AstroUpdate: Aldebaran, Ain, Auriga, Anticenter, Andromeda

Today is it- the Winter Solstice*- which means the days are short and the nights are long. Hey, that’s a line from a song*, isn’t it? That’s funny, because this post will have not one, but two music videos. Anyway, there are really only 3 fun things to do on long nights. The first of course is night-ride, which isn’t that great with a mess of crusty snow & ice all over the trails, the second I can’t write about in a family blog, and the third is stargazing.

*No, this post has nothing to do with it. If you want a post about the Winter Solstice, check out this post or this post from last year.

**California Sun. I’m partial to the Ramones cover.

Back in October, I kicked off AstroWeek with a quick overview of navigating and telling time by the night sky. The navigation part is still simple-as-pie: locate the Big Dipper and/or Cassiopeia, and use them to find the North Star. The clock part is simple too, but if you haven’t been keeping up with it, you should be aware that the clock as has advanced. Remember, the Earth rotates around the Sun in a counterclockwise direction, when viewed from the North, or “above” the solar plane. And the Earth rotates in the same direction. So every night as dusk, throughout the year, the entire night sky will be tilted just a titch more to the West. Over the course of a few days or a week this isn’t really noticeable, but after a couple of months it makes quite a difference.

At around 8PM in Salt Lake City Cassiopeia is at the top of the clock, an upside-down “W” above and South of Polaris. The Big Dipper is down way low in the sky, and- in much of the valley- completely obscured by the foothills.

At 6AM, the Dipper is high up and upside-down, at around the 1 o’clock position in the sky, and Cassiopeia is low and largely obscured.

The “advance” of the sky means that many of the constellations we had to stay up late to see in October are now easily viewable just after dinner. The Pleiades, for example, are already high in the sky when darkness hits, and by 8PM Orion is clearing the Wasatch. By 6AM Orion will be setting in the West and the Pleiades already out of view.

Orion is where we wrapped up AstroWeek, and so it’s a good place to pick up again. We’re going to start with a constellation that’s above Orion, but first, since we’ve got such a nice early evening view of both Orion and the Pleiades, let’s quickly check out some neat, easy-to-locate stuff in between them.

Aldebaran

About mid-way in between Orion and the Pleiades is one really bright star. If you check it out with binoculars you’ll see it’s a beautiful, bright orange, similar to Betelgeuse. This is Aldebaran, a red giant with a diameter 44 times that of our sun. For perspective, if you stuck Aldebaran in the position of our sun, it would be as though the sun covered 20 degrees of the sky*. Speaking of the sun, Aldebaran lies close (from our view) to the ecliptic, and the Sun passes just barely North of it right around June 1. It also regularly gets blocked, or occulted (eclipsed) by the Moon.**

*Of course, we’d be totally cooked, so we wouldn’t be “seeing” much of anything…

**I think the next such “eclipse” is in 2015, but I need to confirm that.

Aldebaran is the “eye” of- and brightest star in- the constellation Taurus, which is one of those lame constellations that looks absolutely nothing like what it’s supposed to be- a bull. But for years before I knew what it was, or where Taurus lay in the sky, I recognized it as the “Orange Linker” because of its “hub” position relative to Orion, the Pleiades, and the next constellation we’ll check out- Auriga.

All About The Hyades

But before we leave Aldebaran, there are a whole bunch of interesting stars right around it, mainly on the Pleiades-side: the Hyades. The Hyades are the closest and best-studied open cluster of stars to us, a tight grouping of some 300-400 hot, blue-white stars of similar composition* 151 light years away. Aldebaran, BTW, is not part of the Hyades, and has a very different composition, but just happens to lie along the line of sight to the cluster.

*Rich in metals, about 40% more so than our sun.

The “core” of the Hyades, though small, is one of my favorite constellations- tight, beautiful and amazingly symmetrical. (In urban areas you need binoculars to spot this; in remote desert/mountain areas it’s easily visible without.) It’s just to the West of Aldebaran, slightly South of the most direct line from that star to the Pleiades. I call it the “Space Invader”, as it reminds me of the landing craft from the same-named 1980’s arcade/video game.

