Tag Archives: astronomy

April Skywatch

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I’ve promised a column on some telescope basics, and as the evenings start to warm up it’s finally time to deliver. Maybe you’re interested in more stargazing than casual naked-eye observations from your back porch, but you’re unsure of where to begin. Sometimes the options for purchasing a good starter telescope seem quite daunting. Where to begin? What type should I get? Which mounting is best? How do I avoid a cheap dud?

This month, I’ll offer a few pointers on choosing and getting started using a telescope for some basic backyard observations. As I’ve mentioned before, I focus on observing objects that you don’t need to be in perfectly dark skies to see. My own stargazing takes place in the city limits of Kankakee, with streetlights, trees, and the occasional porchlight marring the view. With a little knowledge and patience though, even a city sky can be a treasure trove.

Of course, it all starts with a good telescope. When I was preparing to purchase a new set of telescopes for my astronomy labs at Olivet several years ago, I asked the members of the Kankakee Area Stargazers for advice. I wanted instruments that were high quality but relatively inexpensive, easy to use and train students to use, and resilient enough that I wouldn’t worry about them being easily damaged The scope most recommended was a basic 6-inch Dobsonian reflector from Orion Telescopes. I purchased a small fleet of these instruments for student use and have had no regrets. They are simple, durable, and offer great viewing.

So what exactly is a 6-inch Dobsonian reflecting telescope? We’ll start with “reflecting.” Telescopes come in two basic types: reflectors, which use mirrors to gather light, and refractors, which use lenses. If you walked into Wal-Mart for a cheap telescope, you’d almost certainly be buying a refractor. Though there certainly are many refractors that are very high quality, you’re not going to get one like that at Wal-Mart. For a real quality refracting telescope, you would be spending several times more than you would for a reflecting telescope of similar size. If you’re looking for a serious but affordable starting instrument, stay away from refractors and start with a good reflector.

The next question is regarding aperture or (in simple terms) size. Generally speaking, the larger the diameter of a telescope, the better view you’ll have of objects. But also generally speaking, larger aperture also means larger price. Six inches offers enough light-gathering power to easily showcase Saturn’s rings or the moons Jupiter, hone in on the Moon’s craters, or (in dark skies) reveal distant nebulae and galaxies.

Next, you need to consider how the telescope is mounted. As it turns out, pointing and holding the telescope steady is one of the most important parts of getting good views (and not getting incredibly frustrated). There are lots of different ways to mount a telescope, but the type known as a Dobsonian mounting is the sturdiest and easiest that I’ve worked with. A Dobsonian mount makes it very easy to point the telescope to an object in the sky (especially if you spring for a simple laser-finder) and to keep the object in sight and steady once found. And if you’re observing with students or young kids, having a telescope that is on a steady and solid mounting is crucial.

Once you have your telescope picked out, the second step is to get a handful of eyepieces to use with it. Eyepieces magnify the image of the telescope, with the general rule that for a specific instrument smaller eyepiece focal length yields higher magnification. If you’re looking at large objects like the Moon or star clusters, you’ll want to use an eyepiece with a longer focal length (e.g., 25 mm). Then, when you want to zoom in on lunar features or try to split very tight double stars, you use an eyepiece with a shorter focal length to magnify the view. Most telescopes come with two or three eyepieces, and this is usually plenty for the beginner.

Finally, you need to know how to find the objects in the sky you want to view. I tend to eschew computerized mounts that point the telescope for you or tell you where to point it, because I think part of the fun is becoming familiar with the night sky yourself. But you’ll need some good resources to get you started. A quality star atlas is a must (I use the Cambridge Double Star Atlas), but it’s not much to go on if you’re just beginning. I’ve found James Mullaney’s Celestial Harvest to be an excellent guide to highlights in each constellation, and a tool like Guy Ottewell’s Astronomical Calendar (which unfortunately won’t be published after this year) lets you know what planets and constellations to spot when.

Then comes patience. Wait for clear nights and determine what constellations will be overhead. Do a bit of reading before you head out (or take a red flashlight with you to read at the telescope) and simply try to become familiar with the objects in one or two constellations at a time. Don’t feel like you need to learn the entire sky immediately. This month, for instance, Leo is a great place to start, from the lovely double star Algieba in the Sickle of Leo’s mane, to Jupiter and its moons just below the constellation (always a wonderful sight to start with), to the sweep of galaxies beyond Leo’s tail (though you’ll need to get away from the city lights to really appreciate these).

You’ll be amazed at what passes over your head each evening, generally unappreciated and unobserved, but within reach with a simple, good instrument.

