Feel the bliss, don’t miss Thursday’s partial solar eclipse

The solar crescents show how much Sun will be covered at maximum for various locations across the U.S. and Canada during the October 23rd (Thursday) partial solar eclipse. Credit: Jay Anderson

Doing anything Thursday afternoon? Have a few minutes to spareThere’s a partial eclipse of the Sun visible across much of North America and of Mexico you might like to catch. For observers in the U.S. and Canadian West the whole event begins and ends in the afternoon before sunset. Those living east of the Great Plains will see the Sun set while still in eclipse.

During a solar eclipse, the orbiting Moon passes between the Sun and Earth, completely blocking the Sun from view as shown here. In Thursday’s eclipse, the moon will pass a little north of a line connecting the three orbs, leaving a portion of the Sun uncovered. To view a partial solar eclipse, a safe solar filter is necessary. Credit: Wikipedia

Solar eclipses occur when the Moon glides between the Earth and the Sun, temporarily blocking it from view. Total solar eclipses get most of the attention because the Earth- Moon-Sun alignment is perfect. Like a snug lid on a pot, the Moon blanks out the Sun completely to create a dramatic spectacle of a black, fire-rimmed disk set in a plush solar corona.

Partial eclipses happen because the Moon’s orbit is tipped a few degrees to the Sun-Earth line. Most months, it passes north or south of the Sun and misses it completely. But during a partial eclipse, the Moon’s close enough to that line to partially block the Sun from view. Unlike a total eclipse, all phases of a partial eclipse are unsafe to view unless you use a safe solar filter or view it indirectly via projection.

Map showing times and percentage of the Sun covered during Thursday’s partial solar eclipse. Times are Pacific Daylight – add 1 hour for MDT, 2 hours for CDT and 3 hours for EDT. Interpolate between the lines to find your approximate viewing time. The arc marked A shows where the eclipse begins at sunset; B = Maximum eclipse at sunset and C = Eclipse ends at sunset. Credit: NASA, F. Espenak,with additions by Bob King

As you can see from the map, nowhere will this eclipse be total. Maximum coverage will happen in Nunavut Territory in northern Canada where the musk oxen might catch sight of a fat solar crescent 81% covered by the moon at sunset. The farther north you live in the U.S. or Canada, the deeper the eclipse. Northern U.S. states will see around 60% covered compared to 40% in the deep south.

In Duluth, Minn. for example, the eclipse begins at 4:21 p.m., reaches a maximum of about 65% at 5:33 p.m. and continues into sunset at 6:06 p.m. Since the sun will be low in the western sky from many locations, be sure to get a spot with a wide open view in that direction.To find out times and coverage for your city, use these links:

* U.S. Cities
* Cities in Canada and Mexico 

Some of the different kinds of safe solar filters available. They work by reflecting or absorbing most of the light from the Sun, allowing only a fraction through to the eyes. NEVER LOOK DIRECTLY AT THE SUN without one. Click photos for a supplier of eclipse glasses. Credit: Bob King

Solar filters come in a variety of styles from inexpensive eclipse glasses that use an optical polymer to glass welder’s filters to caps you place over the front end of a telescope. It’s important to use the correct kind – don’t stack a bunch of sunglasses and figure “it’ll do” or look through smoked glass. They still allow dangerous UV and infrared light to pass through and will mess up your retinas for life.

Because we’re on the heels of the eclipse, if you don’t already have a pair of eclipse glasses I recommend a #14 welder’s glass. It’s my favorite actually because it’s easy to stuff in a pocket and heavy-duty enough to take a few dings. You can pick one up for a few dollars at a welding supply shop. Only buy a #14 – lower numbers won’t cut it.

A piece of aluminum foil, a pin and a cardboard box are all you need to build a pinhole projector. The tiny hole creates a small image of the eclipsed Sun inside the darkened box which you place over your head. Remember to look at the projection of the sun on the inner wall of the box – not through the pinhole itself.

Projection provides a fine alternative to using a filter. You can mount a pair of binoculars (or small telescope) on a tripod and project the Sun’s image on a sheet of white paper or build your own pinhole projector using the instructions above.