All About Ain

But the coolest star in the Hyades is just a titch further West and slightly North of the Aldebaran-Pleiades axis. This is Ain, sometimes considered the “other eye” of the bull, and usually naked-eye visible even in the valley. Ain is the brightest star in the Hyades proper, one of 4 dying blue-white giants that is currently fusing helium intro carbon in its core, having long ago fused its core hydrogen. It’s about 13 times as big, and 2 ½ times as massive, as our sun. But what makes Ain cool is that it’s one of* the easier stars to spot which we know has a planet orbiting it. The planet is a “hot giant”, more than 7 times as massive as Jupiter, but orbiting it’s hotter, bigger, brighter “sun” much more closely- only twice as far as Earth lies from Sol. The view from such a planet- if one could see the sky- must be astounding. The sun would appear 7 times the size of ours in the daytime sky, while the night would be light up by the hundreds of spectacular nearby stars of the surrounding cluster. Imagine our night sky filled with 300-400 stars as bright- or brighter- than Sirius!

*The easiest- that I know of- is Pollux, in Gemini, which we’ll cover in a future post.

OK, this is all cool stuff, but it’s actually not what I wanted to blog about. Let’s get back to Orion. “Tilt” your view of the sky so that Orion is standing straight up. (Around midnight right now this is already the case if you just look South.) Now look up and slightly to the right/West, pretty much directly above Aldebaran. You’ll see a clear, large pentagon of stars. (At 8 PM, it’ll appear on its side and left of sideways-Orion, later on it appears above upright-Orion.) This is Auriga. Like most constellations, it looks nothing like what it supposedly is- a charioteer. I just think of it as “the Pentagon” and as such it’s easy to recognize. Because of its position- higher than Orion but lower than Cassiopeia, it’s easy to pick out all Winter long, through most of the night. (When I camp down by Gooseberry/Little Creek in Winter, Auriga is usually the first thing I recognize in the sky.)

All About Auriga

The brightest star in Auriga, or the left shoulder (it’s left, your right) of the upright-pentagon, is Capella, the brightest-Northest star, or in astronomical terms, the first-magnitude star closest to the Celestial North Pole. It’s a fairly close neighbor, only 43 light years away, and it’s a double- a big double- but the two stars are too close to pick apart even with a telescope*. The 2 stars are 14 and 8 times the size of our own sun, respectively**, and are really close together- as far apart as Venus is from our Sun- orbiting each other just every 104 days. The smaller of the 2 has a dead helium core which hasn’t yet start to fuse into carbon, but helium fusion is well underway in the bigger star; when it completes it will expand again, possibly bumping/engulfing the smaller partner.

*The kind you or I would buy, anyway. Hubble can pick them apart.

**Though only 3 and 2.5 times the mass.

Across the Pentagon, to its “lower-right” foot when upright (your left) is Alnath (or “Elnath”), which actually links Auriga to Taurus. 130 light-years away, it’s in the final stages of hydrogen fusion and within only a couple million years will expand and turn bright orange. But the cool thing about Alnath/Elnath is this: It appears in the sky just 3 degrees from the Galactic Anticenter.

The Galactic What? The Anticenter isn’t a place, but a direction. It’s the exact opposite direction of the very center of the Milky Way Galaxy, which lies is Sagittarius, and so isn’t visible in Winter. But it you look up at Auriga’s “right (your left) foot”, then look exactly 180 degrees away into the ground, you’re looking toward the center of the galaxy.

The Galactic Center and Anticenter are cool because they give you some easy perspective. Space can be a little disorienting. We think most often in terms of terrestrial North and South, but since our axis is tilted 23 degrees relative to the ecliptic, our perspective is already somewhat messed up. The moon lies roughly on the ecliptic, though ranging as far off as 6 degrees, but the ecliptic itself is tilted at 60 degrees relative to the galactic plane. In other words, our whole darn solar system is tilted sideways.