This column first appeared in the Kankakee Daily Journal.

Against Infinity

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Against InfinityAgainst Infinity by Gregory Benford

My rating: 4 of 5 stars

I picked up Gregory Benford’s Against Infinity at a used book store a while ago and then put it away to save for portable airport reading on my recent trip to Italy. (Pocket editions like this are truly the best books to travel with.) The book was an effective escape, staving off my growing impatience with multiple delays out of Chicago’s O’Hare because of high winds in New York City.

Against Infinity had more heft to it than I expected, and more beauty as well. Benford had been on my list for a while as a practicing astronomer who wrote science fiction, and I hadn’t been disappointed with his Great Sky River. This one was an interesting fusion between an Arctic survivalist story and the wonder and ecological trappings of Dune. On top of this, it offers a scientifically realistic view of what Ganymede and the Jovian system might look like as a legitimate frontier for settlement. The characters are scouring a living on the surface of the moon, clawing for minerals and slowly tipping the biosphere toward something that can sustain life.

Overlain on this is a hunting tale in the tradition of Jack London and the Yukon, complete with super-intelligent biomechanical dogs and a meaningful coming-of-age narrative. A boy is growing up, forging a bond with an older, wiser hunter, coming to terms with his father, and learning his own limits. The object of the hunt that provides the context for this growth is men venturing out of their settlements into the icy, shifting landscape to cull the mutants of the genetically engineered species that have been introduced to help terraform the surface. The actual object of the hunt though—and ultimately the lynchpin of Benford’s narrative—is the Aleph.

The Aleph is an ancient device or creature that pre-dates man’s arrival on Ganymede and continually burrows through or over the surface of the moon, heedless to its pursuit by men, unaffected by any of their weapons or devices, and sometimes killing them in its passage. The concept, especially in the haunting descriptions provided by Benford, is a compelling hybrid of the raw power and immensity of the sandworms of Arrakis and the alien inscrutability of the monoliths of Arthur C. Clarke’s Space Odyssey. Benford’s prose becomes positively electric in describing the various ways this enigmatic thing chews through the shattering and slowly thawing terrain of the moon. He can (and does) spend multiple pages on all the glorious details of the behemoth exploding through a hillside, for instance, taking its pursuers unaware.

The first two-thirds of the book hinges on one boy’s growth to manhood and fixation on hunting the immense and elusive Aleph. It reads very much like a science fiction tribute to Jack London: the boy learning the ways of the hunt, training a tracking dog (of sorts), and learning to appreciate the unique bond between man, animal, and the unforgiving wilderness. But whereas a reader of London can take the ecology of Alaska for granted, Benford the astrophysicist gives us a fine-grained detail of the geology and young ecosystem of the moon, a realistic look at what terraforming and its effectives might look like physically as well as psychologically.

But the true hinge of narrative is the Aleph, and the resolution of its pursuit changes the trajectory of the novel about two-thirds of the way into it. After this climax is reached, the narrative jumps in time and expands in scope. The Aleph moves from being a cypher for the great unknown on a boy’s horizon to a much larger unknown of the evolution of humanity. Like the dissected Aleph itself though, this final portion of the novel seems more segmented and less organic than what came before. Benford touches briefly (and a bit randomly) on ideas regarding the evolution of society, including socialism and capitalism essentialized against ecological catastrophe. In this all, the Aleph’s role (and ultimate nature) becomes more vague and less satisfying.

March Skywatch

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I’ve been promising a column for a couple months now that offers a basic introduction to telescope optics and usage. I plan to keep that promise, but exciting news keeps breaking out in the astronomical world. Last month it was the alignment of the planets in the early morning skies and the announcement of the possible existence of a new, ninth planet in the solar system. Now it’s even bigger news, as scientists have reported the first confirmed detection of gravity waves, which not only provide a further confirmation of Einstein’s theory of general relatively but more importantly have opened a completely new avenue for learning about the universe.

Up to this point in our history, everything we’ve known about distant objects in space has come from light, whether telescopes set up in backyards or research observatories on mountaintops or even instruments beyond the surface of the Earth like the Hubble Space Telescope. All of these gather types of light (which includes all portions of the electromagnetic spectrum, from the visible light we see up to high-energy gamma rays and down to low-energy radio waves). Light can tell us a lot about the universe, from the velocity of galaxies to the chemical make-up and temperatures of stars. Until now, all discovery related to the distant universe has been through studying light.