You can mount binoculars on a tripod, cover one lens with a lenscap and project the sun’s image safely onto a sheet of white cardboard. Credit: Bob King

If leaves still cling to your trees this season, the narrow spaces between the leaves act like natural pinholes and will cast multiple images of the eclipsed Sun on the ground below.

You can even place one hand atop the other and let the sun shine through the gaps between your fingers to see the eclipse. Low tech as it gets, but works in a pinch.

Here are some other things to watch for during the eclipse:

* If you live where half or more of the sun will be covered, you may notice a change in the quality of daylight. To my eye, the light becomes “grayer”. What do you see?

* Telescope users will see the mountains and crater rims along the moon’s edge as tiny bumps and projections against the brilliant solar photosphere. You’ll also notice how much blacker moon is compared to sunspots. Guess what? We’ve got a huge sunspot out there right now – Region 2192. Perfect for comparison!

Partially eclipsed sun just before sunset seen from Island Lake north of Duluth in May 2012. Credit: Bob King

*  Those living where parts of the eclipse happen at sunset will get an extra special view of the sun with a big bite out of it right sitting atop the southwestern horizon.

I wish you excellent weather – good luck!

 

Earth and Mars, space pals forever

This single shot of Earth and Mars together was taken on May 24, 2014 with NASA’s Lunar Reconnaissance Orbiter spacecraft as it orbited the moon. Click to see full, hi-res photo. Credit: NASA/GSFC/Arizona State University

Yesterday we watched the total lunar eclipse from Mercury. Today, NASA’s Lunar Reconnaissance Orbiter (LRO) expands our gaze to encompass both Earth and Mars together in space.

LRO’s viewing post was none other than the moon located 240,000 miles from Earth. On May 24th, instead of staring down at the lunar surface, NASA engineers sent commands to the spacecraft to point its Narrow Angle Camera toward Earth. On that date the two worlds were in conjunction from LRO’s perspective.


Mars and Earth from lunar orbit

Mars was about 70 million miles away (112.5 million km) away at the time or 300 times farther away from the Moon than the Earth. That’s why it’s only a tiny dot in the sky.

Moon-facing hemisphere of Mars on May 8, 2014 seen from lunar orbit. Instruments on LRO sometimes use stars and planets for calibration or other special observations. During one of these off-Moon observations, LROC imaged Mars. The planet is so small in LRO’s camera it could only make out the two larger features shown above. Credit: NASA/GSFC/Arizona State University

I know a commercial photographer who takes pictures of babies when they’re asleep. She has to invest a lot time into each of her photos, much of it spent waiting for the children to fall asleep! Likewise the LRO team. To make sure they got the timing and exposure right, the team practiced on Mars weeks in advance.

Seeing the two planets in the same frame seems to shrink the distance between them and tempt us to shove off from home on an exploratory visit.

The LRO folks put it this way:

“The juxtaposition of Earth and Mars seen from the Moon is a poignant reminder that the Moon would make a convenient waypoint for explorers bound for the fourth planet and beyond! In the near-future, the Moon could serve as a test-bed for construction and resource utilization technologies. Longer-range plans may include the Moon as a resource depot or base of operations for interplanetary activities.”

Ever seen a lunar eclipse from Mercury? Me neither … till now


Wednesday’s lunar eclipse photographed by NASA’s MESSENGER spacecraft at Mercury

As millions of us awoke at dawn and trundled outside to watch the total lunar eclipse this week another set of eyes was keeping tabs from afar. 66 million miles away, NASA’s MESSENGER spacecraft turned its camera toward Earth to capture several images of the moon disappearing into our planet’s shadow. Laced together, they make for a brief but fascinating glimpse of planetary bodies in motion.

Two of the still images showing Earth and moon before and during Wednesday morning’s total eclipse. Credit: NASA

The animation was constructed from 31 images taken two minutes apart from 5:18 to 6:18 a.m. EDT. The images start just before the Moon entered the umbra, the darkest part of the Earth’s shadow.

“From Mercury, the Earth and Moon normally appear as if they were two very bright stars,” noted Hari Nair, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory, in Laurel, Md. “During a lunar eclipse, the Moon seems to disappear during its passage through the Earth’s shadow, as shown in the movie.”