But on a clear night, you can see the galactic plane clearly as the “Milky Way”. In December at 8PM it stretches from Auriga in the East, up to Cassiopeia overhead, to Cygnus- the swan or “Northern Cross”* to Aquila- the eagle- and down into the Western Horizon. Even if you’re in a city and can’t make out the Milky Way, if you can just pick out Auriga and Cassiopeia, you can visualize the galactic plane, and know what’s “up” and “down” in the big picture.

*Another constellation we’ll check out in a future post, featuring the fabulous star Deneb.

So that’s cool, but it leads to the bigger question: Where is the center of the whole universe? You know, where the Big Bang happened? Because the Big Bang happened at a single point and then everything exploded out of it, right? So where’s the point?

Unfortunately, I can’t point you to the center of the universe because there isn’t a center. Or rather, everywhere’s the center. There’s a tendency to think of the Big Bang as a point in space, but that’s not right; space was a point- there was nothing outside of it. This is weird and non-intuitive, but that’s how relativity works. If this frustrates you, remember: the human brain evolved to understand things how they function at our scale, in our surroundings. It didn’t evolve to understand how things really are, on a cosmic scale. It’s the dog-and-the-diesel-engine thing.

So I can’t give you the center of the universe. But as a consolation prize, I’ll give you the center of the Local Group- the cluster of 30+ galaxies of which our own galaxy is a part.

Let’s go back to Cassiopeia. Orient yourself so that the W is upright, and the North Star above it*. Go down below the W, about ½ the distance between the W and the North Star, and you’ll see a string of somewhat evenly spaced bright stars in a gently curving line from Northwest to Southeast. This is Andromeda.

*My directions in this section assume observation around 7-11PM in mid-December.

All About Andromeda

Tangent: Andromeda is of course named for the princess in Greek Mythology. She was the daughter of Cepheus (who has his own constellation, north of Cassiopeia) and Cassiopeia (namesake of the Big W), King and Queen of Aethiopa*. Cassiopeia bragged that she was more beautiful than the Nereids, the daughters of Poseidon, God of the sea. Poseidon in anger sent a sea-monster- named Cetus- to ravage the Aethiopian coast. Cepheus consulted the Oracle, who- never a bearer of cheery news- told him that he could only save his nation by sacrificing his daughter to the sea-monster. Cepheus and Cassiopeia had Andromeda chained to a rock, naked, on the shore.

*Which was apparently not “Ethiopia”, but rather somewhere around Phoenicia, or modern-day Lebanon.

Nested Tangent: Cassiopeia, Clytemnestra, Helen, Hera- has anyone else noticed that Greek mythology is chock-full of high-maintenance, temperamental, problematic wives? Seems unfair, huh? Guess what: I’m Greek-American, spent a decade+ in Greek Orthodox Church/Sunday School and have ~ dozen female Greek-American cousins, and though I recognize this is a terrible, gross, unfair generalization, I am convinced that there is a kernel of truth in this- Greek women tend to be problematic and high-maintenance. (Fast Jimmy, if you are reading this, back me up- you know it’s true.)

Meanwhile, the hero Perseus happened to be flying past with a head in a bag. He was flying with the aid of winged sandals, loaned to him by Hermes, messenger* of the Gods, and the head belonged to the Medusa, a female monster who he’d recently slain, and who was so hideous that simply gazing upon her face would turn you into stone. Perseus, seeing the naked princess chained to a rock and the hungry sea-monster approaching, swooped down, told Andromeda to look away, whipped the head out of the bag, and turned Cetus into stone. Perseus then freed Andromeda, flew her home and married her. At the wedding, her Uncle Phineus, to whom she’d been promised**, made a scene whereupon Perseus, still in possession of the Medusa’s head, turned him into stone as well.