But a century ago Einstein predicted that there may be another means of learning about the universe. According to his theory of general relativity, massive moving objects should give off gravity waves, distortions in space that spread outward at the speed of light like ripples on a pond. These waves would be a completely new way of giving us information about objects in space. It would be as though having only before seen distant objects in space, now we would be able to “hear” them as well.

The problem was that gravity waves would be incredibly, almost unimaginably weak and thus very, very hard to detect. As a gravity wave moves through space, it contracts space slightly along one direction while stretching it in a perpendicular direction. This contraction and stretching is tiny, amounting to something like a thousandth of the thickness of a single proton. To detect such miniscule variations in length, scientists have had to build some of the most sensitive detectors ever.

How do you detect the warping of space caused by gravitational waves? There are several detectors around the world, but the two in the U.S. that detected this first confirmed signal (which passed through the planet—and all of us—last September) were the twin detectors of LIGO, the Laser Interferometer Gravity wave Observatory, located in Washington state and Louisiana. LIGO reflects a beam of light down two 2.5-mile tunnels at right angles to each other and by analyzing the beams can detect a tiny difference in the lengths of the tunnels caused by gravitational waves. This past September they both received a signal, and after months of analysis scientists were confident that it was indeed a gravity wave.

Aerial5
Aerial view of the LIGO Hanford Observatory, courtesy LIGO Image Gallery, http://www.ligo.org/multimedia/gallery/lho.php.

This particular signal appears to have come from two black holes billions of light years away in the process of colliding and merging to form one larger black hole. Scientists are able to predict how such an event would “sound” (that is, what sort of gravity waves it would give off), and the signal detected matches this prediction. Scientists are also able to triangulate using the detection at the two different sights to get an idea of where in the sky the signal came from, though it’s far too distant to observe with visible light.

But that’s exactly the point: with this confirmation, we now have a completely new way of observing the universe. We’re in a similar situation to when Galileo first turned a telescope—at the time a completely new scientific instrument—to the heavens. We have a new tool, and we’re not sure what we’ll discover.

Yet our very first observation has already shown us something exciting: double black holes that eventually collide have long been predicted but never before observed. It turns out the very first thing we’ve “heard” with our new ears on the universe is itself something new.

This column first appeared in the Kankakee Daily Journal.

February Skywatch

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5-planets

It’s been an exciting month for skywatchers! Last month I talked about some of the easy sights for backyard telescopes in the constellation Orion, which is looming large in our evening skies. The first couple weeks of February though, offer an even more impressive naked-eye sight in our morning sky: the possibility of glimpsing all five visible planets arranged in a straight line across much of the sky. The arrangement is best right now and will continue throughout the first week of February.

Standing outside before dawn, look to the east. Venus is bright above the eastern horizon, and if you have a clear view you may catch elusive Mercury even lower toward the Sun’s glow. Saturn is above Venus to the south, with Mars riding high in the southern sky. Jupiter is the bright object beyond Mars, toward the southwest. Altogether, the planets make a lovely arrangement that spreads across nearly the entire southern skies. The best time to look for them is just before sunrise, around 5:30 to 6:30, at which time the Sun’s glare begins to wash them out.

The mornings of this first week also bring an additional sight to the arrangement: a lovely slender crescent moon which passes by Mars on February 1st, is near Saturn by the morning of the 3rd, and moves down toward Venus on the 5th. An arrangement like this, with all the planets neatly in a row along the ecliptic, is fairly rare, so make an effort to rise early and take a look at this vista of the closest worlds of our solar system.

I mentioned last month I’d spend this column talking about telescope basics, but planetary happenings are enough to push that back a bit. Besides the arrangement of visible planets, astronomers grew quite excited this week with news of new evidence that might indicate the existence of an undiscovered ninth planet in our solar system.

When you look up at the pre-dawn sky this week, you can see all the visible planets in our solar system, which are all the planets that were known throughout most of history. It was only in the late 1700s that we began to realize there were other planets in our own backyard, and this most recent announcement may herald that our family of planets is about to expand again, for the first time in over a century.

All of this obviously makes astronomers pretty excited but also cautious, as there have been lots of false claims for Planet X in the past.

Until William Herschel stumbled upon Uranus in his telescope sights in 1781 and subsequent calculations showed that it wasn’t something like a comet, Saturn was considered the outer boundary of our planetary system. As astronomers observed the new planet though, they eventually realized that something was causing it to speed up and slow down in its orbit. The French astronomer Le Verrier correctly deduced that this was caused by an additional planet in our solar system and predicted its location, and Neptune was thus discovered in 1846.

