Wednesday, November 23, 2011

Remember Where We Parked!

If you've tried out my two previous blog posts on how to be a Moon map expert, you're now quite ready to be a Certifiable Lunar Historian when it comes to knowing where all the Apollo Lunar Modules landed. It's a snap, because (1) there are only six lunar landing sites and (b) the maria you already know will help you pinpoint the landing sites quite easily.

The Apollo lunar landing missions were numbered 11-17. If you saw the movie, you already know that Apollo 13 wasn't able to land on the Moon, so all we have to think about are the remaining missions: 11,12, 14, 15, 16, and 17.

Everybody knows that Apollo 11 landed in the Sea of Tranquility, and we'll get into more detail about that shortly. Let's split the remaining missions after Apollo 11 into "odds" and "evens" :

So, we've got the even-numbered missions on the lower left, the odd-numbered missions up above, and the Apollo 11 mission right in the middle as sort of a "divider." It's funny, but the layout is pretty darned close to how the actual landings occurred back then.

You know where Apollo 11 landed, right? "Tranquility Base," on the Sea of Tranquility. Let's go back to the Moon map and look at the Sea of Tranquility again:

As you remember, it's right in between the Seas of Serenity and Fertility, right? (STuF). The Sea of Tranquility straddles the Moon's equator, which is fortunate, because Apollo 11 relied on an equatorial orbit when it arrived at the Moon. Landing on the equator would make things a lot easier for fuel consumption and communications back to Earth, so Mission Control picked out a smooth spot on the Sea of Tranquility that's right on the equator. Let's look at the map with an equator drawn on it so you can see where the landing was:

See? Right on the equator, at the bottom left corner of the Sea of Tranquility is where Neil Armstrong and Buzz Aldrin landed. All you have to do to find the landing site when you're looking at the Moon is to find the Sea of Tranquility (which you know how to do already) and then look at the 7 o'clock position of the mare - - THAT'S Apollo 11.

Let's go on to the next two landings, 12 and 14. Both of these ships landed in what's called the "Known Sea" or Mare Cognitum. The reason the sea was named the "Known Sea" is because so many lunar missions (manned and unmanned) arrived on this expanse of flatlands on the west side of the Moon. In fact, part of Apollo 12's mission was to set down next to an earlier unmmaned probe named Surveyor 3, a feat which Pete Conrad and Al Bean achieved in November of 1969:

The landing site for Apollo 12 was right where the Known Sea bumps into the Ocean of Storms, just south of the equator:
Once again, we skip over Apollo 13 because that mission didn't put anyone on the Moon, thank goodness. The next mission, Apollo 14, landed on the east side of the Known Sea, next to a huge, ancient crater called Fra Mauro. This mission was also south of the equator:

The final three Apollo missions were much more ambitious. While the earlier missions were near the equator and aimed for smooth, flat landing targets, the later Apollos were sent to the highlands of the Moon. The Apollo 15, 16, and 17 crews were outfitted with larger fuel capacity LMs, to fly further away from equatorial sites and carry more gear to the surface. They even had lunar rover vehicles with them to extend their surface activity areas. 

I'm going skip Apollo 15 for a moment so we can finish up the even-numbered flights. Apollo 16 landed in a highland area almost 10° south of the equator, near a rugged crater named Descartes. If you draw a line straight south from the bottom of the Sea of Serenity, the Apollo 16 landing site is about even with the north side of the Sea of Nectar:

Apollo 15 and Apollo 17, the only missions north of the equator, have easy-to-remember landing sites because they both landed next to the Sea of Serenity. Apollo 15 set down in-between the Sea of Showers and the Sea of Serenity, in an area called the Hadley-Apennine Mountains. It's really easy to spot if you look right at the middle of the northern half of the Moon.

The final mission landing site, Apollo 17, is as easy to spot as Apollo 15's locale, because it's also stuck at the intersection of two maria. In this case, Apollo 17 landed in the Valley of Taurus-Littrow, where the Sea of Serenity bumps into the Sea of Tranquility: 

And that's it! Just remember that Apollo 11 landed on the equator, all the even-numbered Apollos after that landed to the south and west, and all the odd-numbered missions landed to the north around the Sea of Serenity.

The crew of Apollo 17 left the Moon in December of 1972, and nobody's been back since. Hopefully there will be more landing sites to memorize soon, instead of just the six dots that mark mankind's furthest steps away from Earth.

Thursday, November 10, 2011

Be a Moon Expert! - Part 2

You're half an expert on Moon geography already - - so let's get the rest of the Moon into your head right away.

