Good Morning! Hopefully you’re reading this at least 90 minutes before sunrise on Thursday, October 8*.
UPDATE 7AM: The relative positions of Saturn and Mercury have changed since yesterday. Saturn is now above Mercury, still a bit to the left. So the graphic below is a bit off. Supposedly today (10/8) was when the 2 were to be closest, but they appeared closer yesterday. BTW, Saturn's rings are visible (barely) through 10 x 42 binoculars.
*If not, you can probably see pretty much the same thing for a few more days, but today is as close as Mercury and Saturn are going to get.
Here’s the deal. If you can get outside, and to an unobstructed Eastward view by ~an hour prior to sunrise* (so by 6:30AM MDT along the Wasatch Front) you’ll see 3 planets, all close together: Venus, Mercury, and Saturn. They’ll look like this, but the first thing you’ll look for is Venus.
*Yeah I know yesterday I said 45 minutes, but I checked the tables: sunrise today in Salt Lake is 7:32AM, and best viewing yesterday was ~6:35AM.
Venus is- after the Sun and the Moon- the brightest object in the sky. When it’s up, it is always the absolute brightest star. It’s always fairly low in the sky*, on the same side of the sky where the sun either just set, or is about to rise. This makes sense if you think about it for just 5 seconds. Venus is closer to the Sun than Earth. It can’t be on the “other” side of the sky, ever. Right now Venus is preceding the Sun, so you can see it just before sunrise, but not after sunset. Look East and very slightly Southeast**, find the super-bright “star”. That’s Venus.
*Always below 47 degrees.
**Sunrise azimuth today = 97 degrees.
Side Note: BTW, Jupiter is still easily visible after sunset. A little higher than when I did the post, but if anything easier to check out. Last night all 4 Galilean moons were visible, 3 left, 1 right.
Extra-Help: OK, so you can’t figure out East, and don’t have a compass? No problem. Look up in the sky. Find Orion (pic right). It’s the big constellation that looks like a guy with a bow and a sword hanging from his waist. At 6:30AM right now it’s more or less due South. Look at it, then rotate about 80 degrees or so to your left. Can’t find Orion? No problem. Look at the Big Dipper*. At 6:30AM it’ll be on its side, about ~30 degrees or so East of true North. Rotate ~70 degrees to your right.
*Can’t find the Big Dipper? Seriously, you can’t find the Big Dipper? Really?? Sorry, this blog just isn’t going to work for you…
Tangent: The night sky makes a great compass and clock, and you hardly need to know any stars, and really just 2 constellations- Big Dipper and Cassiopeia. I was going to get into it here, but time is limited. I’ll cover it in another post.
So you’re looking at Venus. Venus is, in many ways, the planet most similar to Earth. It has a solid surface, is nearly the same size, has almost the same gravity… oh wait a minute…
Tangent: You’re tuning out. I can tell. You’re like, “Oh, the planets- Mercury, Venus, Neptune, whatever… who cares?” I’ll tell you who should care: you. Not just because they’re super-cool- and they are- but here’s another reason, specifically for readers who believe in God.
Special Message For Theist-Readers
OK, so you believe in God. Presumably, you also believe that someday- like after you die- you’re going to meet God. You’ll meet him, he’ll be there with his long white beard and flowing robes, and he’ll pass judgment on you or what-not. But think about it. Do you think he’ll just look at you, pass judgment, and that’s it? Frankly, I doubt it. You spent your whole, long life here on Earth, and now you finally meet the creator of the universe, and get to actually talk to him, and find out the answers to all the big questions and the meaning of life and, well… everything! I expect that first, there’s going to be some chit-chat, maybe even some small-talk.
God will probably ask you about your death, and maybe your family and kids, and maybe you’ll talk about your career or other stuff. And you- like any good guest- will ask God about how he’s doing and Heaven and such, and at some point the conversation will almost certainly come around to God’s most amazing creation- the universe. He’ll probably ask you what you think of it, and what your favorite parts are, and he’ll probably expect that given you spent like 80 years right under them every night you have some knowledge of and opinions about, the planets, since they’re the most obvious, closest, easily-observable heavenly bodies in the sky. Now imagine how unbelievably freaking awkward you’re going to feel when God realizes that you never even bothered to learn the names and order of the planets, much less try to find them in the sky. Seriously, you don’t want to be embarrassed like that. Not on your judgment day.
Nested Tangent: I have to come clean and admit that the idea of post-mortem chit-chat with a supernatural being is not original. I actually got the idea from an old joke. In fact, it’s pretty much my Favorite Joke Ever. What’s that? You’d like to hear it? OK, but be warned- the joke involves Satan, substance abuse and homosexuality, so if these topics offend you, just skip ahead right now…
So this guy dies after not having lived a very good life and he goes to Hell. So his first day in Hell, he reports to Satan’s office for his orientation interview.
SATAN: Welcome, welcome, please have a seat. Welcome to Hell!
GUY: (sits down)
SATAN: You know, Hell gets a bad rap, and a lot of new arrivals are all nervous about it, but it’s really not accurate at all. There are lots of great things about Hell.
GUY: (rolling his eyes) Oh sure, right…
SATAN: No, really. Let me ask you something- do you smoke?
GUY: Well yeah, I did smoke and it’s probably one of the reasons I died when I did…
SATAN: Great! Then you’re gonna love Mondays. Monday is Smoker’s Day. We have all kinds of tobacco- cigarettes, pipes, chew, Cuban cigars, all the best stuff, all free and because you’re already dead, you can’t hurt your lungs!