*Even back when I first heard these myths, ~20 years before cell phones, I thought it was way lame that the gods needed a messenger. They’re gods- don’t they have like telepathic powers?

**Yuck. Seems like every mythology has incest stories. Lot, Oedipus, Cronus & Rhea- yuck, yuck, yuck.

Nested Tangent: What I just love about Perseus is that the guy is always thinking ahead. Seriously, if you or I managed to slay a monster like the Medusa, we’d be like, “Phew! Glad that’s done with- let’s get out of here!” But Perseus thinks, “Hey. I should bring this head along, just in case I need to turn anything into stone…” And talk about prepared- he even brought the head to his wedding!

The Andromeda story is fascinating not just in its own right, but because of the obvious parallel in Hebrew mythology, and yes I’m talking about Abraham and the near-sacrifice of Isaac.

Side Note: This is hardly the only parallel between the two mythologies; Deucalion- who survived a God-induced deluge by building an ark- is one of the most obvious. Several other Indo-European mythologies- including Babylonian, Sumerian and Hindu- also included Flood legends. One hypothesis is that the story originated from a rapid filling of the Black Sea basin. Then again, flood legends exist in Apache, Mayan, Navajo and Yakima mythologies, so maybe such legends originated from the few- hundred-foot rise in sea-level at the end of the last ice age…

It’s interesting to compare the 2 stories side-by-side, because there are a number of really interesting differences:

1. The Setup. The Greek version goes to great pains to provide a justification for the sacrifice. Though Yahweh and Poseidon both act- for supernatural beings- like petulant jerks, the back-story of Cassiopeia’s bragging provides at least some (half-assed) justification for Poseidon’s dispatch of the sea-monster and sacrifice-demand. Yahweh, on the other hand presents his demand for sacrifice as essentially nothing more than a nihilistic loyalty-test.

The reaction of the fathers in each story differs as well. Cepheus is positioned as choosing the lives of his subjects over the life of his daughter. Though a distasteful choice, it’s logical, and perhaps even coldly admirable. But Abraham isn’t saving anyone by sacrificing Isaac; he’s just following orders. By any standard of civilized modern ethics, his action is repugnant, and a present-day reader can’t help but observe that a man who’d follow a god’s instructions to kill his own child would likely follow his instructions to fly an airplane into a skyscraper…

The ethics of both gods are lousy by modern standards in that they require an innocent to suffer for the sins or beliefs of their parents. Think about that, and think about the worst criminals in modern history. None of us would suggest that the offspring or other family members of Ted Bundy or Timothy McVeigh be punished for crimes committed by them.*

*”Them” being Bundy and McVeigh, not their family members.

Side Note: Want an example of a modern-day society that does exact punishment upon offspring? North Korea. For a gripping, modern day account of such punishment, check out The Aquariums of Pyongyang, the page-turning memoir of Kang Chol-hwan, who, as a young boy, was imprisoned in a hard-labor camp for a decade due to the alleged political crimes of his grandfather.

2. The Scene. The Greek version is- let’s face it- way hotter. I heard both stories when I was probably 8 or 9 years old*, and even then, I knew that naked princesses chained to rocks was saucy stuff. Throw in a sea-monster, a flying hero and royalty, and the Greek story beat the Hebrew one hands-down.

*I believe- but can’t prove- that Greek-American kids generally hear the Greek myths at an earlier age than “Other-American” kids. In my case, I learned Greek myths and Bible stories around the same time.

3. The Resolution. This may seem trivial, but it’s the biggest distinction. Although neither child is ultimately sacrificed*, Isaac is saved through submission to God, while Andromeda is saved through human defiance, courage and ingenuity. Guess which ending I prefer?

*Greek mythology does of course include a well-known story of a child who is sacrificed- Iphigenia (Agamemnon’s daughter)- which kicks off the Orestes cycle, which- in my opinion- is the Best Story Ever.