Quick technical review: the maria are the dark splotches we see on the Moon. The maria are spread out over the whole Moon in an easy-to-remember pattern:

"Five on the East Side,
Five on the West Side,
Two in the Middle
and an Ocean out West"

Last time, we went over the East (right-hand) side of the Moon, where there are FIVE maria: the Sea of Crises in the East, then then three "ity" maria in the middle East (Serenity, Tranquility, and Fertility -- "STuF," remember?), and then the Sea of Nectar, "dripping" at the bottom of the East side of the Moon.

Let's take a look at the Moon again:

Okay, we did the East side, and we'll do the West side - - but first, let's make a note of the two maria
that aren't East or West - - they're right in the middle, see?

Let's pull the Moon out of the background to make it clearer about how these maria straddle the centerline of the Moon:

They're a snap to remember. The north mare is Mare Frigoris - - the Sea of Cold. So, North - - North Pole - Cold, get it?
The second mare is smack dead-center in the middle of the Moon. It's called Mare Vaporum, the Sea of Vapors.

Now, I will tell you the incredibly stupid way I remember the name of this sea: "when you get a head COLD, you put Vicks Vapo-Rub on your chest." I came up with this memory aid when I was 8 years old, and it's been my personal shame to remember things like that for decades. Head Cold (up north where it's cold), then Vapo-Rub on the chest - - middle of the body, middle of the Moon. Sigh. Sad, but it's worked for me since the Apollo days.

Okay - - - remember where all the maria are:

"Five on the East Side,
Five on the West Side,
Two in the Middle
and an Ocean out West"

Let's press on to the West side of the Moon, okay?

Wow, that looks like a lot of maria, doesn't it? Fortunately, most of the dark part of the West side is taken up by the only named "ocean" on the Moon (the "Ocean out West") - - the Oceanus Procellarum, or the Ocean of Storms:

The way to remember the Ocean of Storms is to once again think of a US map - - the biggest ocean the United States bumps up against is the Pacific, which is in the Western part of the US. So, West... Ocean. And since it's the only "ocean" on the Moon, just remember that the name of the only ocean is the Ocean of Storms.

The Ocean of Storms accounts for almost half the "maria-type" surface of the West side of the Moon, so that brings the remaining maria in the West down to a more manageable number. Namely, there are only five more maria to remember. Let's look at the five remaining circles on the map of the Moon:
Okay, that looks like a lot of circles - - but you already know the blue one is the Ocean of Storms, so we just have to get the names of the five orange circles and we're done! Let's clear off the Moon and work on just the shapes:

So the first mare we'll deal with is the big round one at the top of the stack: Mare Imbrium, the Sea of Showers or the Sea of Rain.
There's an easy comparison you can make in your head - - the Ocean of Storms is HUGE. Mare Imbrium isn't as big as the Ocean of Storms, so it's just a "shower," not a "storm." Got it? Showers and Storms.

Okay, so the next mare on the stack is Mare Insularum -- the Sea of Islands.

Think of a rainy island, and you can remember that the islands are surrounded by the Ocean of Storms and the Sea of Showers. Another way to remember that it's a sea of islands is that there are some honking great craters scattered across it, like Copernicus and Kepler. We'll talk about craters next time, but right now just remember that the "islands" in the Sea of Islands are big craters.

This next mare is really difficult to remember, but I've kept it in my head with one of the stupidest metanymic memory aids ever conceived.

Mare Cognitum is the "Sea That Became Known" or The Known Sea. The way I remember this mare is that I *know* the mare below the Island Sea is the Known Sea. Yes, it's meta, but it works for me because I know the Known Sea is under the Island Sea. And now you know, too.

Here we go with the final two maria. As you can see from the places you've already learned, the places on the West side of the Moon seem to be concerned with weather - - storms, showers. The final maria are also about weather: namely, clouds and moisture. The mare on the bottom right is the Sea of Clouds, Mare Nubium.

The other mare is Mare Humorum, the Sea of Moisture.
How to remember these two? Well, on the Moon, "moisture is on the outside of clouds." Easy to see as the Sea of Moisture is closer to the edge of the Moon's horizon than the Sea of Clouds. Additionally, the Sea of Moisture is the lowest mare in the West - and so it's a drippy business, just like the Sea of Nectar, the lowest mare in the East.
Yes, the memory system is all quite infantile, but it seems to stick in the head if you give it enough time. Let's take a final look at where all these maria fit on the lunar surface:

Remember? The head COLD and the VAPO-RUB in the middle of the chest? Then, there's the only big Ocean, like the Pacific on Earth, that's way out to the West and is called the Ocean of Storms. 

Next there's the remaining five maria in the West - - the top one is Showers, which is like the big Ocean of Storms except Showers aren't as big as Storms. And it Showers on the Islands in the Sea of Islands, right in the middle of the West side of the Moon. And under the Island? Well, you KNOW that the Known Sea is under the Island, right? And you also know that the West is full of Clouds and Moisture - - but Moisture is on the OUTSIDE of Clouds on the Moon. Got it? Great!