Since then, astronomers on and off have believed they’ve seen evidence in the motions of the outer planets to hint at other planets lurking out there in the darkness. It was while searching for such a world that Illinois native Clyde Tombaugh found Pluto in 1930. However, it was later realized that Pluto was far too small to be causing any gravitational perturbations and in fact the perturbations themselves didn’t actually exist.

But this is where things get interesting, because it turned out that Pluto was actually simply the first in an entire class of tiny, distant solar system bodies called Kuiper Belt objects. Indeed, it was the discovery of more and more of these objects—some farther away and more distant than Pluto—that eventually caused Pluto to be reclassified as a dwarf planet.

Now, two astronomers from Caltech have published a paper arguing that the orbits of a handful of Kuiper Belt objects show evidence for an even larger body, about the size of Neptune, in the far reaches of the solar system. The reasoning is similar to that which led to the discovery of Neptune: it appears as though a large, massive object is affecting the orbits of these objects. Mathematical modeling indicates these observations could be explained by a ninth planet.

Of course this doesn’t mean that it’s there for sure. That’s how science works: observations provide evidence, and scientists offer a theory or hypothesis to explain it. A good hypothesis is one that can be tested. And that’s exactly what’s happening now: telescopes are being trained toward the outer reaches of the solar system to see if this posited body does indeed exist. If it does, it should be large enough to spot in very large telescopes, despite its enormous distance.

And if it is spotted, the total number of planets in the solar system will go back up to the number we learned in grade school.

This column originally appeared in the Kankakee Daily Journal.

January Skywatch

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This month so far the sky has not been especially friendly for star-gazing. Besides lots of clouds, the big problem with observing in winter is a simple one: it’s cold! In the summer it’s easy to linger at the telescope, waiting for unexpected objects to pass into view or searching for new, hard-to-find targets. In the winter, targets that can be found quickly—before the fingers start to numb—and easily are better.

Fortunately, many of the celestial targets in the January sky are indeed bright and easy to spot quickly. Last month I started with an introduction to the constellation Orion. This month we’ll zoom into some of its telescopic wonders that can be caught on the frigid, (hopefully) clear nights of January.

As I’ve mentioned in this column in the past, I’m partial to observing double and multiple stars with my backyard telescope. These objects are bright enough to find in the light-polluted skies of town, and they’re endlessly varied. The most spectacular object to view in Orion is of course the Great Nebula (which we’ll examine in a moment), but Orion also hosts several lesser-known but lovely and easy multi-star targets.

We’ll start with the easiest target. Mintaka is the westernmost star in Orion’s belt. Through a modest telescope (I usually use a Dobsonian reflecting telescope with a 6-inch aperture) at low magnification (48x), it’s clearly revealed as a wide double star. It doesn’t have the impressive color contrast of a famous pair like Albireo, but with a separation of about 50 arcseconds, it’s easily revealed as a double even in a pair of binoculars.

Things get more impressive swinging the telescope just slightly eastward to the star sigma Orionis, the moderately-bright star visible just beneath Alnitak, the easternmost star in Orion’s Belt. Sigma is actually a triple-star system, with a few other surprises in the field of view. The components of the star are much tighter (closer together) than Mintaka, so I use a higher magnification (60x). The differing colors of this triple star are easily apparent and to my eyes seemed reddish, blueish, and whitish (though part of the fun of observing multiple-star systems is that each observer seems to note different tints). Even more impressive: in the same field of view, just to the west, is another, dimmer triple star system, Struve 761!

Orion_constellation_map

If your fingers are freezing, don’t despair: the next sights are well worth the chill. Move the telescope to the cluster of stars marking Orion’s sword. For now, pass up the Great Nebula (also known as M42) for the star at the southernmost tip of Orion’s sword. This is iota Orionis. Iota is a close pair (separation of 11”, I viewed it at 70x magnification): a bright star with a dim companion. In the same field of view though, is the wider, even pair of Struve 747. But that’s not all: a fainter third double star, Struve 745, can also be spotted in this view.

Finally, the most famous multiple-star system in Orion is buried at the heart of Orion’s most famous sight: the Great Nebula. Just north of iota, you can’t fail to spot it on clear nights. The four stars of the Trapezium are surrounded by the cloudy glow of the Nebula, which extends across the entire field of view in greenish, hazy ribbons. The larger your scope (and the darker your sky) the more detail you’ll see, but even with a 6-inch from my front yard in town, it’s a sight to brave the cold for.

