight today, the New Moon and three planets parade across the sky in the constellations Libra and Scorpius. It’s a big celestial gathering and one of the reasons few planets are visible in the evening sky this month — they’re all too close to the Sun.

Hanging like a dewdrop from a blade of grass, Saturn’s moon Tethys (TEE-thiss) is about 660 miles (1062 km) across and made of mostly ice. The narrow F-ring and wider A-ring cross in front of the moon in this image released last month and taken by the Cassini spacecraft. Credit: NASA/JPL-Caltech/Space Science Institute

Mars escapes the glare and so does Jupiter, which comes up in the east like a spark yellow fire around 11 o’clock. Saturn, east of the Sun, is now in the morning sky though still lost in the solar glare. Let’s stop by that planet and its largest moons today and look at some brand new maps made with NASA’s Cassini orbiter.

Color map of Enceladus. The yellow and magenta colors show differences in the depth of surface deposits. The blue “tiger stripes” in the southern hemisphere, where the moon vents water vapor and other material as geysers, show brightly in ultraviolet light. Researchers think it might be due to large-grained ice exposures. Credit: NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute

With its rings and butterscotch clouds, few planets rival Saturn for beauty, but its moons are equally fascinating for their strange colors, textures and alien features. NASA recently released a series of global, color mosaics of six of its largest moons based on 10 years of images taken by NASA’s Cassini spacecraft as it orbited the Saturn system. These are the first global color maps of these moons produced from the Cassini data. The colors are broader than what the human eye sees, extending into the ultraviolet and infrared (beyond red) part of the spectrum. They’re also VERY detailed – just click on any of them for a close-up. I’ve included four of the six. To see them all, click HERE.

Iapetus (eye-APP-eh-tuss) looks very strange with one hemisphere bright and icy and the other covered in about a foot of darker material. Iapetus rotates very slowly – once every 79 days. It’s thought that an impact of a darker object long ago coated part of  its surface, causing that area to absorb more sunlight over the long day. More heat meant more ice vaporized which then re-condensed as frost/ice on the moon’s bright side, further concentrating the darker material. This expanded in a positive feedback loop that eventually led to an ever-whitening hemisphere while the other grew blacker. Credit: NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute

On Tethys, scientists think the dark colors of the moon’s trailing hemisphere are due to changes in ice and minerals caused by bombardment from high-speed particles and radiation in Saturn’s powerful magnetic field. The lighter-colored leading hemisphere is coated with icy dust from Saturn’s E-ring, formed from tiny particles ejected from Enceladus’ south polar geysers. The purplish equatorial band gets its color from high-energy electrons in Saturn’s magnetic field slamming into the moon. Credit: NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute

Meet Dione, a 698-mile-wide moon. Its color variations are believed to be caused by the same factors affecting Tethys – radiation and high-speed particles weathering the trailing hemisphere ice and the effects of icy mist spewed by Enceladus on the leading hemisphere. Credit:  NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute 

Tomorrow’s new moon foretells October’s solar eclipse

Tomorrow July 26, 2014, the invisible new moon will pass a few degrees south of the sun in the daytime sky. Stellarium

New moons aren’t much to look at. You can’t even see them most months of the year. That’s true for tomorrow’s new moon which will invisibly accompany the sun in its journey across the sky.

New moons occur about once a month when the moon passes between the sun and Earth. We can’t see them for two reasons: first, no sunshine touches the Earth-facing side when the moon lies in the same direction as the sun. It’s completely dark. From our perspective, the out-of-view lunar farside gets all the sunlight. Second, since the moon is nearly in line with the sun, it’s utterly lost in the glare of daylight.

The moon seesaws 5 degrees north and south of Earth’s orbit during its monthly cycle because its orbit is tilted with respect to Earth’s. Only when the moon crosses the plane of Earth’s orbit at the same time as a new moon do we see a solar eclipse. Illustration: Bob King

We normally have to wait two days after new moon – when the moon’s orbital motion carries it to the left (east) of the sun – to see it as a thin crescent at dusk.