MESSENGER photographed Earth and moon on May 6, 2010 from 114 million miles (183 million km) away. Credit: NASA

Because the moon is so much darker than Earth its brightness has been increased 25 times to show its disappearance more clearly. I’ve included another picture of the Earth and moon against the starry backdrop of deep space also photographed by MESSENGER. Sure puts things in perspective. While not as breathtaking as photos of Earth taken by the Apollo astronauts, seeing our tiny home floating in the void effectively communicates how improbable our existence is. Thank goodness life got a grip and kept it. After 3.5 billion years of evolution the double helix has proven itself a force with which to be reckoned.

The 133-mile-wide double ringed crater Vivaldi captured at sunrise. The low sun highlights valleys and chains of secondary impact craters radiating away from it. Credit: NASA

MESSENGER has been in orbit around Mercury since March 2011 studying the chemical composition of the surface, measuring planet’s magnetic field, mapping polar ices and of course taking pictures. Enjoy a few recent ones.

Hollows on the floor of an unnamed crater on Mercury. Hollows may be areas “eaten away” by the ceaseless bombardment of particles in the solar wind. Or they may form when heat from volcanic activity melts away softer rocks. No one knows for sure. Credit: NASA

How long would it take to drive to the sun?

My old Subaru achieved lunar orbit when the odometer hit 238,000 miles several years back. Credit: Bob King

I spend way too much time in the car, mostly on the job as a photojournalist. Every day, there are places to be at this time and that. Like many who drive around for a living,  I’ve accumulated a few miles on my vehicles.

Once, in an older Subaru, I achieved a one-time dream of reaching the moon. The odometer rolled past the 238,000 mile mark – just under the average lunar distance but easily within perigee range. I would have pushed the vehicle further, but the brakes seized up and soon after I sold the car. I recall it leaving the driveway on a flatbed like a patient being wheeled away to the emergency room.

The sun is some 387 times farther from Earth than the moon. Credit: Bob King

The years of driving it took to “get to the moon” got me wondering how long it would take to drive to the sun, which lies some 93 million miles (150 million km) from Earth or 387 times farther away than the moon.  According to the Guinness Book of World Records, the record vehicle mileage goes to a 1966 Volvo P-1800S with more than  2,850,000 miles (4,586,630 km). Owned by Irvin Gordon of East Patchogue, New York, the car is still driven daily.

A commercial jet flying at 550 mph would need 19 years to reach the sun. Credit: Bob King

While that trashes my record, it’s still only 3% of the way to the sun, a nice start but barely there. Instead, let’s drive non-stop at 60 mph (97 kph). How long would it take before we would complete our journey? An amazingly long time – 177 years. Strange, isn’t it? The sun seems so close because we can feel its warmth and watch it ripen our tomatoes. But it’s out there, w-a-y out there.

Even in a commercial jet flying at 550 mph (885 kph) it would still take 19 years. I’m afraid I just don’t have that kind of time or patience. Even the 5-hour trip to Hawaii from Los Angeles made me twitchy. The Helios probes, the fastest moving space vehicles ever, reached speeds of 157,000 mph as they orbited around the sun sensing the solar wind. At that rate, the sun could be reached in just 24.7 days.


Bill Nye demonstrates the distances between the planets.

How about a planet? Let’s choose picturesque Saturn, now low in the southwestern sky at dusk. Its average distance from the sun is 891 million miles (1.4 billion km) or 1,695 years in a car. That means if we started driving in 320 A.D. when ancient Rome still dominated the western world, we’d finally arrive today. Aw heck, I’d rather take a plane and get there in just 185 years.

Maps showing the planets and layout of the solar system give a false impression of sizes and distances. But you can hardly blame the creators. There’s just too much empty space between the planets compared to their tiny sizes to squeeze it all a useful diagram. Credit: NASA

Even in the solar system, never mind the stars, distances are so immense we can hardly comprehend them. If we reduced the sun to the size of a grapefruit, Earth would be a poppy seed 35 feet (10.7 m) away, Saturn a pea at 335 feet (102 m) and the nearest star system, Alpha Centauri, a pair of grapefruits 1,800 miles (2,900 km) away. There’s so much emptiness and so little stuff, it’s mind-boggling.