We still have not exhausted Orion’s treasures though. Part of the appeal of searching after double stars is to tackle more challenging pairs: pairs that are either very close to each other or have a significant contrast in brightness. If you’re up for a challenge, try the star lambda Orionis, marking Orion’s head. This is an even double star with a separation of only 4 arcseconds (remember that Mintaka’s components were 50 arcseconds apart). With my 6-inch, I can easily split it on a clear night with a magnification of 70x. Compare this with Rigel, the brilliant star of Orion’s foot. Rigel has a dim companion at a distance of 10 arcseconds, but the brightness of Rigel makes it very hard to spot this pale blue companion star. On my most recent attempt, it took a magnification of 133x to spot it for sure.

I hope I’ve convinced you that Orion is a treasury of sights that make it worth braving the cold this month. Perhaps though you don’t have a telescope to take a look yourself and you’re wondering about the type of instrument to purchase to get started, or maybe you got a telescope this Christmas and you want to know more about how to put it to use. Next month I’ll spend some time going over telescope basics and providing my own thoughts on steps toward easy backyard observing.

This column first appeared in the Kankakee Daily Journal.

December Skywatch

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The evening skies of winter bring one of the most familiar groupings of stars, Orion, known as a giant, hero, or hunter in cultures throughout history and visible at some point of the year from every inhabited portion of the globe. Orion carries within it several stunning sights for both the naked eye and telescope observer, and we’ll be focusing on this constellation both this month and next. In this column I’ll start with a naked eye orientation to the bright constellation, and next month we’ll zoom in on some of the features visible through a telescope.

Orion rises in our evening winter skies as a tilted hour-glass figure marked by brilliant stars. At the beginning of the month he’s well over the horizon in the east by 8:30; by the end of December he’s nearly halfway up the sky in the evening. Two stars mark his shoulders, three his belt, and two his knees. Fainter stars trace out his head, sword, and shield or club he holds extended to the west. Each of the bright stars would be remarkable on their own, but together they make the constellation impossible to miss and twinkle fiercely low in the sky on crisp cold evenings.

The two stars marking Orion’s top shoulders are Betelgeuse (reputed to be a corruption of the Arabic for “Armpit of the Giant”) and Bellatrix (of recent Harry Potter fame—ask a fan what other characters appear in the winter sky). Betelgeuse has an unmistakable pale orange hue, which flickers beautifully when it’s low in the east. The stars in Orion present a snapshot of stellar evolution, and Betelgeuse is the old man in the crowd.

Betelgeuse is a dying star, a red supergiant near the end of its life. During this period of a star’s life it balloons to enormous sizes and can go through periods of instability, its tenuous radius heaving in and out like a slowly beating heart. Betelgeuse is thought to range from a radius of 800 million miles down to 480 million miles, which means at its smallest its surface would still extend beyond the orbit of Jupiter if it took our Sun’s place in our own solar system. Its density though is so low it’s less than a ten-thousandth of the density of the air we breathe, literally a “red hot vacuum.” It’s bleeding off this thin outer atmosphere into space, a dying giant lying just over 500 light years from Earth.

It’s fitting Orion is known as a giant in mythology, because the constellation is full of them. The star marking Orion’s knee opposite Betelgeuse, and providing a bright white-blue contrast to Betelgeuse’s pale orange glow, is Rigel. Rigel is one of the most luminous objects in the entire galaxy, outshining our own Sun by a factor of tens of thousands and at a distance from us of about 750 light years. Though it’s a supergiant like Betelgeuse and therefore has left the “middle age” that characterizes stars like our Sun, it’s younger than the pale orange star. And because more massive stars age more quickly, it’s likely younger than our Sun as well. Supergiants like Rigel (thought to be about fifty times the size and mass of our Sun) live short, hot, bright lives.

The stars in Orion’s belt, going from west to east, are Mintaka, Alnilam, and Alnitak. The star marking the remaining (eastern) knee is Saiph (meaning “Sword” though it’s far from the region of the constellation known as the Sword of Orion). All of these stars are giants or supergiants as well. What makes Orion such a rich area in space for the formation of these bright, young stars?


Image by Mike Hankey, http://www.mikesastrophotos.com/nebula/m42-the-great-orion-nebula/

The answer is the huge clouds of nebulosity that spread throughout this entire constellation, dark and invisible. Though hundreds of times emptier than the best vacuum we can produce on Earth, these clouds stretch for hundreds of light years and contain enough mass to form thousands of Sun-sized stars, as well as a fair amount of giants. And that’s exactly what has been happening for millions of years in this portion of the sky. We can see it in action in the visible part of the cloud, known as the Orion Nebula, a fuzzy smear of light in the center of Orion’s Sword, just below his belt.

