The video is not too hard to follow. But it runs about 15 minutes. So if you’re busy, just dip into it a bit at a time. By the end, you’ll have a good idea about how studying how spectroscopy may reveal insights into the chemical composition of stars, planets, and perhaps, indirectly, extraterrestrial civilizations.

Thanks to subscriber Suzane for pointing out this and many other astro-related videos. You can see links to more videos here…

March is a “change over” month for the night sky.  The bright stars of the northern winter move westward and give way to the star-sparse nights of March, April, and May.  That’s because we’re starting to look out of the plane of the Milky Way and into intergalactic space.  So we see fewer stars and nebulae and open star clusters, but more galaxies become visible, especially those of the Virgo cluster and smaller collections like the M81 and Leo groups.

And of course, the seasons change this month.  The southern hemisphere begins fall and the northern hemisphere begins spring on March 20 at 17:32 UT.  At this time, the sun sits at the point where the celestial equator and ecliptic meet.  All points on the Earth receive an equal amount of sunlight, hence the term “equinox”, or “equal nights”.

*** Highly Recommended ***

Discover how to take great astro-photos with your digital camera.  Capture images of Orion rising over the trees above the eastern horizon, or Taurus and the Pleiades high in the dark winter sky.  No special experience required.  Click here to learn more…

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For deep sky sights, try the two Messier objects in Cancer, M44 and M67.  Both are old open clusters.  The better-known M44 is more spread out and brighter, but M67 is fun to examine because its shape conjures many analogies.  Some say M67 looks like a fountain of stars.  Others suggest a “Pac-man” shape.  What can you see?

Open clusters M44 (the “Praesepe”), center-right, and M67, lower right.  Also, the spiral galaxy NGC 2903 (center)

And if you’re keen to see a nice galaxy, check out NGC 2903, just off the nose of Leo.  This lovely 9th magnitude spiral is one of the best in this part of the sky.  It was just missed by Messier; William Herschel discovered this galaxy in 1784.  It lies 21 million light years away.  Here’s what it looks like in a big telescope…

As for planets, Mars lingers in western Cancer, not far from M44 and M67.  It’s fading this month, but a good telescope, high magnification, and steady sky will reveal a few surface features.

And Saturn is set to take center stage for planet lovers.  The planet reaches opposition on March 21 and will reach its brightest over the next few months.  More on Saturn below…

Moon

Last Quarter: March 7, 15:42 UT
New Moon: March 15, 22:01 UT
First Quarter: March 23, 11:00 UT
Full Moon: March 30, 2:25 UT

Planets

Mercury lies a generous 10 degrees above the western horizon after just after sunset.  It reaches magnitude -0.9 by month’s end and sits just below the brighter Venus.

Venus is still close to the sun in the western sky, but it rises higher this month to get 10-12 degrees above the horizon by March 31.  It’s not much to see through a telescope since it’s near full phase.  But it makes a lovely pairing with Mercury later this month, and with the Moon on March 16-17.

Mars lingers in the sky, as mentioned above.  At its closest in January, the disk of Mars was 14 arc-seconds across.  It will shrink to 9 arc-seconds by month’s end.

Jupiter is lost in the glare of the sun this month.

Saturn gears up for a good show over the spring and early summer.  The ringed planet hovers in Virgo between the stars Spica and Denebola.  The planet is directly opposite the sun on March 21, and rises high enough for viewing by mid-evening.  The rings are still just 4 degrees from edge-on.  A small telescope at 75x or more will clearly show the rings.  Saturn this month is about 1.27 billion km away from Earth.

Saturn lies in Virgo, between Spica and Denebola.

Uranus is too close to the sun to be observed this month.

Neptune. Just above the horizon at dawn.  Wait for a month or two to try to spot this icy giant planet.

Celestial Events

The March equinox occurs at 17:32 UT, bringing spring and autumn to the northern and southern hemispheres.

And don’t forget to check out the zodiacal light early this month.  Look for a tall pyramid of whitish-yellow light just after sunset.  Dark sky is required.