GUY: Well, I guess that’s OK…
SATAN: That’s not all! Let me ask you something else- do you drink?
GUY: Well yeah, I did drink and in fact most days I started around…
SATAN: Great! Then you’re gonna love Tuesdays. Tuesday is Drunk Day! We have all kinds of alcohol- beer, wine, gin, tequila, single-malt scotch, all the best stuff, all free and because you’re already dead, you can’t hurt your liver!
GUY: Well, hey, that sounds pretty good!
SATAN: That’s not all! Let me ask you something else (with a conspiratorial wink)- do you like to do drugs?
GUY: Well on occasion I did indulge in recreational…
SATAN: Great! Then you’re gonna love Wednesdays! Because Wednesday is Drug Day. We have all kinds of drugs- pot, cocaine, crack, heroin, meth, all top-grade, all free, and because you’re already dead, you can’t hurt your brain!
GUY: WOW! That sounds awesome!!
SATAN: And that’s not all! Let me ask you something else- are you gay?
GUY: Uh, no.
SATAN: Oh. Well you’re gonna hate Thursdays…
Venus (left) has the most perfect orbit of any planet in the solar system. The orbits of all planets are elliptical (see this post) but Venus’ is the most nearly circular. Something even more unique about the planet is its rotation: it rotates backwards, the only planet in solar system to rotate West-to East, which is called retrograde. And it rotates slowly, taking 243 of our days to complete one rotation, which is longer than its year, at 224 Earth-days. But because the year is longer than the “day”, the apparent day- from one sunrise to the next- is much shorter to an observer on the surface- only 117 Earth-days (think about it- it makes sense.)
Venus lacks a magnetic field, for reasons not entirely clear*, so if you were standing on the surface (pic right from Soviet Venera lander, 1985) your compass wouldn’t work. But that would be the least of your problems. First, you be crushed like an egg. The air pressure on the surface is an astounding 1,352 psi, which is 92 times the sea-level air pressure here on Earth, or equivalent to more than half a mile under water! And if somehow you weren’t crushed, you’d be cooked/melted/vaporized in seconds; the surface temp averages around 860F, a result of the runaway greenhouse effect in Venus’ overwhelmingly CO2 atmosphere.
*Probably lack of convection in the interior, maybe due to a super-heated mantle.
Next Up – Mercury
From Venus, look down a bit and slightly left. The bright(er) “star” you see is Mercury (left). Mercury is even closer to the sun, and further from Earth, and smaller than Venus so it’s generally harder to see- it’s always real close to the Sun. Mercury’s pretty small- only about twice the volume of the Moon- and like the Moon it’s too small to retain any real atmosphere. It’s orbit is pretty eccentric (elliptical) but it has virtually no axial tilt- it is the most “upright” planet in the solar system, meaning that Mercury has no “seasons” in the traditional sense.
For a long time astronomers thought that Mercury was tidally locked (explained in this post) to the Sun, with a permanent, boiling-hot light-side and a freezing-cold dark side. But it turns out that Mercury is actually in a stable orbital resonance* (explained in same post) with the sun with a 3:2 ratio, meaning that Mercury rotates 3 times for every 2 times it rotates around the Sun**.
*The math is beyond the scope of this post, but the resonance is believed to be stable because Mercury’s orbit is so elliptical.
**Mercury’s year = 88 Earth-days.
All About Saturn
Slightly below and left of Mercury yesterday- although today they’re practically on top of one another- is another, much fainter “star”- Saturn. Saturn (left) is a gas giant, the second biggest planet in the solar system, with similar composition and (presumably) structure as Jupiter, but it’s also- in my opinion- the 2nd coolest planet in the Solar System. Here’s why:
Rings. Saturn’s rings are- hands-down- the absolute coolest-looking thing for a billion miles in any direction. When the planet’s tilted a bit relative to us* they’re easy to see with almost any telescope or even good binoculars. Guess what they’re made of? Water-ice. 93% anyway, the rest mostly Carbon. They’re an amazing 70,000 miles wide (from innermost to outermost ring) but only- get this- 20 meters thick! That’s like- proportionally- 2,000 times thinner than a sheet of copier paper*!
*My calculation. Could be wrong.
The bad news is that you almost certainly won’t see the rings this morning. The rings are tipped only about 2 degrees* toward us (North-side visible) right now, and in the dawn light I doubt you could pick them out even with a decent scope. The gaps in the rings, BTW are caused by a series of orbital resonances with several of Saturn’s moons. And speaking of moons…
*Saturn has an axial tilt of almost 27 degrees, which means that much of the time we can see the rings quite well.
Moons. Saturn has 61 moons, most of them little teensy things, but 13 of them good sized, including Titan, the most amazing moon in the solar system. It’s nearly the largest* and the only moon to have a substantial atmosphere (mostly nitrogen) and the only planetary body besides Earth known to have “lakes” in this case of liquid methane.
*Ganymede, which we talked about in this post**, is bigger. Like Ganymede, Titan is tidally locked to its planet.
**It’s like, I have a post for everything.
Side Note: I may have spotted Titan through my scope once, several years ago, still not sure. In any case, you won’t see it tomorrow.
OK, that’s all I got. But 3 planets, and my Favorite Joke Ever- wasn’t that worth waking up early for?