We’ll zoom in on this nebula with a telescope next month, but a good pair of binoculars also offers quite a view. In the center of the nebula a tight grouping of four very young stars, known as the Trapezium due to their shape, are causing the surrounding nebula to glow. These gems at the center of the nebula are among the youngest stars visible in the sky, a scarce handful of millions of years old. The nebula that surrounds them is one of the most famous sights in the night sky. Though it lacks the intense color and detail you’ll see in processed images from large telescopes, it’s still quite impressive for backyard scopes.

The astronomy Robert Burnham, Jr., quotes the journalist and astronomer C. E. Barns as saying, “For who would acquire a knowledge of the heavens, let him give up his days and nights to the marvels of Orion. Here may be found every conceivable variation of celestial phenomena: stars, giants and dwarfs; variables, multiples; binaries visual and spectroscopic; clusters wide and condensed; mysterious rayless rifts and nebulae in boundless variety, with the supreme wonder . . . at its heart—the Great nebula.” I tend to agree. Now that we’ve introduced the constellation, next month we’ll take a closer look at what Orion reveals to backyard telescopes.

This column first published in the Kankakee Daily Journal.

November Skywatch

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Cass

This month starts with us relaxing our clocks back into a more natural rhythm with the Earth’s diurnal cycle, as we conclude Daily Saving Time the first Sunday of November and fall back one hour to Standard Time. This means our evenings get darker sooner, and the stars come out earlier for sky-watchers. It also means clock noon and solar noon once again roughly coincide. With evening arriving earlier, this month we’ll continue our series of looking more closely at sky objects that can be seen through sidewalk telescopes even from the streets and backyards of Kankakee.

The bright planets are still mostly grouped in the pre-dawn sky, but evening begins with the constellation Cassiopeia high in the northern sky. This recognizable, easy-to-find constellation hosts a pair of impressive multiple-star systems. Nearby are some lovely clusters and the famous Andromeda Galaxy (often unfortunately washed out by the light pollution in the skies above town).

Cassiopeia is shaped by turns as a 3, a W, an E, or an M depending on its orientation in the northern skies. In the early evening skies of November, it looks like an angular number 3, its bottom pointed down toward the northeast, with five bright stars marking the ends and each angle of its zig-zag shape.

To find our first double star, η (eta) Cassiopeiae, look for a fairly bright star halfway down the second “zag” of the zig-zag number three. This star is one of the most famous binary stars of the night sky. Though it looks like a single star, through a telescope it’s revealed as two stars—a bright yellowish star with a dimmer, reddish companion nearby. Measures of the relative positions of these stars over decades have revealed that this system is actually gravitationally bound, with an orbital period of about five hundred years. The system itself is about 20 light years away, but the two component stars are separated from each other by a distance of only 70 times the distance between the Earth and the Sun,

Once you’ve tried your hand at finding and viewing η Cassiopeiae, the next target in Cassiopeia is ι (iota) Cassiopeiae, a moderately bright star just below the constellation’s southernmost “zag.” Drawing a line through the southernmost two stars of Cassiopeia’s zig-zag, extending again about as far as the distance between the stars, will get you there. Through a telescope, ι Cassiopeiae will look like a smaller version of η Cassiopeiae. In fact though, it’s not a double but a triple system, with the brighter component actually itself a very close double star. Under high magnification and clear viewing, you may be able to just barely spot a small blue companion close to the yellow primary star. This entire triple system is about 160 light years from Earth.

If we go east from the bottom of Cassiopeia, toward the constellation Perseus, we’ll run into the Double Cluster (NGC 869 and 884). Visible with the naked eye in dark skies, these have to be “felt out” in brighter city skies. Once spotted though, they’re still an impressive sight. They are best viewed at lowest magnification in the telescope (or even with a pair of binoculars) and are examples of open or galactic clusters, composed of hundreds of young (six to twelve million years old) stars seven thousand to eight thousand light years away. In the telescope eyepiece they fill the view with dozens of bright, crowded stars.

Now, leaving the best for last (and omitting the fabulous Andromeda Galaxy which is nearby but washed out in city skies), we move to Almach, also known as γ (gamma) Andromedae, to the southeast of Cassiopeia, marking one of the feet of the constellation Andromeda. Almach is one of the most impressive double stars in the sky. Its component stars are a bit closer together than those of η Cassiopeiae but they have a brilliant, sharp color contrast between the yellow/gold primary and the dimmer blue companion star. Like ι Cassiopeiae though, one of the components of Almach (the dimmer blue star) is itself a close double as well, though I have not been able to separate these components in my backyard telescope. It doesn’t stop there though: one of those stars is in addition an even closer binary star with a period of only three days, making the whole system actually a quadruple star system.