There are many legends of how Lepus came to be among the stars.

The Roman writer Hyginus wrote of a man who brought hares to the island of Leros to raise them for food.  A few escaped, and before long the island was overrun with voracious rabbits who consumed crops and caused a famine among the human population.  The hares were eventually driven out, but the inhabitants placed Lepus among the stars as a reminder of their experience.

The poor celestial hare forever runs from the Big Dog, Canis Major.  Perhaps that’s why he’s cowering in the hopes of a little protection at the feet of the great hunter.

*** Highly Recommended ***

Discover how to take great astro-photos with your digital camera.  Capture images of Orion rising over the trees above the eastern horizon, or Taurus and the Pleiades high in the dark winter sky.  No special experience required.  Click here to learn more…

* * * * *

Lepus’ two brightest stars lead the way to the constellation’s only Messier object.  Find alpha Leporis (Arneb) and beta Leporis (Nihal), and extend a line south as long as the separation between the two stars.  There you’ll find the globular cluster Messier 79 right next to the 5th magnitude star HIP 25045.

The constellation Lepus, just south of Orion.  M79 is at the bottom of this image; R Leporis is marked by the circular cross-hairs at the middle-right.

M79 shines at magnitude 8.5, so it’s viewable in binoculars in dark sky and easily seen in a small telescope.  It’s fairly compact… just 1/10 degree across, and difficult to resolve near the center, even in an 8-10″ scope.  Some astronomers believe M79 comes from a nearby dwarf galaxy that’s interacting with the Milky Way.  The cluster lies at a distance of 43,000 light years.

But the jewel of Lepus is the deep-red variable star R Leporis, also called Hind’s Crimson star.  Like the star La Superba, R Lep is in the late stages of its life and has begun to churn up carbon from its core.  Once in the star’s atmosphere, the carbon blocks all but red and infrared wavelengths, which gives the star is crimson hue.  It looks like a drop of blood hanging from a vampire’s fang.

Hind’s Crimson Star (R Leporis)

Like many carbon stars, R Leporis is a variable star, changing from magnitude 7.3 to magnitude 9.8 every 420 days.  The fainter is gets, the redder it looks.  This is not a naked-eye object; use your optics to find this lovely star about 3 degrees west of mu Leporis.

*** Highly Recommended ***

Discover how to take great astro-photos with your digital camera.  Capture images of Orion rising over the trees above the eastern horizon, or Taurus and the Pleiades high in the dark winter sky.  No special experience required.  Click here to learn more…

* * * * *

Lowell came from an old, wealthy Boston family that first settled the Cape Ann peninsula of Massachusetts in 1639.  His brother Abbot was president of Harvard University for 24 years.  And Percival himself was a Harvard grad, majoring in mathematics.  He developed an interest in astronomy as a student and delivered a graduation address on the “nebular hypothesis” of solar system formation.

But that was it for astronomy for young Percy… or so it seemed.  After Harvard, Lowell tended to the family business and traveled occasionally to Korea and Japan for 17 years.  He served as a counselor for a Korean diplomatic mission to the U.S.  and wrote four academic books about Japan and its culture, including “The Soul of the Far East” in 1888.

Then, without apparent reason, he caught the Mars bug.  Inspired by the writings of Camille Flammarion and the observations by Schiaparelli of Martian canali (which translates from Italian as channels, not canals), Lowell became convinced Mars was inhabited by an intelligent civilization.

In 1894, Lowell used his fortune to quickly build an observatory near Flagstaff in the clear, dry Arizona sky.  He set up two borrowed refracting telescopes and set to work sketching the surface features of Mars, and he continued sketching and making measurements of Mars for more than 15 years.  His observatory eventually housed an impressive 24-inch refractor made by Alvan Clark.  The telescope remains in use at Lowell observatory to this day.

Not long after his first observations in 1894, Lowell loudly announced his discovery of canals and oases on Mars, which he believed were created by the inhabitants of the Red Planet.  The public was captivated.  Lowell became world famous.  And the idea of life on Mars remained in the public consciousness for decades.

