Dear Alice
Recently a friend of mine told me that her friends from India insist that the moon in Seattle is bigger than the moon they see back home. Could this be true?
I’ve often wondered why the moon appears larger near the horizon and why I can’t capture that huge moon in a photograph but it has never occurred to me that the moon might appear larger or smaller from different places on the planet. What’s with that?
Thank you for any insight you might have.

-Terry

Terry,

In short, the Moon is always pretty much the same size, no matter where you’re looking from, and no matter where it is in the sky. All those differences are an illusion. I’ve been poking around though, and I can’t find anything about the “American Moon” vs “Indian Moon” illusion. I’ve got a number of resources on the Moon Illusion in general (why the Moon looks so big near the horizon) but only guesses about why it would happen more here than in India.

Moon Illusion

There are many books and papers written on the subject, but in short, no single theory really explains the Moon illusion. The popular explanations are these:

1. There are reference points for our brains near the horizon, but there are not reference points straight up. Hence we do a better job of judging the distance and size of the Moon when it is low – near mountains and trees.
2. Our brains flatten the sky. If you ask someone to judge how high something is in the sky they will always overestimate. This is why people often think the Sun is directly overhead, and if you’re up here near the same latitude as Seattle, the highest it will get is about 66 degrees. Therefore we think things above us are closer, and therefore they must be smaller. (I’ll bet this is related to our estimation of slopes – you know how you were telling your friend about that mountain you skied down that was at a 45 degree angle? Well, it wasn’t, it was much less of a slope than that.)
3. Relative size: this seems similar to #1, but it’s a little different. Because there is stuff next to the Moon when it is near the horizon it looks larger. When the Moon is high there is no stuff next to the Moon and we assume it is small.
4. There are also some ideas about how the eye perceives things.

None of these theories actually accounts for the illusion. The only for sure part is that the illusion is definitely all in your head – if you measure or photograph the Moon when it looks big and when it looks small you’ll see that the two measurements and pictures are pretty much identical.

Also, I’ve heard it told that if you see one of these large Moons, and you turn your head so you’re looking at it upside down, the illusion disappears. (Actually, what I heard is if you turn around, bend over, and look back through your legs the Moon will look normal, no illusion, because you’re looking upside down).

Indian Moon vs American Moon

I am absolutely positive that your friends are telling you exactly what they see. I also checked in with a couple of my husband’s coworkers who are originally from India, and visit home regularly. They agree that the Moon seems larger here, though they’ve never heard it talked about.

Here are my two thoughts:

Pollution

I don’t have good numbers to back this up, but of the over a billion people in India, tens of millions live in the big cities. Also, and here I’m really speculating, I would believe that of the people who visit or move to the US, a high percentage are from the cities.

The cities in India are notorious for their air pollution. That’s no good for looking at the sky. Also, if you’ve ever seen the Sun during a dust storm, or, more likely here in Seattle, through a haze of clouds (NEVER LOOK DIRECTLY AT THE SUN) you know you can see the disk of the Sun, and it looks smaller than you expected. The particles, be they dust, smoke, or water droplets, in the sky dim it down and take away the glamor of the Sun. It’s not as glowy, so it looks smaller.

How High the Moon

The latitude of India is between 5 degrees North and 30 degrees North. The latitude of the US is between 25 degrees North and 50 degrees north (yes, I’m ignoring Alaska, because that would just strengthen the argument). I give you those numbers to support for the idea that in India the Moon spends more time higher above the horizon than it does in the US. This would mean that we get the regular Moon Illusion for more of the Moon’s path through the sky (not just at Moonrise and Moonset) here in the US than you would in India. (Obviously the Moon can always be much lower, because it has to rise from the horizon, which is why I’m only looking at the highest part of the Moon’s path)

Here are some numbers to support that argument. If you don’t like numbers, skip this paragraph. Those latitudes means the highest the Moon gets in the US (in Florida) is two degrees past the zenith, and the lowest high (in Washington State) is about 15 degrees above the horizon. In India the lowest the Moon can get (when it is at it’s highest point in its path across the sky) is 30 degrees above the South horizon, and the highest it can be is all the way over to 72 degrees above the North horizon.