I occasionally hear that the early evenings of autumn make people feel winter is finally here and sometimes even lead to seasonal doldrums. I maintain though that darker, earlier evenings are a fantastic opportunity to get out and learn about the dynamic, tangled lives of those bright stars above us. Hopefully these objects give you a place to start!

This column appeared first in the Kankakee Daily Journal.

October Skywatch

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Sorry this is a bit late folks, but here’s my local astronomy column for this month:

This month, the skies favor the early riser. As Saturn slips toward the western horizon in our evening skies, Jupiter, Venus, and Mars take center stage throughout October in the skies before dawn. If you are someone who prefers to rise early, you are in luck. If you’re someone who tends to sleep in, set your alarm and treat yourself to a view of these bright objects at least a few times this month to see the steps in the eastern sky. I’ll give you a breakdown of the performance so you know what particular dates to watch for.

First though, a quick re-cap of the biggest celestial event of last month: the total lunar eclipse, which brought the current tetrad of total eclipses to a conclusion. Last year I had to bribe my astronomy students to rise before dawn to see the eclipse, but this time it was easily visible in the early evening sky. We shut off the lights on our side of campus, set up telescopes around the perimeter of the planetarium, and then waited for the sky—which had been cloudy all day—to clear. It did just in time, and we were able to view the duration of the eclipse in clear, dark skies from the heart of Bourbonnais. It was a sight, I trust, that few students will soon forget. (Several took pictures of the eclipse and have been posting them to social media under the hashtag #OlivetAstro.)

BloodmoonTimeLapse
Time-lapse of the lunar eclipse taken by ONU student Nick Rasmussen.

Now that the Moon is past full, it’s slipped from the evening skies and does not rise until after midnight. Its display isn’t over though, as it moves to the morning sky to join the planets before daybreak as a slender crescent. And that’s the first movement of this act you should catch these October mornings: set your alarm and rise before dawn on either Thursday, the 8th, or Friday, the 9th (or both). If the sky is clear, you’ll see three bright planets strung out in a line pointing down toward the eastern horizon.

The highest and brightest of these is Venus, which rises at about 3 AM and is high in the eastern sky before sunrise. Mars trails it to the east, and below them both is bright Jupiter. On the morning of the 8th, a thin crescent Moon rides just above Venus. By the next morning the Moon has dropped to join Mars and Jupiter as an even thinner crescent lower in the east. The slanted line of the three planets in the morning sky is a powerful illustration of the disk of our solar system, viewed from our tilted angle on the planet Earth.

Moving forward through the month, Venus falls eastward against the background stars each month, while Jupiter and Mars rise farther into the west. Jupiter passes by Mars on the morning of Saturday, the 17th, for the closest conjunction of this planetary arrangement. The bright giant planet passes within half a degree of the ruddy red planet. That’s about the diameter of a full Moon. At that distance, both planets could be visible in the same field of view through a telescope eyepiece.

It’s that ruddy red planet on which NASA scientists last month found the best evidence yet of running water on its surface. They studied the composition of dark tracts on Martian hillsides that change with the seasons and concluded these formed by briny water seeping out and staining the Martian surface.

Finally, as Venus continues its eastward motion against the background stars, it passes by Jupiter on the morning of Sunday, the 25th. Though the two planets are within a degree of each other (twice the diameter of a full Moon), this may be the most conspicuous conjunction of the month, as Jupiter and Venus are the two brightest planets in the sky. On the morning of the 25th and the following morning, they’ll form a brilliant pair with Mars trailing below them to the east.

Of course, their apparent closeness is only an illusion in our sky, the same way the light from a nearby lighthouse might appear close to a ship passing along the horizon. It’s only a matter of perspective. In reality, millions of miles of empty space separate those bright lights in the night.

This column first appeared in the Kankakee Daily Journal.

Planets & Stars

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Planets: Ours and Others: From Earth to ExoplanetsPlanets: Ours and Others: From Earth to Exoplanets by Therese Encrenaz
My rating: 4 of 5 stars

The art of an insightful, timely, and scientifically rigorous overview is a difficult one. This is compounded when the subjects are as broad as planets and stars, respectively. Fortunately for the educated non-specialists, there two slender volumes succeed where many astronomy texts fail: they provide a comprehensive, up-to-date survey of two fields with enough breadth to be useful and accessible to the astronomy educator while retaining enough technical grit for those desiring more depth.