One of Lowell’s sketches of Mars, circa 1895

Professional astronomers had a different reaction to Lowell.  Many were disgusted at Lowell’s thirst for publicity.  Some believed he jumped the gun to announce life on Mars without more careful study and analysis.  No other astronomers could see canals on Mars, including the eagle-eyed E. E. Barnard with the 36-inch telescope at Lick Observatory.

Many began to believe (correctly) that the canals were an optical illusion.  Skepticism about the canals increased amongst astronomers over the 20th century.  Though it was not until Mariner 4’s flyby was the existence of canals was disproved completely.

If Lowell was troubled by the scorn and derision of the astronomical establishment, he didn’t let it show.  He remained at his telescope for the rest of his life, making drawings of Mars, as well patiently sketching an early map of Venus.  Though again, what he saw on Venus was uncertain since we know now Venus reveals no surface features in visible light.

Lowell also predicted a ninth planet– which he called Planet X– based on oddities in the orbits of Uranus and Neptune.  He searched for Planet X himself until his death in 1916.  The observatory’s staff continued the search until 1930, when Clyde Tombaugh discovered Pluto at Lowell Observatory.  Though it turns out Pluto was too small to be Planet X, and the whole issue disappeared when, much later, accurate determination of the mass of Neptune showed the outer planets moved as expected.

So Lowell was wrong on Mars.  He was wrong on Venus.  He was wrong on Planet X.

Was he a failure?

We think not.  Though he made few original scientific discoveries, Lowell left a legacy of a world-class observatory which still contributes to the advancement of human knowledge.  And he stimulated public imagination for planetary exploration more than anyone in his time.

We wonder how many astronomers of the past century owe their careers to Lowell’s imagination and dedication.

Today, Lowell’s Observatory is a U.S. National Historic Landmark.  His mausoleum stands on Mars Hill near the observatory.

This short video from the Discovery Channel presents five reasons that life may exist on Mars. The last reason… the discovery of a seasonal source of methane… is especially fascinating.

Something to think about as you turn your telescope skyward to get a look at the planet while it’s still high and bright.

In the 17th and 18th centuries, early telescopic astronomers glimpsed polar caps– much like Earth’s– that grew and shrank with the Martian seasons.  The Martian day turned out to be about the same length as Earth’s.  The axial tilt was similar to Earth, too, which meant Mars has seasons much as we do.  And those strange dark surface markings… were they water?  Or vegetation?

Then in the mid-1800’s, the Italian astronomer Giovanni Schiaparelli claimed to see long, thin lines on the surface of Mars.  He called them canals, and he mapped them meticulously.

American astronomer Percival Lowell saw the canals too and loudly claimed they were irrigation structures built by an advanced Martian civilization.  Inspired by Lowell’s claim, H.G. Wells wrote “War of the Worlds”, which has been re-purposed into radio events and movies over the decades.  The possibility of “Men from Mars” stoked the imagination of science fiction writers and readers through the first half of the 20th century.

But as telescopes improved, few other astronomers could see the canals which were– correctly– dismissed as an optical illusion.  Some denounced Lowell as a crank.  And the existence of life on Mars remained tantalizing, but unproven.

Then, in 1965, space probes were dispatched to Mars to get a better view.

Image from Mariner 4.  Lifeless Mars?

In 1965, the Mariner 4 space probe flew past Mars and snapped 22 black-and-white images of a tiny part of the Martian surface.  The images showed craters– big ones– which suggested Mars was more like our moon than the Earth.  So no Martian forests, or canals, or cities.  The New York Times wrote a feature article declaring Mars “a dead world”.  Later, Mariners 6 and 7 showed more craters, and many planetary scientists gave up hope of finding life on Mars.

But one scientist thought this conclusion was premature.  Carl Sagan, along with a few colleagues, suggested the coverage and resolution of the early Mariner images were too poor to confirm the absence of life.

Then NASA sent Mariner 9.