P.S. Moonwatch Week

Hey! I just noticed that it is Moonwatch week over in the UK. Heck, it’s the same Moon, so it might as well be Moonwatch week over here. So – this post is belatedly in honor of Moonwatching. Go out and look!

~ A l i c e !

Where’d I Get My Info

NASA’s Moon Illusion Page

The Moon Illusion

Griffith Observer I read a good article in a recent issue, but I can’t find the details right now.

Time and Date

Susan Sakimoto

I want to tell you about Susan Sakimoto. No, you haven’t heard of her. No, you won’t be asked to write a report on her (at least, probably not this year). She was the unofficial adviser for my Bachelor’s Honors thesis project in Astronomy-Geology at Whitman College. At the time she was working at NASA Goddard, now she’s a professor at Notre Dame. She studies lava flows … on Mars. And the part that really impresses me: she has kids (whose dad also works full-time at Notre Dame), she runs, and yet somehow her house is still cleaner than mine. Let me reiterate that:

Susan has:

• children (and it’s not like they have a stay-at-home-dad instead of a stay-at-home-mom)
• a full-time job – doing science (which you kinda never stop thinking about, and sometimes you have to work all night on to meet deadlines, and often sends you to meetings in who-knows-where)
• a regular “physical” hobby (not the kind of hobby you can put aside for a month and come back to)
• and then she took me on as an unofficial advisee…
• oh yeah, and her house is clean!

I dunno about you, but one or two of those sound like plenty to me. She’s one of those amazing people who does it all. I often feel like I can barely handle my full-time job and house chores. You start talking to me about kids and trying to make it to yoga every week, regularly, and I start wondering what I can drop or cut short.

I’m impressed, but these women are not rare. I’ve met many of them, and I continue to meet more. The key seems to be commitment. If you set your mind do something, and commit to it, you can. So go for it!

Ada Lovelace Day

So why am I telling you about Susan Sakimoto? Because today is Ada Lovelace day. Ada is widely attributed as the woman who wrote the first computer program. She worked closely with Charles Babbage on developing the first mechanical computers. She is one of the many amazing women in science and technology.

As part of the celebration of Ada Lovelace Day I signed a pledge saying I would write about a woman I admire, someone who works in technology. Unfortunately for me, there are so many women in science and technology I admire, that I didn’t know who to write about! There’s Ada herself, of course, and Annie Jump Cannon, Cecelia Payne-Gaposhkin, and Williamina Fleming. And then there are the current scientists (most of whom you’ve never heard of because you tend not to get famous until you’re dead or almost dead): Hannah Jang-Condell, Susan Sakimoto, Andrea Dobson, Pamela Gay (the list goes on and on and on). As you now know, I finally settled on Susan.

Carnival of Space

In the interest of clearing up loose ends – I owe you links to several Carnivals of Space:

• Carnival of Space #94 – Including the announcement that Bad Astronomer is giving away a Galileoscope!
• Carnival of Space #93 – Including a discussion about whether you’ll be able to visit ISS as a space tourist.
• Carnival of Space #92 – With bits about the crash of the Carbon Observatory …

Where’d I Get My Info:

http://findingada.com/

http://www.sdsc.edu/ScienceWomen/cannon.html

http://www.carleton.edu/departments/PHAS/Astro/pages/marga_michele/Cecilia_Payne.html

http://ocp.hul.harvard.edu/ww/people_fleming.html

http://womeninastronomy.blogspot.com/

Question: As you probably know, several of us from Pacific Science Center, went to a NASA Forum at the Museum of Flight on January 25, 2008. NASA officials talked about a very complicated plan for a manned-Mars mission sometime this century, using a permanent Moon base as a starting point. Have you heard anything more about this possible reality?