It’s pretty obvious at this point, but I’ll say it anyway: I don’t care much for the Abraham-Isaac story- it’s the Bible at its near-worst*. The Bible is filled** with stories of admirable ethics and compassion and wisdom, but this ain’t one of ‘em. Oh, sure, Yahweh spared Isaac alright, but it’s hard to see that as particularly compassionate or good. If I held you up at gunpoint, took your money, but then changed my mind and returned it, that would be all well and good, but wouldn’t it be a whole lot more good if I didn’t hold you up in the first place?

*It’s hard to beat the massacre following Joshua’s conquest of Jericho.

**Well, the New Testament is anyway. Funny how so many modern-day “Christians” seem to draw supporting passages for their political beliefs- gay marriage, capital punishment, gun control- overwhelmingly from the Old Testament, and forget all that stuff about camels and needles and cheeks…

Andromeda is full of spectacular stars. Arguably the most stunning is Almach, or Gamma Andromedae, a double visible through a moderate-power telescope*. The 2 stars are stunning together, the brighter one golden-yellow and the smaller greenish blue. The smaller star is actually a double as well, and then within that pair, the larger is a double yet again, so the whole system is quadruple, in the form of a double-within-a-double-within-a-double. Wow.

*And supposedly through binoculars, though I couldn’t separate them when viewing from my yard.

Tangent: I tried to obtain an actual photo of Almach for this post (pic right = one I pulled off the web). The housemate of a coworker- let’s call him “Aaron”*- has a scope powerful enough to get the shot. But we were unable to work out a clear night this past weekend. I went to bug Aaron about it Friday afternoon at work. I felt bad bugging him during work hours, because Aaron works upstairs in IT, and as everybody knows, IT guys work really hard and are super-busy, right?

*”Aaron” is the coworker, not the roommate. Let’s call him (the housemate) “Justin.”

But I really wanted to get time on the big scope, so I overcame my reticence and headed upstairs late Friday afternoon. As you can see, Aaron was pretty busy, working hard with his boss- let’s call him “Scott”- seated at the desk.

Anyway, Aaron was very accommodating, but weather and schedules didn’t cooperate.

But to find the center of the Local Group, let’s move back one star along the right/West to Mirach, or Beta Andromedae, a bright orange/red giant 200 light years away. (From this point on, you’ll need binoculars in light-polluted areas. On a clear backcountry night, you might do without if your eyes are sharp.) From Mirach, follow up to the North side of the constellation to the next bright star (Mu Andromedae, white dwarf, 136 light-years away.) Next continue in the same direction, but slightly left/East an equal distance again to the next bright star (Nu Andromeda, double star, 680 light-years away. Cool factoid: the 2 stars of Nu Andromeda appear to be tidally locked, always presenting the same face to one another.)

From Nu Andromeda, move just a titch to the right/East. You’ll see a dim little ball of white fuzz. This is it- the farthest thing in the night sky visible with the naked eye- the Andromeda Galaxy, 2.5 million light-years away. If stars were marbles, and Sirius lay 2 feet away, Andromeda would be in Wendover*.

*My calculation, could be wrong. I just wanted to work Wendover into the post.

We’re Number 2

The Milky Way is the second-largest galaxy in the local group. #1 is Andromeda. # 3, not visible with the naked eye, is the Triangulum Galaxy (not visible with the naked eye), which lies directly opposite from Milnach as Andromeda, at about the same distance in the sky. These 3 galaxies- Andromeda, Milky Way, Triangulum, are the big spirals of the Local Group; everything else is chump change in comparison. Andromeda and Triangulum are much closer to one another than either is to us, so the “center” of the local group is somewhere in the general direction of Milnach, roughly ~1.7 – 2.0M light years away. Look in that direction, and you’re looking at the center of something really big.

We made it. This week the days will start getting longer, but we’ve got months of great winter stargazing ahead. I’ll try to check in with monthly updates through the season similar to this one. Given work, holiday and family commitments this week, I probably won’t post again till after Christmas. Have a great holiday.