Sunrise and sunset – nature’s most beautiful illusions

Earth turns on its axis to greet the sun at sunrise each morning of the year. Credit: Bob King

Every day the sun rises, crosses the sky and sets. And it does it again and again and again like the perpetually repeating cycle of events in the movie Groundhog Day.

Except perhaps for a few remaining Flat-Earthers, we know what’s going on here. The sun’s not doing the moving. Instead, the Earth’s rotation causes the apparent motion of the sun across the sky. Yet the sense of the sun’s movement is so powerfully ingrained in our experience you might balk if I told you it’s essentially sitting still in the sky.

Every day the turning Earth causes the nearly static sun to rise in the east at sunrise and set in the west at sunset. Credit: Canadian Space Agency

For you to see a sunrise, Earth must rotate on its axis until your location faces the sun as it crests above the planet’s curvature. The following morning, when Earth rolls around after another 24 hours, the sun is very nearly in the same place in the celestial sphere as the previous morning. Once again, we see the sun ‘rise’. Ditto for the next morning and the next. It’s like turning over in your bed each and every morning and seeing your spouse in the same spot. Or very nearly.

If the Earth spun but stood in one spot never circling the sun, we would meet the rising sun at precisely the same time and place every day ad infinitum – a true Groundhog Day scenario. But the Earth orbits or revolves around the sun as surely as it rotates. Just like our daily spin, our planet’s revolution is reflected in the sun, which appears to slowly crawl across the sky, inching its way from one background zodiac constellation to the next, during the course of a year.

The orbiting and titled Earth cause slow but continuous changes in the times of sunrise and sunset during the course of a year. Credit: Thomas G. Andrews, NOAA Paleoclimatology

The ever-changing times of sunrise and sunset stem from the Earth’s orbital travels combined with the shifting seasonal tilt of the planet. From December 21 until June 21, as the amount of daylight increases in the northern hemisphere, the sun appears to travel slowly northward in the sky and we meet its welcome rays a couple minutes earlier each morning.

The sun’s yearly motion across the sky during the year traces out a path called the ecliptic. The top of the curve, at right, is the sun’s position during the summer. The low part of the curve is the sun’s location during winter. The up-and-down path is a reflection of the 23 1/2-degree tilt of the Earth’s axis. Illustration and animation by Dr. John Lucey, Durham University

Then from June 22 to December 20, Earth’s orbital motion causes the north polar axis to slowly point away from the sun. The sun appears to slide south as the hours of daylight wane, and we meet the sunrise a minute or two later each morning.

The sun, located some 26,000 light years from the center of the Milky Way galaxy, takes about 220 million years to make one revolution around its core moving at 483,000 mph. Credit: ESO

Earth moves along its orbit at an average speed of 67,000 mph (108,000 km/hr).

How about the sun? If I left the impression that it’s totally static I apologize. Yesiree, it’s moving too – at the astonishing speed of 483,000 miles per hour (792,000 km/hr) around the center of the galaxy.

Don’t look now, but you and I are going on the ride of our lives.The only reason stars remain static in the sky over the span of many generations despite the sun’s hurry is because nearly all of them are too far away to show a shift in position with the human eye. Telescopes, which magnify everything including motion, do show very subtle changes in the positions of nearby stars over much shorter time intervals.

Rising each morning to the same old sun, I try to remind myself that with every rotation comes a new opportunity to spin some joy into the day.

Summer solstice 2014 – welcome to iced tea, mosquitos and BBQ

The first day of summer begins tomorrow June 21 at 5:51 a.m. CDT. It’s also the longest day of the year. Credit: Lyle Anderson

It’s all about the sun. Always has been, always will be. Our lives depend upon the unstoppable nuclear fire that burns in its heart. At no time of year do we feel closer to that fire than at the summer solstice, when the sun reaches its highest point in the sky in the northern hemisphere.

The difference in altitude between the sun at the summer solstice vs. winter is dramatic. Extra height means both longer days and more intense sunlight – the key reasons summer’s so much hotter than winter. Stellarium

At 5:51 a.m. tomorrow morning June 21 – just after sunrise for my little town – summer begins. If you’ve been paying attention, you’ve noticed the sun creeping higher and higher since the time you last shoveled snow. Well, the buck stops at summer. That’s when the sun stands 23.5 degrees above the imaginary circle in the sky called the celestial equator, an extension of Earth’s equator onto the sky.