The Constellation Program

The program you’re asking about is called “Constellation” and the first goal is to put people back on the Moon by 2020. Indeed, the program is up and running and NASA is making progress as each day passes. The Constellation Program has three basic components. Let me look into the status of each.

The Orion Crew Vehicle:

Status: design and component mock-up

Currently NASA has a mock-up of the Launch Abort System being driven across the country to the White Sands test range. (Trust me, you want the launch abort system to work.). Actually, by the time you read this the LAS has probably already arrive at the facility for testing. NASA hopes to have finished testing and begin building by 2012.

The Ares Launch Vehicle:

Status: components built, in preliminary testing

As you can see from the picture here, the Ares 1 rocket fires just fine. Now the question becomes – is that firing under control? Is it exactly the thrust needed? Do the scientists and engineers have the control over it that they expected to have? NASA hopes to have finished testing and begin building by 2012.

The Altair Lunar Lander:

Status: design, rocket testing.

The Lunar Lander itself is mostly still on the drawing board, but NASA staff are testing out various rockets and modeling various designs.

Alice Enevoldsen

Where’d I Get My Info?

NASA’s Constellation Program

My website is going to go went black for Earth Hour – http://www.earthhour.org/home/

Join me!

Hi! Welcome to my new home … but bear with me, I’m still moving in.

P.S. If you’re new, and don’t know who I am or why I’m here, I run the Pacific Science Center’s planetarium in Seattle, WA. Come and visit, we’re the only planetarium in Washington that has regular public shows – and we’ve got shows EVERY DAY!

Do you need a Solar System? I’ve got one for you.

Bear with me, deep linking to the following website doesn’t work, so follow these quick instructions to acquire your own Solar System:

1. Go to Pacific Science Center’s website: http://www.pacificsciencecenter.org/
2. Click on “Store” in the middle of the right-hand column.
3. Click on “Gifts” in the left column.
4. Click on “Educational” in the middle pane.
5. You’re there! See “Solar System Cards” in that list? I made those. There are 44 awesome objects in our Solar System – plus several blanks and a list of suggested activities.

Funny Story:

So a few years ago, shortly after receiving my teaching certificate, Pluto was “demoted.” (In fact, my very first AstroInfo was about the new definition of planet!) Although people have many, many feelings about this, and there’s an ongoing argument, I’m going to ignore that part of the story for the time being.

What this created was a difficulty for teachers. Do we still teach Pluto? Does “My Very Eager Mother Just Served Us Nine Pizzas” become “My Very Eager Mother Just Served Us Nachos”? Does “Mary’s Violet Eyes Made John Stay Up Nights, Period” become “Mary’s Violet Eyes Made John Stay Up Nights”? What if Pluto is reinstated next year? What if you live in Illinois?

Well, the first question is easy. You most definitely still teach about Pluto. It’s not like the demotion made it evaporate out of our Solar System or disappear into nothingness. In fact, now it is probably more important to teach Pluto, since it’s the best-known representative of several whole classes of objects (Kuiper Belt Objects, Plutinos, Dwarf Planets, and Trans-Neptunian Objects). As we discover more and more of these, kids (and adults) need to know at least where these new discoveries are taking place. Teaching about Pluto helps with that.

But if it’s not a planet, what is it? What do I call it? What if they change the name? How can I teach science, if science is changing all the time? Those first two questions you can look up on the internet. The second two suggest some thought.

How can I teach science, if science is changing all the time?

This is a great question, and it applies to more than just “The Pluto Debate,” but that’s where I started. And it turns out, I wasn’t the only educator working on this problem. Anna Hurst from the Astronomical Society of the Pacific, and John Ericson at the Lawrence Hall of Science were also focusing on giving teachers a new way to teach the Solar System in the wake of The Pluto Kerfuffle. We were not in correspondence. We were not discussing this with each other, we did not meet and work on this problem together. In fact, I don’t think I met either of them until long after this.