Here's a look at what you know about the Moon:

"Five on the East Side,
Five on the West Side,
Two in the Middle
and an Ocean out West"

And you can name ALL of the maria now - pretty darned impressive! Next time, we'll go over some quick tips so you'll be able to point out ALL SIX Apollo lunar landing sites like a MOON BOSS. Failure is NOT an option. More soon.

Wednesday, November 9, 2011

You Will Be a Moon Expert in Five Minutes (well, half a Moon Expert)...

Thanks for coming back for the meat-and-potatoes part of the Moon talk. This episode, we'll get the map of the Moon memorized so that the next time you see the Moon in the night sky, you'll be able to impress your friends, family, and passers-by with your insanely-great knowledge of the Moon.

Here's the best part: you'll only have to learn HALF of the map of the Moon to be an expert. Why? You know this already: we on Earth only see one half of the Moon's surface. So, we'll only go over the NEAR side of the Moon. The FAR side - - the side we never see - - is mostly populated by hundreds of thousands of craters, like this:
And it's mostly a bunch of craters with really long Russian names (they were the first around the back of the Moon with a satellite, so hey -- naming rights!) so we'll just skip that part.

Okay, back to the Near side. When we look at the Near side of the Moon, we see mostly dark areas, punctuated by a couple of lighter, dusty cratered areas. Like this:

The dark areas are called by the Italian word for "sea," which is "Mare" (remember Galileo and his telescope? Hey -- naming rights!) The dark areas were given Italian names, and form the major identification structure of where things are on the Moon. It's sort of like talking about continents on Earth.

Now, it looks like there are a lot of mares on the Moon, and that might seem difficult to remember. However, if you break the Moon down into regions, it becomes super-easy to remember what is where on the map of the Moon.

First, a quick note about directions: when you're looking at the Moon in the Northern Hemisphere, north on the Moon is "up," south is "down," west is to the left, and east is to the right. So, let's think about it like this:

The secret to learn the map of the Moon is to learn this ditty about the Moon maria:

"Five on the East Side,
Five on the West Side,
Two in the Middle
and an Ocean out West"

Say it out loud. Don't worry - - nobody will notice. Say it:

"Five on the East Side,
Five on the West Side,
Two in the Middle
and an Ocean out West"

Okay, let's not learn the whole Moon at once - - we'll start with the East side of the Moon:

The East side of the Moon, the part that the New Moon first lights up at the start of the lunar month, has *five* major maria we can spot with the naked eye. Here's a bunch of circles to highlight the five maria:

Let's take the Moon away so we can focus on the maria circles:

So, there's one really circular mare on the upper right, three connected seas in the middle, and then a stretched-out one at the bottom. See the groupings? 1, then 3, then 1 more.

That one circle at the top right is the Sea of CRISES, or Mare Crisium.

See? You've learned the name of a lunar mare. Crises - - think of it as  NEW ENGLAND Crises, and it'll be easy to remember - -because it's waay up in the northeast part of the Moon, like New England is on a map of the United States. Crises - - you've got that one down pat now.
Let's get on with the clump of three. These are the "ITY" seas because their names all finish with "ity." Look:

There's the Sea of Serenity, the Sea of Tranquility (Neil! Buzz!), and the Sea of Fertility. Serenity, Tranquility, Fertility. How to remember this stuff? STUFF. Stuff - that's it! STF - Serenity, Tranquility, Fertility. Think of it as a sandwich - -the STUFF goes in the middle.

Last one on the East side of the Moon is the Sea of Nectar:

Nectar - - how to remember that? Nectar DRIPS down to the bottom, so the Sea of Nectar is at the bottom of the Moon's Eastern maria. The Sea of Nectar is also the oldest mare visible on the Moon, so it's going to be at the BOTTOM of the totem pole when it comes to stacking the maria on a timeline. 

Let's go over those East side maria again: Sea of Crises at the far northeast, then the STUFF in the middle (Serenity, Tranquility, Fertility), and then the dripping Sea of Nectar at the bottom. Done with half the Near side's maria!

We'll bring the map back in for a moment so that you can picture how it looks in the sky with the names (but of course you know these names now so you won't need a reference when you look at the Moon in the sky later, right?)

Isn't it something that you know all these names in your head now? I was going to continue with the west maria, but let's pause here for right now and pick up the west side of the Moon next time. You're doing really well sticking with this post all the way to the bottom! Come back again for the west side.

Saturday, November 5, 2011

The Shadow of the Earth

Everyone is an astronomer.