If we could remove the atmosphere tomorrow, we’d see the solstice sun high in the constellation of Taurus. The sun’s path across the sky and the celestial equator are shown. Stellarium

For anyone living along the equator, its celestial counterpart starts at the eastern horizon, passes directly overhead and then arcs down to the western horizon. In mid-northern latitudes, the celestial equator crosses the southern sky about halfway between the horizon and zenith. Add in 23.5 degrees or about two fists held at arm’s length against the sky, and that’s where the solstice sun stands around 1 p.m. daylight saving time.

23.5 is a familiar number. You’ll recall that’s the tilt of Earth’s axis. No coincidence there. The sun’s yearly swings from its summer peak at 23.5 degrees above the equator to 23.5 degrees below the equator at the winter solstice is merely a reflection of that tilt. In reality, the sun’s not moving at all – it’s the Earth’s doing.

In northern hemisphere summer (left), the north polar axis tilts in the sun’s direction, causing the sun to appear high in the sky and the days to be long. When it points away, it’s winter and the sun rides low in the sky. At the fall and spring equinoxes, the planet is tilted neither toward nor away and day and night are equal. Credit: Tau Olunga

On the summer solstice, Earth’s north polar axis tilts toward the sun, ‘lifting’ it 23.5 degrees above and beyond the equator. Not only is the sun high in the sky, it’s up for many more hours than during the winter. Days reach their maximum length and the sun’s high angle means the energy per unit area it pours over Earth’s surface is more than twice as intense as during the winter. Add it all up and you’ll start feeling … sweaty.

See the seasons unfold before your eyes. This is an animation using monthly global images from the NASA Earth Observatory taken from January to December 2004.

Enjoy the best the sun can bring to the game these next three months. Happy solstice!

Magnetic collapse makes Saturn’s auroras dance the cha-cha

Images of auroras over Saturn’s north pole in ultraviolet light with the Hubble Space Telescope capture moments when Saturn’s magnetic field is affected by bursts of particles streaming from the Sun. Click to enlarge. Credit: NASA, ESA, Jonathan Nichols (University of Leicester)

Saturn shines brightly in the late May evening sky. You can see it now at nightfall by following an arc starting with fiery Mars and passing through Spica. Continue and you’ll end up at Antares, the alpha luminary in Scorpius. Did you know that it also shimmers with auroras too just like the Earth?

Recent Hubble Space Telescope photos taken in ultraviolet light, where the aurora shines brightly, show bursts of light shooting around Saturn’s polar regions traveling at more than three times faster than the speed of the gas giant’s roughly 10-hour rotation period.

Saturn’s auroras shine brightly in UV but would appear deep red at the bottom and violet at top with the naked eye. That’s because hydrogen gas dominates the planet’s atmosphere and emits light in different colors when bombarded by the energetic electrons in the solar wind. On Earth, excited oxygen and nitrogen molecules produce the more familiar greens, reds and blues of northern lights.

A magnetosphere is that area of space around a planet that’s controlled by the planet’s magnetic field. The shape of the Earth’s magnetosphere is the direct result of being blasted by solar wind, compressed on its sunward side and elongated on the night side forming a magnetotail. Saturn’s is similar. Credit: NASA

University of Leicester researchers recently discovered an amazing connection between Saturn’s and Earth’s auroras. Both planets are surrounded by teardrop-shaped magnetic domains called magnetospheres generated by the churning of materials within their cores. In each case, the side facing the sun is compressed and flattened, while the other side is drawn out into a long tail called a magnetotail.

“Our observations show a burst of auroras that are moving very, very quickly across the polar region of the planet. We can see that the magnetotail is undergoing huge turmoil and reconfiguration, caused by buffering from solar wind,” said Jonathan Nichols, of the University of Leicester’s Department of Physics and Astronomy, who led the Hubble observations.


NASA’s THEMIS Spacecraft See magnetic reconnection / collapse in Earth’s magnetotail

What’s happening – and you can see it clearly in the video above – is that the incoming solar wind connects to and ‘peels back’ a portion of the magnetic field on the dayside of both Earth and Saturn. When the lines pinch together and reconnect on the back or magnetotail-side, a torrent of solar electrons is funneled into the upper atmospheres of both planets. Voila – aurora borealis! Here’s another video showing it from a slightly different perspective.