Yet we all came up with the same solution: a set of cards or slips of paper, each with information about a different object in our Solar System.  Teaching the Solar System was going to have to evolve from “facts about each of the nine planets” to something that was more closely related to a lot of what planetologists actually do: classify, categorize, and identify. This mean that the new way of teaching the Solar System needed to involve dozens of objects, not just eight or nine, because there are actually dozens, hundreds, thousands of objects in our Solar System!

Besides the inherent flexibility and educational merit of this new activity, it also gives you a positive and fun way to teach about what happened to Pluto. You can allow your students to make their own definitions for planet, and see which objects fit (or don’t fit) their definition.

Anyway, I find it fascinating that the three of us came up with the same activity independently. I’m sure that many other teachers around the world also must have thought of this idea too, and so I claim no copyright or patent on the activity, but if you don’t have time to make your own set of 30-50 cards, you can (finally) just purchase a set from us – and support both my job and my planetarium while you’re at it!

If you’re interested in  John and Anna’s versions:

Lawrence Hall of Science Gread Explorations in Math and Science (since I can’t remember exactly which module has this activity, I’ll send you to the general link. If you know where it is, let me know!)

Astronomical Society of the Pacific’s The Universe in the Classroom, Issue #70 Hubble Observations of Pluto and Ceres. Scroll all the way down to “Activity 1: Sorting the Solar System” and the cards are there.

There is also a printable (draft) version of my cards, but I recommend ordering a nice set from above, since all the attributions for the photographs are correct, and multiple people have proofread them. The drafts will get you through the activity just fine, but the cards are a bit better.

You know how in sports they have playoffs with brackets where you predict which teams are going to win, and then of the teams that are left you make more predictions and so on until you have your prediction for the winner of everything?

I just spent half an hour on NASA’s “Mission Madness” predicting which Mission will “win” their “playoffs.” It was hilarious, and they made some of the decisions pretty hard.

Which do you think will win in a playoff between Hubble and Apollo 11?

Go make your own bracket predictions.

Short for now – more to be added later.

I saw Comet Lulin last night – FROM SEATTLE – through a break in the clouds. I observed for about 30-45 minutes, and did some hand-observations:

Here are some links if you want to learn more or see it yourself:

Video of it moving across the sky:
http://www.astrophotoinsight.com/node/1625

The most detailed picture I’ve seen so far:
http://bf-astro.com/cometLulin.htm

And the prettiest picture I’ve seen so far:
http://www.astropix.com/HTML/SHOW_DIG/094.HTM

A good article from this year with some background on its discovery 2
years ago:
http://www.universetoday.com/2009/01/14/comet-lulin-is-on-the-way/

A more recent article that mentions the new discovery about the
structure of the tail:
http://www.universetoday.com/2009/02/01/comet-c2007-n3-lulin-a-twist-in-the-tail/

Observation reports and charts:
http://www.skyandtelescope.com/observing/highlights/35992534.html

The 2009 March Starmap!

March is more-or-less here, and before I get to the upcoming constellations, I wanted to bring a few awesome stargazing opportunities to your attention!

This year is the International Year of Astronomy – and the 400th Anniversary of Galileo’s observations of Jupiter. Celebrate by doing some stargazing of your own. Here are just a few upcoming easy worldwide stargazing projects you can participate in!

March 16-28, 2009 – GLOBE at Night

Go outside any one of the above dates and take a look at Orion – no telescope or binoculars needed. GLOBE at Night wants to know how many stars you can see with just your eyes. But wait! They make it easy – you don’t have to count the stars – just compare what you see to diagrams, and pick the one that matches and submit your observations online. This data will be compiled into maps which will help astronomers track light pollution and how stargazing quality in various parts of the world.
Go to their webpage, download an observation packet, and take your family out to your backyard for some real science!
You’ll need to know your latitude and longitude:
Seattle is at: 47o37’N, 122o20’W

8:30pm Saturday, March 28, 2009 – Earth Hour

All you have to do for Earth Hour is turn off your lights – especially your outdoor lights for one hour at 8:30pm on March 28th. It’s that easy. And you might as well take that time to head outside and do your Orion observing for the GLOBE at Night project we just talked about! Earth Hour is about energy conservation and doing something about climate change – with the added benefit of supporting Dark Skies Awareness and making stargazing awesome even in big cities.
You can sign up and get more information, or just turn off your lights. Tell a friend; ask your neighborhood businesses to participate. Anything you do helps.