When we wake up in the morning, we look out the window and see if the Sun (the nearest star) is up yet. We talk about the days getting shorter as winter approaches, and we notice star formations like the Big Dipper when we're out walking in the evening.

It's human nature to be observers, and we notice a lot more than we sometimes realize. One of the things we notice in the sky is change, especially changes in position and shape. The Moon, of course, exhibits the most change each night we see her in the sky. Sometimes, she's a crescent shape, hanging low in the western sky after sunset. A few weeks later, the Moon is full, high in the sky near midnight.

Yes, you knew those locations (low in the west for a crescent Moon, high at night for a full Moon) even though you may not have thought of them before now. Again, it's all about observation. Mankind has looked at the Moon as long as there have been people on the planet. Four hundred years ago, Galileo Galilei turned one of his handmade, 30-power telescopes toward the Moon and drew this:

It's pretty much the same view I saw of the Moon last night:

Both Galileo and I saw the same phenomenon you've noticed with the Moon moving across the sky each night: the Moon has phases of light and dark, and the phases change over the month. 
Why does the Moon have a crescent shape sometimes, and is full other times? I thought this was a question with an obvious answer, and I thought everyone knew that answer. I was wrong about the latter bit. Last year, I took an Astronomy course whose first homework was to ask people to answer the question of why the Moon has phases. The answers were surprising, and to me, saddening.

The most common answer I received from the dozen people I asked "Why is the Moon a crescent shape sometimes and full other times?" was "Because the shadow of the Earth falls on the Moon differently each night." I was amazed. Wasn't the way the phases of the Moon worked taught in elementary schools since, like... ever?

I'm sure they've taught why the Moon has phases since at least 1904. I found a book about how to teach science topics from that year and they had a picture in the book on how to explain Moon phases: 

It's not difficult to understand. The *only* source of light in our Solar System is the Sun. Other stars are too far away to light things up, so every bit of light you see in the Solar System is either from the Sun, or light from the Sun bouncing off something else.

If you look at the nice graphic, half the Earth is in sunshine at any given moment, and half of the Earth is in darkness. It's the same for the Moon - - half of the Moon's surface is always lit by the Sun, and the other half is dark.

Now, since the Moon circles the Earth every 28 days or so, we on Earth get to see the sunlit parts and the dark parts every month. It's got NOTHING - zip, zilch, nada - to do with any shadow from the Earth falling on the Moon - - it's just that we look at the Moon from different angles as it's getting lit up by sunshine on half of its surface. 

The graphic also explains why we only see a new crescent Moon only just after sunset, and not in the middle of the night. The Earth is spinning counterclockwise in that graphic as we move around the Sun every year. If the Moon is in the position of a crescent between the new Moon and the 1st quarter Moon, we're only going to be able to see it just after sunset (about where the 'E' in Earth is if we're standing on the planet). By midnight, the Moon will have passed below the local horizon and we wouldn't be able to see it anymore. Conversely, a full Moon is best viewed in the middle of the night, when it's high in the sky over where it says "NIGHT" on the Earth graphic. If we saw a full Moon at sunset, we'd only see it *rising* in the East, directly opposite the Sun setting in the West. Imagine that you're standing at the "R" in Earth looking at the full Moon and you'll see what I mean.
Yes, the Moon sometimes falls into the shadow of the Earth - - we call that a lunar eclipse, but it only occurs one night every two years or so. It's not a Moon phase. 

Next time, we'll talk about the basics of the Map of the Moon. See ya then!

Thursday, November 3, 2011

Not a Teacher

On the list of the many jobs I'm incapable of doing, right after "Opera Singer" comes "Teacher." I'm an awful teacher - - I can't figure out how to assemble tests, I wander far from whatever syllabus is planned for the day, and I am miserable at grading papers.

If I were a teacher, though, I'd want to teach the geography of the Moon. Wait - let's not use "geography" as the proper word, because "geo" means "Earth." So, what I'd like to teach is the *MAP* of the Moon. Back in the dinosaur days when kids my age were studying everything they could about Project Apollo, Moon maps were everywhere: on the backs of cereal boxes, on placemats at Howard Johnson's Restaurants, in schoolbooks, and on TV. Everyone with a lick of interest in current events knew where the big craters were, and where Apollo XI landed.

All that's gone now. I was on the front lawn of my house last night, taking pictures of the Moon through my new Celestron telescope, and it struck me that I may be the only person for miles around who could name locations on the Moon. That thought made me really sad.

So, I've decided that I'm going to write three blog posts about the basics of the Moon: why it has phases, what the principal features are that we can see from Earth, and where and why the astronauts landed where they did.

I don't know if project will be interesting or not for my readers, but I feel like I must write about the topic to appease the part of me that wishes I could be a teacher.

Stay tuned.