Dance of Saturn’s auroras

“The particular pattern of auroras that we saw relates to the collapsing of the magnetotail,” Nichols added. “We have always suspected this was what also happens on Saturn. This evidence really strengthens the argument.”

Cool beyond cool. Earth and Saturn are auroral buddies.

Follow the arc from fiery Mars in the south through Spica to find Saturn. Keep going all the way to Antares. All four are magnitude 1 or brighter. The map shows the sky around 10:30 p.m. local time facing south. Stellarium

With a tip of its rings, Saturn greets Earth on opposition day

The north face of the rings are tipped nearly wide open toward Earth this year, making for wonderful views of the planet through a small telescope. Notice that Saturn’s south polar region barely pokes out below the ring plane. This is a fun detail to try and see in a telescope. Credit: Anthony Wesley

Saturday is truly Saturn’s day this year. We mark the ringed planet’s opposition today, the time when it’s closest to Earth and brightest for 2014.

Opposition occurs when Earth passes between Saturn and the sun. When both planets lie on the same side of the sun, they’re almost 175 million miles closer than when they’re on opposite sides. That translates to a bigger, brighter Saturn. Because Saturn travels a little ways around its 29.5 year orbit every year, Earth requires about 13 days to catch up to it at each succeeding opposition. We’ll line up again next year on May 23.

Earth and Saturn are lined up with the sun today and 173 million miles closer than they’ll be in about six months when Saturn is in conjunction with the sun. Illustration: Bob King

The word opposition refers to Saturn being opposite the sun in the sky, rising when the sun sets and setting at sunrise. In a word, it’s visible all night long. Just about anytime you feel like pointing your telescope Saturn’s way, it awaits your gaze.

But before we talk telescope views, let’s take a minute to pinpoint the planet’s location in the evening sky. While it rises at sunset, it doesn’t clear the low trees until about an hour and a half later. Skywatchers at mid-northern latitudes will find it low in the southeastern sky around 10 o’clock well to the lower left of Mars, due south at that hour.

This map shows the sky around 10 p.m. local time tonight May 10 facing south-southeast. Saturn is smack in the middle of the dim constellation Libra below and to the left of Mars and Spica. Stellarium

Tonight the gibbous moon won’t be far from Mars, making it exceptionally easy to find the Red Planet. Swing down to the lower lower left of Mars to spot Saturn. You shouldn’t have trouble spotting it – at magnitude +0.1 it’s nearly as bright as Vega and a pale yellow-white. The ring bearer’s out all spring and summer, so there will be many opportunities to see it.

The ring bearer calls the dim zodiac constellation Libra the Scales home in 2014. Because the moon’s waxing toward full, it’s tricky at the moment to see Libra’s dim stars. Wait till after May 16 for a better view. Maybe then you’ll notice the whimsical “Saturn Cross” like I’ve been seeing the past couple weeks.

A whimsical “Saturn Cross” formed from Libra’s brightest stars with Saturn at its center. Libra precedes the gangly Scorpius the Scorpion with its bright star Antares. Viewing time shown is 1 a.m. in mid-May. Stellarium

The “Cross”, which just happens to be oriented north-south like the constellation Crux a.k.a. ‘Southern Cross’, is simply a different way to see Libra’s four most prominent stars. Saturn marks the center of the crossbeam.

If you’ve never seen the real Southern Cross, this might serve as a cheap, no-airplane-travel-required substitute. Mostly I bring it up as an easy way for you to add a new and rather faint constellation to your life list.

As Saturn travels around the sun in its 29.5 year orbit, we see one side of the rings for about 15 years, followed by an edgewise presentation. The rings – made of dirty water ice – are huge at some 155,000 miles wide (250,000 km), but they’re only about 30 feet thick and virtually disappear when seen edge-on.

That last happened in 2009. Since then they’re re-opened with the north face visible for some 15 years.