April 2-5, 2009 – 100 Hours of Astronomy

One of the cornerstone goals of the International Year of Astronomy is to get as many people in the world to look up at the sky, and to look through a telescope as possible. To work toward this this there’s going to be a 100-hour-long extravaganza of worldwide observing events. Here at Pacific Science Center we’ll be having our Earth Observation from Space month (all of April) where you can meet scientists and participate in hands-on activities on six designated research days.
Don’t have a telescope to do your own observing? No problem – join the 100 Hours of Astronomy team for a 24-hour webcast from research observatories around the world.
Be warned, when you visit their website – they write dates in the European style, so what we would call 04/01/2009, they’ll write as 01/04/2009! Shows you just how worldwide this project is!

And Now for the Constellations and Observables in the March-April Sky:

Notable Sky Objects

VENUS

I know, I said exactly this last month, but it’s still true! It may not be on my map, because the map is for later in the evening, but Venus is spectacular low in the southwest just after sunset. If you’ve got clear enough skies, poke your head out and learn why Venus has earned the moniker “the evening star.” (In June you’ll be able to poke your head out early in the morning and learn why Venus ALSO earned the moniker “the morning star.”) Venus will ONLY be visible for the month of March – by April it will be too close to the Sun from our point of view.

SATURN

Oh Saturn – with its rings tilted almost edge on to us, you really shouldn’t miss it. It’s beautiful, and with a little telescope you’ll at least be able to see its bright moon Titan, or the sliver of the rings running around the planet.

COMET LULIN

It’s not on my map because it’s moving too fast. Start by looking up some maps on Sky and Telescope, or somewhere like that, then gaze towards Saturn with a pair of binoculars. I know I’ve told you before that comets don’t streak across the sky – but this one is moving fast enough that you can notice the motion in just a short observation time. (It won’t look like it’s moving, but you’ll notice its position in relation to the background stars changes slightly over time). Once again, it won’t streak – if you see that it’s a meteor or an airplane. Moving a little slower? That’s a satellite. A dim smudge that doesn’t seem to move? That’s probably the comet, but don’t get it confused with M13, the Hercules Globular Cluster.

Watch for a full-serving AstroInfo on Comet Lulin coming up later this week!

New Constellations

BOÖTES – The Herdsman

SCIENCE: Arc to Arcturus, Speed on To Spica. This is how you find Boötes using the curve of the handle of the Big Dipper – and then that leads you on to Spica in Virgo!
Tau Boötes (sorta Boötes’ left foot) has an extrasolar planet! One of the so-called hot Jupiters. You can see this star just to the right of Arcturus – it’s the crook (corner) star off the little triangle that you’ll see there.
MYTH: The modern myth is that Boötes invented the plow, and therefore farming, and he’s the only “regular person” up in the sky – everyone else is a God, or partially Godlike, or something. I love this myth, because I can explain that Boötes is why we have cell phones and planetariums. It turns out that several different cultures depict Boötes as a herdsman or a farmer: the Saudi Arabians, the Egyptians (to whom the Herdsman is so important he also represents Osiris), the Greeks, and the Christians. Yowsa.

VIRGO – The Virgin (or “Princess”)

SCIENCE: Arc to Arcturus, Speed on To Spica. This is how you find Boötes using the curve of the handle of the Big Dipper – and then that leads you on to Spica in Virgo!
We are part of the Virgo Cluster of galaxies – and it’s called the Virgo Cluster because to see the rest of the galaxies in our group you look towards Virgo. There’s a bunch of beauties out there by Virgo’s face, so if you’ve got a scope, take a look, and if you don’t, look up some pretty pictures of our group of galaxies – most of them are over there.
MYTH: Worried about talking about virgins in mixed company? Well, princess is a perfectly acceptable way to talk about Virgo, also “girl” is good too. If your audience is up to it, you might mention that this virgin usually represents the Greek goddess of justice – so I wouldn’t try to cross her if I were you.