In 1971, this probe became the first to orbit Mars.  At first, the images showed only the white polar caps and a featureless surface.  That’s because the probe arrived during a planet-wide dust storm which lasted weeks.  As the dust cleared, the images revealed a startling display of surface features including immense volcanoes, canyons, and river beds that suggested the one-time presence of liquid water.  The atmospheric pressure on Mars is too low to sustain liquid water now.  But where did the water go?  Underground?  Frozen in the polar caps?  If so, maybe there was still hope to find life elsewhere on the planet.  The chase for life on Mars was on again.

Carl Sagan with a mock-up of a Viking Lander

Five years later, NASA landed the two Viking probes on the surface of Mars.  They sent back thousands of pictures of a dry, rusty, rocky surface.  And they grabbed samples of the Martian soil and conducted on-site chemistry experiments to look for the telltale signs of life.

The results?

At first, they looked promising.  But after a little thought, most scientists concluded there was no definitive evidence for life on the surface of Mars.

Sadly, other surface probes since Viking, right up to the current Phoenix Lander, have found no evidence for life.  No palm trees or hubcaps, no bacteria or organic molecules.  More missions are planned in the coming years, including the European ExoMars mission which will dig two meters into the surface to look for signatures of life.

One more strange thing…

In 1984, a meteorite was found in Antarctica.  Scientists were certain the meteorite came from Mars.  It was likely knocked of by a volcanic eruption or asteroid impact, and its chemical composition was the same as the surface of Mars.  In 1996, a group of scientists suggested they found fossilized evidence of bacteria in this Martian meteorite.  But these results have been in dispute on and off ever since; no strong conclusions one way or the other have been declared.  Though late last year, the same scientists concluded once again that this meteorite contains evidence of life on Mars.

So no one’s found clear-cut evidence of life on Mars, but we’ve only examined a tiny part of the surface.  Upcoming missions may yet lead to the most startling scientific conclusion ever made… that life exists somewhere other than Earth.

Stay tuned…

And check out this image of “life” on Mars… it’s obviously a rock formation that just happens to take on a human form.  Isn’t it??

Spirit is no longer roving, but is still transmitting data as a stationary platform.

Opportunity just arrived at Concepcion crater, after visiting Erebus and Victoria craters during its long and eventful mission.

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Here’s the video:

How’d you like to go on this ride?

For more details on this impressive NASA mission to Mars, check out the mission homepage right here.

And remember… Mars remains well-placed for viewing this week.  It’s shining red and bright in the constellation Cancer, and offers a number of surface details for inspection by sharp-eyed observers with a telescope.

In an odd way, the presence of Mars’s moons was predicted more than two centuries before they were discovered in 1877.

Johannes Kepler, always a believer in mathematics and symmetry, reasoned in the early 1600’s that if Earth had one moon and Jupiter had four moons, then Mars must have two moons. While Kepler was a good mathematician, his mystical beliefs led to some strange reasoning.

But it gets stranger.

In 1726, Jonathan Swift wrote of Mars’s moons in Gulliver’s travels and assigned orbital diameters and periods not far off the true values, though he presumably had absolutely no way of knowing these quantities. Voltaire also mentioned these moons a few years later in his story Micromegas, though he may have got the idea from Swift.

But the true discovery of the moons awaited the construction of the great 26-inch Clark refractor for the U.S. Naval Observatory in Washington. There, the sharped-eyed astronomer Asaph Hall spotted the moons in August 1877. (Hall had made other remarkable sightings at the observatory, including a visit by President Abraham Lincoln, who showed up alone one night to talk astronomy). Soon after their discovery, the moons were named after the sons of Ares, the Greek god of war. Phobos represented fear, and Deimos, dread.

Unlike our own moon, which formed at the same time and likely within the same gravitational well as Earth, Phobos and Deimos are likely just small captured asteroids. Phobos measures 22.2 km across and orbits Mars every 7.7 hours. Deimos is even smaller — just 12.6 km across– and orbits Mars every 30 hours. They’re a speedy sight in the Martian sky. Phobos, especially, moves quickly, rising and setting every 11 hours. The image at the top of the page shows how the moons looked to the Spirit Rover in 2005.