Most of the time the moon passes north or south of the sun at new phase because its orbit is tilted 5 degrees with respect to Earth’s. But 2.4 times a year on average, new moon coincides with the time the moon’s seesawing path slices through the plane of Earth’s orbit. For a brief time during that crossing, all three bodies are aligned and happy earthlings witness a solar eclipse.

If the alignment is imprecise, the moon blocks only a part of the sun, giving us a partial solar eclipse.  If dead-on, we see a rarer total solar eclipse.

View of the partial solar eclipse across the Upper Midwest a half hour before sunset on October 23. By coincidence, Venus will be near conjunction at the same time and only a couple moon diameters north of the pair. Seeing the planet in a telescope will still be challenging because of daylight glare.  Stellarium

On October 23 this year, the lineup at new moon will be a good if imperfect one with a maximum of 81% of the sun covered. The partial eclipse will be visible across much of North America; from the eastern half of the U.S. and Canada the event will occur near sunset, adding a touch of drama to the scene.

I wrote earlier that we can’t see a new moon. That’s only partly true. We mostly pay attention to the sun’s changing shape during solar eclipses, but the dark, curving bite working its way slowly across the sun’s disk is none other than the new moon seen in silhouette.

Feel young again! – Catch sight of the infant moon tonight

Watch for a very young crescent moon at dusk this evening. It will be less than a day old seen from much of the U.S. This map shows the sky facing southwest about 30 minutes after sunset when the moon will about 5 degrees high seen from mid-northern latitudes. Stellarium

While winds and snow in my neck of the woods guarantee an overcast night, you might be more fortunate. If so, I encourage you to look for a very young and thin lunar crescent at dusk tonight. For U.S. skywatchers the moon will be anywhere from 21.5 hours old (East Coast) to 24.5 hours old (West Coast) and visible between 20-45 minutes after sundown 4-5 degrees high in the southwest.

You can use the planet Venus, now moderately low in the southwestern sky, and the sunset point, where the lingering glow along the western horizon is brightest, to help you pinpoint the moon.

A 24-hour old crescent on May 14, 2010 – one of the youngest moons I’ve ever seen. Credit: Bob King

Not many people get to see a crescent that’s only a day (or less) old and few things in the heavens are as beautiful. The moon looks frail and fragile enough to simply dissolve into the sky – a sight you won’t soon forget. You’ll need an open horizon to the southwest, clear skies and pair of binoculars to fall back on.

As you study the moon in binoculars, you’ll notice right away the skinny arc isn’t smooth but ragged or broken along its length. These seeming breaks are caused by oblique lighting on crater walls and mountain peaks creating shadows long enough to bite into and hide portions of the moon’s edge.

Another very thin crescent on Jan. 5, 2011. Credit: Bob King

While spotting a day-old moon takes a little effort, anything under 20 hours requires careful planning as the moon is that much thinner, closer to the horizon and sets even earlier. The record for youngest moon spotted with the naked eye goes writer and amateur astronomer Steven James O’Meara, who nabbed a 15 hour 32 minute crescent in May 1990.

Theirry Legault’s famous youngest moon ever photographed through his telescopes on July 8, 2013. Click to learn more how he did it. Credit: Thierry Legault

West Coast skywatchers have the opportunity to challenge that record on Jan. 1, 2014. New moon occurs at 3:15 a.m. Pacific Time that day; by sunset (5 p.m.) the crescent will be just 14 hours old fifteen minutes after sunset. Tough one! That’s why it’s OK to cheat using binoculars. The record for youngest moon ever seen with optical aid goes to Mohsen G. Mirsaeed of Tehran on September 7, 2002 at just 11 hours 40 minutes past new.