The first volume (Planets), by an atmospheric planetologist at the Paris Observatory, frames the current state of exoplanetary research and the search for life in the context of comparative planetology, starting with Earth and moving through our planetary system.

Beginning with a brief introduction to observing and exploring planets (including exoplanetary detection), Encrenaz moves into a description of theories of planetary formation and then on to the bulk of the book, treating the physical properties of planets. Using Earth as test case and exploring things like geological activity and the water cycle, she provides in-depth comparison of the atmospheres, compositions, and internal structures of the planets of our solar system, touching briefly on some outer-system moons as well.

All of this sets the stage for the final third of the book, a look at exoplanetary systems– their discovery, their properties, and a quick overview of the status of the search for life in the cosmos. The chapters here remind that this is not a book on exoplanets exclusively: rather, it’s a survey of what we know about planets, which any more must include a detailed exposition of the ways other planetary systems are informing this knowledge.

In some respects, this is more helpful than a book on exoplanets alone, allowing an understanding of our own planetary context in light of these new discoveries.

Birth, Evolution and Death of StarsBirth, Evolution and Death of Stars by James Lequeux
My rating: 4 of 5 stars

The second volume is a survey of the physical processes (including a fascinating and detailed analysis of the interstellar medium) governing the life of stars. Lequeux, also of the Paris Observatory, takes a slightly more technical approach. Indeed, it was at times difficult to follow his account of the complex processes taking place within a star at various points in its life cycle.

However, the technical aspects provide a conceptual rigor often glossed over in more popular texts. Topics covered include the birth, physics, evolution, and death of single stars as well as a chapter on the “zoo” of double stars. It concludes with a glimpse of the larger questions of galactic evolution that stellar life and death play into.

Perhaps most importantly, this account discusses the many open questions in stellar evolution, especially star death, and the importance of modeling stellar interiors.

Both books are slender, less than 200 pages each, and filled with diagrams, images, and (especially in Lequeux’s) equations. Both are translations of works originally published in French, and the awkward language at times bears witness to this though never actively detracting from the text.

Neither volume is a textbook (there are no problem sets, for instance), nor are they purely popularizations, maintaining a balance between general survey and in-depth technical treatment. Often I read a survey text and learn nothing new; in contrast, these works are introductions written by active experts in their respective fields, lifting the veil on the physics behind the concepts but keeping a wide and fairly accessible scope, filled with a wealth of new information.

This review first appeared in the September 2015 issue of The Planetarian.

Dwarf Planets and Asteroids: Minor Bodies of the Solar System

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Dwarf Planets and Asteroids: Minor Bodies of the Solar SystemDwarf Planets and Asteroids: Minor Bodies of the Solar System by Thomas Wm. Hamilton
My rating: 3 of 5 stars

My first research project as an undergraduate was attempting to determine orbital parameters of some asteroids. I remember being fascinated by these obscure bodies and their mysterious classical names. If I had Dr. Hamilton’s slender volume at that time, some of my questions would have been answered.

The minor bodies of the solar system are an eclectic group with interesting histories, and Hamilton’s volume cracks the door onto this subject. The book (under 70 pages) gives a brief introduction to asteroids (nine pages), but is primarily a catalogue of information– physical characteristics, orbital data, and explanation of name and discovery– for select bodies. There is a lot of interesting information here, but unfortunately none of it is referenced. One example: according to Hamilton, asteroids 300 Geraldina was named by Auguste Charlois, an apparently prodigious asteroid-discoverer who was murdered by a former brother-in-law. There’s obviously a story here, but without references the reader is left with no avenue by which to learn more.

Worse yet is the omission of information related to the objects themselves. Dwarf planets are mentioned (and distinguished by bolding their names), but there is no discussion of their distinction from asteroids. Comets are mentioned without any explanation of how they differ from asteroids and dwarf planets and what this indicates about the physical nature of the solar system. The Yarkovsky Effect is mentioned three separate times without an explanation of what it is.

Finishing the book, I was left with far more questions than I had upon beginning it. Why do some asteroids discovered later have lower numbers than those discovered earlier (i.e., 6312 Robheinlein and 6470 Aldrin, for instance)? Why do some have names consisting of only numbers and letters (2012VP113, for example)? Is Quaoar officially considered a dwarf planet?

A simple response to these might be, “Look it up and find out,” but this leads to my major question regarding this book: in a day when I imagine information about all minor planets is available online somewhere (another reference that would have been helpful in this book), why publish a book with limited information about only a selection of asteroids? It might look on the observatory shelf, but as a catalogue it is inherently incomplete and immediately out of date.

This review first appeared in the September 2015 issue of The Planetarian.