Here’s what the moons look like a little closer up:

Deimos (left), and Phobos, the moons of Mars

Over time, Deimos will experience tidal forces that will cause it to lose energy and move to a more distant orbit.

But Phobos will experience a different fate.

Tidal forces will cause Phobos to move closer to Mars until it undergoes a gravitational shearing force that rips it to pieces. The remains of the moon will scatter along the equatorial region of Mars. Other small Martian moons may have already experienced this fate: there are trails of craters strewn along the Martian surface that may have been caused by captured asteroids crumbling and spiraling into the planet.

This idea’s been around for a long time, no doubt.  But I first thought of it when hearing about tourists and artists observing Michaelangelo’s paintings on the ceiling of the Sistine Chapel.  Instead of craning their necks for hours, the art lovers looked at a reflection of the ceiling from mirrors held at waist level.  It’s far more comfortable, and even an inexpensive mirror does a fine job giving a true image of priceless art.

The same idea works for stars.  If you want to spare your neck, get a small mirror (say at least 12 inches square), hold it face-up towards the sky, and let the star light reflect into your eyes while holding your neck at a comfortable angle. Or if you really like comfort, hold the mirror on your lap as you sit in a comfortable chair.  It’s a little strange at first, since the image you see is flipped left-to-right, but you’ll get the hang of it after a little practice.  It sounds obvious, but you won’t find many people trying this at a star party.

Some have adapted this idea for binoculars.  Here’s a home-made version of a mirror-binocular combination…

A binocular mount with a mirror to capture the sky in reflection.  Great for preventing neck strain.  Here’s a link to help you build your own.

I’ve used a commercial version of this mount a couple of times, and it works well.  Even a low-cost mirror doesn’t seem to impart much distortion to the image from binoculars.  If your neck pain gets in the way of stargazing, try out a mirror… you’ll enjoy the sky more if you do.

]]> http://www.oneminuteastronomer.com/2010/02/04/window-sky/feed/ 0 http://www.oneminuteastronomer.com/2010/02/01/sky-month-february-2010/ http://www.oneminuteastronomer.com/2010/02/01/sky-month-february-2010/#comments Mon, 01 Feb 2010 18:06:45 +0000 admin http://www.oneminuteastronomer.com/?p=1164 Overview

An anniversary this month: 80 years ago, the young astronomer Clyde Tombaugh discovered the (former) planet Pluto at Lowell Observatory after a year of grinding, diligent work.

Through most of 1929 and early 1930, Tombaugh photographed and analyzed hundreds of star fields along the ecliptic from Cancer to Gemini in search of “Planet X”.  Tombaugh planned to start his search in Gemini, but the full moon was in the way.  So he started just next door, in the constellation Cancer, and worked his way all the way around the sky back to Gemini a year later.

Turns out Pluto was in Gemini after all.  It seems Murphy’s Law applies to the heavens as well.

Now for this month’s sky.  If you liked January, then you’ll like February even more…

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The bright stars of Orion, Taurus, and the Big and Little Dogs still dominate in the north; the summer Milky Way arcs across the sky south of the equator, offering hundreds of deep-sky objects for inspection with binoculars or a small scope.   Mars still shines bright and beckons the patient observer to look for dark markings of crater fields and white polar caps against the orange-red desert that dominates the planet.

And Venus returns this month.  The bright planet slowly emerges from the sun’s glare to make an appearance in the early evening sky.  In mid-month, Venus meets with Jupiter and the crescent moon just after sunset to put on a beautiful show.

February also presents an uncommon chance to spot the bright asteroid Vesta.  At opposition on February 17, Vesta cruises through the constellation Leo over the next several weeks.  As we explain below, the best nights to spot this 6th magnitude asteroid are February 16-17 when it passes between the bright stars gamma Leonis and 40 Leonis.