Saturn on April 6, 2014. Its clouds belt are less contrasty than Jupiter’s and except for the prominent north equatorial belt not easy to see. A small telescope and magnification as low as 30x will show the rings. Higher power will show the wide B-ring and thinner, outer A-ring. Also visible is the dim C-ring, the dusky band in the foreground crossing in front of the planet. Credit: Efrain Morales Rivera

This year the ring plane’s tipped open 21-22 degrees, nearly the maximum of 27 degrees which occurs in 2017. A large tip exposes lots of ring ice particles to sunlight, boosting the planet’s brightness.

Views of Saturn at different ring plane inclinations taken by the Hubble Space telescope. Rings are labeled in the top image. Credit: NASA/ESA

That’s all good news for both visual and telescopic observation. Even a 2.4-inch telescope will show the rings, with a larger instrument providing a brighter, larger picture and sharper resolution of the three brightest rings. I love the planet’s subtle colors through the eyepiece – the globe looks pale brown or butterscotch to my eye and the rings distinctly brighter and whiter.

Saturn and its brightest moons around 10 p.m. CDT tonight. Titan is brightest at magnitude 9 and very easy to see. North is up. Credit: Meridian software

Small scopes will also show the brightest moons including Titan, Rhea, Dione, Tethys and Iapetus. To find where the moons are on a given night and time, check out Sky and Telescope’s handy Saturn javascript utility, free Meridian software (used to make the diagram above) or download the $2.99 app SaturnMoons.

Saturn’s the best. No other sight in the sky elicits the wonder and amazement of guests at the telescope. Look at the ringed planet every night you can, and the more friends and family your share it with, the better.

Earth rises from the moon … again!

This image, captured Feb. 1, 2014, shows the Earth from the moon-based perspective of NASA’s Lunar Reconnaissance Orbiter. Credit: NASA/Goddard/Arizona State University

Who can get enough earthrises? I mean, look at how beautiful we are. NASA just released a photo and short video of our blue planet lifting off the limb of the moon on Feb. 1 this year. It was taken by the Lunar Reconnaissance Orbiter (LRO) which experiences 12 earthrises every day.

Only thing is, LRO is normally busy imaging the lunar surface; only rarely does the opportunity arise for it to focus its gaze up and beyond the lunar limb. On Feb. 1, the probe pitched forward while approaching the moon’s north pole allowing the wide angle camera to capture Earth rising above the 112-mile-wide (180 km) crater Rozhdestvenskiy crater.

This animation of LROC WAC observations shows the rising Earth from the moon’s limb. Multiple filters were used to make the photo including one for blue light. You can see how much brighter Earth looks because of its blue oceans in the final seconds before it leaves the frame. Credit: NASA/Goddard/Arizona State University

Occasionally LRO points off into space to acquire observations of the lunar exosphere – a atmosphere so rarefied it contains mostly atoms from the solar wind – and perform instrument calibration measurements. During these slews sometimes the Earth (and other planets) pass through the camera’s field of view and dramatic images like this one can be taken. Otherwise it’s ‘nose to the grindstone’ with its eye focused on what’s below.

Unlike an ordinary camera, LRO’s wide angle camera builds up an image frame-by-frame using multiple filters. In the animation the gaps between each frame that create a ‘venetian blind’ effect are from actual gaps between the filters on the camera’s CCD chip. Combined, they form one continuous image.

Another earthrise taken on April 6, 2008 by the video camera aboard the Japanese Kaguya orbiter. Click to enlarge. Credit: JAXA/NHK

The color photo is a composite of six black and white (grayscale) frames of the moon, while the color view of the Earth required three exposures through filters of three different wavelengths that were combined to create a natural color view. This is just how we’d see if we could hitch a ride there.

Notice how much brighter the Earth is compared to the moon. The moon only appears brilliant at night because we see it against a dark sky. Perspectives like these always amaze. They show how fertile and purposeful Earth is in a cosmos that hardly notices.

Forbidding Planet: Scientists find remains of monster asteroid impacts on early Earth

Artist’s view of Earth several billion years ago during the Late Heavy Bombardment, when the planet is thought to have been battered by impacts of comets and asteroids. Credit: Chris Butler/SPL

Earth 3.5 billion years ago was a terrifying place. Picture a rocky landscape pounded by meteorites and asteroids with a surface resembling that of the moon. Volcanoes spewed water vapor but also a toxic mix of carbon dioxide, sulfur dioxide and methane. If you could whisk yourself back to this world by time machine, you’d need to be fully protected by a spacesuit and lucky enough to not get picked off by a falling space rock. Oh, and bring a boat too. Hot-water oceans likely covered a fair portion of the planet back then.