The ultimate record, which will never be broken, is 0 hours past new. It was set July 8 this year when French astrophotographer Thierry Legault photographed the new moon in the middle of the day. No, he never saw it with his eye; only the camera recorded the unique moment.

NASA’s LADEE probe reaches moon; lunar crescent and Venus pair up at dusk

LADEE will explore the makeup of the moon’s flimsy atmosphere and test a cutting-edge communications system

NASA’s Lunar Atmosphere and Dust Environment Explorer spacecraft (LADEE) safely entered lunar orbit yesterday and will soon test its futuristic laser communications system. The Lunar Laser Communications Demonstration aboard LADEE will link up with ground stations in New Mexico, California and the Canary Islands, sending data packets back to Earth at the rate of hundreds of megabits per second.

A small sample of moon dust collected by the Apollo 17 astronauts looks like black powder. The vial is housed at the Laboratory for Atmospheric and Space Physics in Boulder, Col. Credit: Kevin Baird

After the testing is complete, NASA will lower LADEE’s orbit to begin its 100-day mission measuring the composition of the moon’s extremely tenuous atmosphere, where atoms are so few they never collide. LADEE will also explore the dust environment closer to the surface. Scientists hope to explain what causes the mysterious glow along the sunrise and sunset horizons seen by Apollo astronauts back in the 1960s and 70s. A leading theory holds that dust gets electrostatically levitated after being charged by solar radiation.

The crescent moon pairs up with Venus tonight and tomorrow at dusk. The map shows the sky about a half hour after sunset facing southwest. Created with Stellarium

As the spacecraft begins its mission, we can turn toward the crescent moon, now making its return to the evening sky at dusk. Tonight and tomorrow night it joins Venus – don’t miss the opportunity to see the two brightest nighttime sky objects together against a colorful twilight sky.

Crescent moon shortly before sunrise in the eastern sky on Oct. 2. The horns point up and to the right or west. Credit: Bob King

Every month we get two opposing crescents – one in the evening after sunset, with the crescent’s horns pointing to the left or east, and the other at dawn shaped like the letter “C” with horns pointed west. These two crescent regimes flank either side of the new moon phase, when the moon lies almost directly between the sun and Earth. Except during a solar eclipse, we can’t see a new moon because it’s nearly in the same line of sight as the sun and lost in the glare of day.

Dueling crescent moons are visible on either side of new moon phase when the moon passes between Earth and the sun in its orbit. Illustration: Bob King

A day or two before and after new, the moon lies far enough to one side of the Earth-sun line for its edge to turn into the sunlight. We see a shining crescent. As the moon continues along its orbit, the angle it makes to Earth and sun widens, and its phase waxes from crescent to half to full before returning to morning crescent and new.

With tonight’s crescent a brand new cycle begins. Watching the moon’s changing phases we become more familiar with its orbital motion and spatial relationship to the Earth and sun.

In darkness the moon is reborn

If we could see the moon today, it would be a very thin crescent only a few degrees from the sun. Tomorrow it’s in new moon phase. Maps created with Stellarium

What’s old today but instantly becomes young again tomorrow? If you guessed the moon, you’re right! Today the moon winds up its current cycle of phases as an exceedingly thin crescent so close to the sun it’s invisible in the solar glare.

The moon’s cycle has always been a metaphor for life. Every month it’s born again as a thin crescent in the western evening sky, grows to a half-pie seven days later and reaches its full power and radiance when full at 14 days. After full, the moon’s radiance declines as its phase wanes to last quarter (21 days) and then to a whiskery crescent at dawn. Before it finally disappears in the sun’s glare, the moon, now 28 days old, reaches the end of its “life” cycle. But only briefly. The very next day, moments after new moon phase, it’s reborn again as an evening crescent.

When we run into troubles in our lives, we might look to the ever-renewing moon for inspiration.

The sky looking west-southwest a half hour after sunset Monday evening Feb. 11, 2013. You might be able to spot dimmer Mars in binoculars.