CORONA BOREALIS – The Northern Crown

SCIENCE: There’s not much too Corona Borealis, but it is a very noticeable grouping of stars, and therefore quite helpful in finding Hercules, especially in our murky Seattle skies.
MYTH: Obviously the Greek myth is about a crown, but the Housatonic Native Americans call this Ursa Major’s cave!

HERCULES – Hercules

SCIENCE: Do not miss M13 – the Hercules Globular Cluster! This is one of the oldest groups of stars in our galaxy – it’s like the old-folks home of stars.

MYTH: “Hercules is one of the oldest constellations, found in the cave drawings of primitive cultures. Not even the Greeks were sure of his origins. We are aware that very early cultures worshipped him, but who and what his starry figure stood for is a mystery.
“About 300 BC the Chaldeans said that this figure was standing victorious on the head of a twisting serpent. They associated these two figures, Hercules and Draco (the serpent) with their sun god, Ishdubar.
“The Chinese called Hercules ‘Titso’ or ‘the emperor’s seat’.” (From Zeta Strickland)

“Tiny” Guys

Going for the Gold? Here’s this month’s itty-bittys.

SERPENS – The Serpent

LYRA – The Lyre (just starting to peek up)

CORVUS – The Crow

CRATER – The Cup

COMA BERENICES – Berenice’s Hair

CANES VENATICI – The Hunting Dogs

LYNX – The Lynx

SEXTANS – The Sextant

HYDRA – The Sea Serpent (Big and dim, so big that it’s close to being biggest Northern Hemisphere constellation)

ANTILA – The Air Pump (Maybe you’ll see it, but it might be too far south)

MONOCEROS – The Unicorn

LACERTA – The Lizard

LEO MINOR – The Small Lion (Between the Big Dipper and Leo)

CAMELOPARDALIS– The Giraffe

Returning Constellations

LEO – The Lion
CANCER – The Crab
CANIS MAJOR – The Big Dog
ORION – The Hunter
TAURUS – The Bull
GEMINI – The Twins
CEPHEUS – King Cepheus
DRACO – The Dragon
URSA MAJOR – The Great Bear
URSA MINOR – The Little Bear
CASSIOPEIA – The Queen

Happy Sky Viewing!

Alice Enevoldsen

Where’d I Get My Info?

My memory, and Zeta Strickland

Don’t miss this week’s Carnival of Space – hosted again by Brian at Next Big Future!

There are mentions of the recent Texas Fireball (did it really actually hit?!), a discussion of the possibility of  liquid water on the legs of the Phoenix Lander, and Astroblog is rereading Galileo’s “bestseller” Starry Messenger and blogging about it as he goes through. So, get a taste for Galileo’s observations in his own words.

365 Days of Astronomy Calendar

I found this great Calendar on 365 Days of Astronomy’s Website – check it out for neat happenings in Astronomy.

Personal Note:

I had a major allergic reaction on Friday night, involving a trip to the Emergency Room. I’m fine. I have lived my entire life with extensive, severe food allergies, and it is just the way my life is. I know what to do, I carry an EpiPen. The only reason I mention this to you, is because there are some people in the world who don’t believe in the severity and danger of food allergies. I want you to know that you know someone with severe food allergies (me) – allergies that sometimes send her to the Emergency Room – so that you can continue (or learn) to be sympathetic to those around you who have these allergies.

This is my chosen non-astronomy cause. Just like Phil Plait fights the antivaxxers, I will confront the food allergy non-believers. You have been warned – this may come up from time to time on this blog, though I’ll try to keep it to a side issue.

For more information on food allergies, visit:

The Food Allergy and Anaphylaxis Network

National Institutes of Health – Medline Plus Medical Encyclopedia