This time-lapse illustration of the Nice (pronounced ‘neece’) model of solar system evolution shows how outer planet migrations kick asteroids into the inner solar system

Scientists call the period from about 3.8 billion to 1.8 billion years ago the Late Heavy Bombardment (LHB), a time when the number of asteroids and their fragments pelting the inner planets and their moons spiked. Why then? No one’s absolutely certain, but the leading theory posits that the migration of the giant outer planets to their present positions “stirred the gravitational pot”, slinging boatloads of asteroids into the inner solar system, where they rained down on Earth and its neighbors in hellish monotony for millions of years.

Anyone with a small telescope can see resulting devastation to this day. Just take a long look at the moon’s battered and cratered surface and thank your lucky stars you’re around during a more peaceful time. Finding Earth’s craters is trickier because water and wind erosion, along with the continual recycling of much of our planet’s crust through plate tectonics, has erased much of our violent past.

The Vredefort Dome – these concentric hills, which rebounded after the impact that created Vredefort Crater – are what remains after an asteroid about 3-6 miles wide struck Earth 2 billion years ago. Credit: NASA

About 180 craters are known on Earth today, but we’re aware of only three resulting from the Late Heavy Bombardment. The oldest, estimated at 3 billion years old and 62 miles (100 km) wide, is also the most recently discovered. Found in western Greenland in 2012, all that remains of the impact are rocks rattled by the massive shock wave that penetrated 15 miles (25 km) deep within Earth’s crust.

You can still see the remains of the impacts that formed the 112-mile-wide (180 km) Vredefort Crater in South Africa, which is 2 billion years old, and the youngest LHB member, the 155-mile (250-km) Sudbury crater in Canada dated at 1.85 billion years.

Map of South Africa with the Barberton greenstone belt shown in red. Shock waves from the impact of an asteroid 3.26 billion years ago created telltale formations within the belt. No one knows yet where the impact happened.

Now, a group of scientists have announced they’ve found evidence for an even older impact, one that occurred 3.26 billion years ago and left its signature in a South African region known as the Barberton greenstone belt.

A recent press release describes the huge impactor as between 23 and 36 miles wide (37- 58 km). Colliding with the planet at 12 miles per second, the jolt delivered was bigger than a 10.8 magnitude earthquake and propelled seismic waves hundreds of miles through the Earth, breaking rocks and setting off other large earthquakes. Tsunamis thousands of feet deep swept across the oceans that covered most of the planet at that time.

A graphical representation of the size of the asteroid thought to have killed the dinosaurs (left), and the crater it created, compared to an asteroid thought to have hit the Earth 3.26 billion years ago and the size of the crater it may have generated. A new study reveals the power and scale of the event some 3.26 billion years ago which scientists think created geological features found in a South African region known as the Barberton greenstone belt. Credit: American Geophysical Union

“We knew it was big, but we didn’t know how big,” Donald Lowe, a geologist at Stanford University and a co-author of the study, said of the asteroid.

The collision would have blasted out a crater some 300 miles (500 km) wide, filled the atmosphere with fiery rock vapor and set the surface of the ocean a-boil. We’re talking serious cataclysm. Somehow life found a way through the heat and crater-punching to gift us with the rolling green hills, coral reefs and forests that characterize Earth today.

Table from the book “Near Earth Objects – Finding Them Before They Find Us” by Donald Yeomans showing average asteroid impact results and probabilities by size. Credit: Donald Yeomans

I try to imagine the dark days of the LHB to help me appreciate these calmer times. Yet we know in our gut – and in fact, thanks to probability – that we’ll never truly be out of the woods. Asteroids lurk in the deep that could one day cause a similar scenario. Don’t let it worry you too much – the chance of a 10-mile-wide space rock striking Earth is once every 89 million years. You’ve still got time to take a nap, catch a show and enjoy a few nights out on the town. Probably.