Tomorrow morning at 2:20 a.m. (CST) the moon will be exactly lined up with the sun and pass through new moon phase. Skywatchers in the western hemisphere won’t see the moon either day because it’s in the same direction as the sun and swamped by glare.

By Monday Feb. 11 however, the moon’s orbital motion will remove it far enough from the sun to be visible during evening twilight.  And there’s a bonus. The crescent will float a few degrees above the planet Mercury.

I’ve removed the atmosphere in this illustration so you can see where the moon is today at noon (CST), tomorrow morning when it reaches new moon phase and tomorrow Feb. 10 at noon. It passes north of the sun, which is in the constellation Capricornus. Notice all the planets in the neighborhood.

If we were to follow the moon today through new moon and into tomorrow, we’d notice it passes well north of the sun. Most of the time, the new moon is either north or south of the sun because its orbit is tipped about 5 degrees relative to Earth’s orbit.

The moon’s tilted orbit causes it to swing north or south (pictured here) of the sun from Earth’s perspective. A couple times a year however it crosses directly in front and a total solar eclipse is visible from somewhere on Earth. Illustration: Bob King

Over the course of its monthly cycle, it bobs up and then down along its tilted orbit. But 2 or 3 times a year, when the moon intersects the plane of Earth’s orbit at the same time as new moon phase, it crosses directly in front of the sun and we see a total solar eclipse. In fact, this is the only time we can see a new moon with the naked eye. It looks exactly like what you’d expect – a blank, black disk scrubbed free of its past life, waiting to begin the next as a tender crescent.

The new moon – black disk – is plainly visible silhouetting the sun during a total solar eclipse. Credit: Luc Viatour

The sun’s forever blowing bubbles

A huge bubble of high speed solar wind called a coronal mass ejection or CME leaves the sun at many miles per second yesterday morning July 17. Click photo to see a movie. Photo taken by SOHO’s C3 coronagraph. Credit: NASA’/ESA

Yesterday around 11 o’clock my wife and I were driving to Minneapolis to help move our older daughter. Little did we know that when we stopped to pick up pastries along the highway, the sunspot group that delighted us with auroras last week had just unleashed another significant flare. As we paid the clerk and walked out the door, the coronal mass ejection from the explosion was already ballooning Earth’s way.

Because the bubble is off to one side of the sun and not directly aimed at our planet, the blizzard of electrons and protons will only graze us. A small chance of auroras is possible when it arrives on Friday July 20.

The sky this evening, with the atmosphere removed, so you can see the position of the sun in Gemini and the moon just a few degrees below it. In New Moon phase, we can’t see the moon because it’s too close to sun and invisible in the glare of day. Created with Stellarium

Not far from the sun in the sky a much quieter event is happening. The moon will be in New Moon phase at 11:24 p.m. (CDT) tonight July 18.

If the sun, moon and Earth were exactly lined up in that order, we’d see a total eclipse of the sun, but because the moon’s orbit is tipped relative to Earth’s, it passes a few degrees south of the sun tonight. At other new moons, it passes to the north.

No one gets to see a new moon because it’s much too close to the sun and completely invisible in the solar glare. During a solar eclipse like this past May’s, many of us got to see our first new moon in years as its black silhouette carved the sun into a thick crescent.

Nova Sagittarii #4 photographed on July 16. Thanks and credit to: Bill Gucfa

Nova watchers – not the TV show, but that’s worth watching too – I’ve got good news for you. You can still catch Nova Sagittarii #4 in a small telescope. You might recall that this “new star” was discovered by Japanese amateurs earlier this month in the Teapot constellation Sagittarius.

It’s shining at about magnitude 9.0 and visible in any small scope. You can use the charts from my earlier blog and the photo at left to help you find it. I’ve added magnitudes from the AAVSO (American Assn. of Variable Star Observers) to Bill’s photo if you’d like to estimate the nova’s brightness on your own.