Looking for a short and sweet observing session on a busy February night?  Northern observers can look almost directly overhead for the star clusters of Auriga, especially M36, M37, and M38.  And don’t forget ε Aurigae, the strange  stellar system that’s now in the midst of an eclipsed as a flat, dark disk of material passes in front of the star.  The star is expected to dim again over the next several months.  Just 2 degrees west of epsilon, look for the sparse but unmistakable open cluster NGC 1664.  A small scope at low-to-moderate power gives the best view.

Star clusters in the constellation Auriga.  Check out M36, M37, and M38, along with NGC 1664 and ε Aurigae (right)

In the southern hemisphere, you’re spoiled for choice.  For a quick look, take a look at the triple star alpha Crucis at the foot of the Southern Cross.  The close pair of whitish stars is separated by 4″; you’ll need a telescope at 50-80x or more to split them.  The fainter 3rd star lies some 90″ away.  And check out more colorful pair alpha Circini just southeast of Crux and next to alpha Centauri.  The yellow and red components of this double are a fine sight in a 3-inch or larger scope.

Moon

Third Quarter: Feb. 5 at 23:48 UT
New Moon: Feb. 14 at 2:51 UT
First Quarter: Feb. 22 at 00:42 UT
Full Moon: Feb. 28 at 16:38 UT

Planets

Mercury. Still visible about 7 degrees above the eastern horizon at sunrise.  Binoculars give you a better view.  The planet moves back towards the sun and brightens over the month.  Best view is from the southern hemisphere.

Venus moves a little higher above the western horizon each night.  It’s too close to the sun early this month to see with the unaided eye.  But by mid-month, it begins to move higher than the fast-sinking Jupiter.  As the planets pass, they make a striking pair beside the thin crescent moon.  Scan the skies just after sunset on Feb. 14-16 for the best view.  Binoculars will help.

Mars. Though it will fade somewhat over the month, Mars is still a dominant presence in the eastern sky in the constellation Cancer.  The faster-moving Earth is now passing by Mars, which causes the planet to appear to move westward in the sky rather than the normal eastward direction.  This “retrograde” motion comes to an end on March 11.  For the best chance at seeing surface features, observe the planet with a telescope when it’s high in the sky.  Mars lies just 3 degrees north of M44 in Cancer on Feb. 4

Jupiter. The King of Planets has dominated the sky for the past 8 months, but it’s sinking into the western sky at sunset.  Though it’s by no means primed for telescopic viewing, the planet makes lovely conjunctions with the crescent moon and Venus in mid month.

Saturn rises earlier each night… about 8:30 p.m. local time by mid month.  It’s finally high enough to see at a decent hour, certainly before midnight if you have a clear view of eastern Virgo.  The rings are close to edge-on; the disk is a respectable 19″ across… larger than Mars.

Uranus sinks low in the sky at sunset; Neptune is lost in the sun’s glare.

Celestial Events

• There are no major meteor showers this month, and no comets within reach of small scopes.  But there are some events worth checking out…

• The Zodiacal light is most evident from Feb. 1-15.  Look for this eerie glow about an 90 minutes after sunset.  It looks like a white pyramid of light extending along the zodiac.  Dark sky is required to see this.

• On Feb. 24, the bright star Wasat in Gemini is occulted by a gibbous Moon.

• And the bright asteroid Vesta puts on a show in Leo.  Vesta shines at magnitude 6, so it’s not easily visible with the unaided eye.  A pair of binoculars or a small scope will show it clearly.  Feb. 16-17 offer you the best chance to easily find this minor planet, as Vesta passes through the tiny space between the bright stars Algieba (gamma Leonis) and 40 Leonis just below.  You may see the asteroid move with respect to these stars over the course of a few hours.  Well worth a look.  Use the map below to track Vesta across the sky.

A map showing the path of the asteroid Vesta across the constellation Leo in early 2010 (from Sky and Telescope).

Vesta was the 4th asteroid discovered.  Olbers first spotted it in 1807.  It’s about 500 km across, which ties it with Pallas for second place behind the largest asteroid, Ceres.