Venus returns at dusk and how water helped us to see

Venus is not easy to find but with a good horizon and determination you will succeed. The map shows the planet as seen from mid-northern latitudes about 15 minutes after sunset this evening. Mercury will require binoculars. Created with Stellarium

If you’ve been pining for Venus, the goddess of beauty, your days of anguish will soon be ending. Venus has returned to the evening sky after a long daytime engagement with the sun. Put plainly, it’s been too near the sun to observe, but beginning now and continuing for the remainder of the year, the brightest planet will part ways with the keeper of the light and inch its way into the night.

Venus won’t easy … at first. Tonight it will be visible for a brief time starting about 15 minutes after sunset. Look very low in the southwestern sky some 3 degrees above the horizon a little more than one outstretched fist to the left of the sun. Binoculars will help you spot this single bright “star”. If your skies are very transparent, you might even get to see Mercury just 2 degrees below Venus and very close to setting. Over the next few evenings, Venus and Mercury will remain near one another and remain a challenging duo. Of course, if you live in the southern U.S., the two planets are tipped are at a steeper angle to the horizon and noticeably easier to see.Come November, Venus will set later and gradually become easier to see.

The lunar crescent -- just 2 1/2 days before new -- cuts a sharp figure in the sky before sunrise this morning. Photo: Bob King

My daughter came up to visit from college over the weekend. She always marvels at how dark it is where we live and how many stars she can see compared to the Big City. When I helped her scrape frost from her car windows early this morning, the waning crescent moon sent us a small smile. There are only two days left to see the moon at dawn before it new moon on the 26th and its return as a crescent in the evening sky.

Dewdrops not only focus the sun into tiny bright images, they also magnify the veins of the leaf. Photo: Bob King

The other morning while dashing off to work, I was stopped by the sight of a dew-dabbed leaf in my front yard. Looking closely, you can see how the curved surfaces of the drops act like the curved lenses in a pair of glasses, binoculars or telescope to focus the sun’s image into tiny brilliant spots on the leaf’s surface. The convex drops also serve as ephemeral magnifying glasses, too. Take a look at the enlarged view of the leaf vein under the second drop to the left of the big one at top.

I wonder if raindrops or dewdrops were our ancestor’s first inspiration for using rounded, clear objects to magnify, focus and clarify both distant and nearby scenes. While raindrops aren’t very handy when you need a lens, the same principle of curved surfaces can be applied to glass-making, an art discovered around 5000 B.C. The earliest known lens to currently be unearthed was made in the year 750 B.C. and found at the Assyrian palace of Nimrud in modern-day Iraq. It’s believed to have been used as a  magnifying glass or as a burning-glass to start fires.

The infamous Nero, who become Roman Emporer in 54 A.D., watched gladiator fights through a monocle apparently made of emerald crystal. It’s unclear if it was ground out to correct nearsightedness or if he simply was following a popular belief at the time that vision is improved and refreshed when seen through the green gem.

Reading stone from the Middle Ages

During the same era, glass globes filled with water were used to magnify written documents to make them more legible to those like me whose near-vision declines with age. Later, hemisphere-shaped glass lenses called reading stones were used to magnify text for easier reading. Around 1284, the Italian Salvino D’Armate is credited with inventing the first wearable pair of eyeglasses. More than 300 years would pass before Dutch spectacle makers in the late 16th century would place two different lenses one behind the other to create the first telescope.

In researching this information, I came across a fascinating early reference to a telescope from the works of Roger Bacon, the English philosopher and Franciscan friar who was one to advocate the modern scientific method as a tool to understand the world.

This from his Opus Majus: “For we can so shape transparent bodies, and arrange them in such a way with respect to our sight and objects of vision, that the rays will be reflected and bent in any direction we desire, and under any angle we wish, we may see the object near or at a distance … So we might also cause the Sun, Moon and stars in appearance to descend here below.”

And that was in the year 1268!