The Starry Messenger

The universality of the sky was revealed to me last night.

It started simply enough. Dinner in the valley with my godparents, a typical Saturday evening in August. Given the size of the valley and the small social circles, it's common to run into several friends and families at any given event, and this time was no different. The couples at the table outside, the family at the table next to us and the one next to that, and the neighbors at the table in the far corner, all known to my godparents and after tonight known to me as well. But one of these introductions was to mean more than the others.

The house up the hill from my godparents belongs to a couple who open their home to most of the valley each year when they honor their patriarch. I have vague memories of attending these fetes as a young child and sporadic ones as an adolescent, which came flooding back to me as I was walking into the house for this year's celebration. This particular summer I had come to know two of the three now full grown children in the family so I was especially excited to attend. In between the cocktail chaos and the bustling buffet though, I never came across the third and eldest daughter and her husband...until Saturday night.

As I am introduced to the husband I find myself volunteered and volunteering to set up a telescope for the family, which the aforementioned patriarch has just purchased for their mountain house. I worry a little to myself that my academic qualifications may not translate directly into telescopic proficiency, but being an engineer in a former life and a tinkerer by birth, I can't wait to get my hands on the shiny new toy.

Late Sunday afternoon, I head up the hill to report for duty. Within an hour the hardware is assembled, but due to a lack of batteries, we cannot test the AutoStar function which is where all the fun is - once the telescope is calibrated to a location, it can automatically slew to any number of celestial targets. Instead, I am made an offer that I cannot refuse: drinks and dinner on the porch on a future and hopefully clear night in exchange for returning to help with the remaining set-up. I return home and immediately look up the weather forecast; it's my last week in the valley and I pray that there will be at least one clear night. Tuesday jumps out at me. I check multiple weather websites, and they corroborate the first - Tuesday looks perfect.

Tuesday morning I awake to blue skies and bright sunshine, just the kind of day that makes you never want to leave the valley. As I am going about the online portion of my day, a friend tells me to check out Google's home page - it's familiar logo is composed of telescopes in honor of Galileo Galilei. Unbeknownst to me, it is exactly 400 years to the day after Galileo first unveiled his telescope to Venetian lawmakers. His intention at the time may have been to sell the instrument to merchants for use at sea or in trade, but I have no doubt he had already turned his to the sky. Less than six months later, he would publish his first telescopic astronomical observations in a brief treatise he titled Sidereus Nuncius, or Starry Messenger.

Now across time and space, from a stone patio on the side of a mountain, I find myself looking at the very same sky that Galileo first explored, low those many years ago. The telescope has been calibrated and aligned and it is asking us to choose an object. The Milky Way brilliantly spills across the sky directly overhead with the Summer Triangle practically at the zenith. The Big Dipper is hiding behind the pine trees lining the driveway. An occasional shooting star flashes in and out of view. Unanimously, the dinner party demands a closer look at the exceptionally bright object rising in the southeast from behind the house: Jupiter. Upon acquiring its target, the telescope reveals the exact picture that Galileo once set his sights on. His discovery of four small satellites orbiting Jupiter was what prompted him to question to the principles of Aristotelian Cosmology that required the orbits of all heavenly bodies to be centered on the Earth.

The telescope we are using is not terribly more powerful than Galileo's original one. And the sky has only changed imperceptibly since his time. Standing there with my eye glued to the eyepiece and Jupiter and its four Galilean Moons sliding across my field of view, I feel a sense of connection to Galileo, the Earth, and the cosmos stronger than I've ever felt before. Contrary to many people's reaction to the vastness of space and time, I feel all the more special and privileged to be a part of something universal, in all senses of the word.

Astronomer for a Day...Er, Night

GLOBE at Night is an annual program put together by Global Learning and Observations to Benefit the Environment (GLOBE), which is a worldwide hands-on, school-based science education program. They encourage teachers and students to collaborate with active scientists to investigate their environment here on Earth.

GLOBE at Night is designed to study the spread of light pollution across the surface of our planet. Light pollution is the illumination of the night sky caused by artificial light sources here on earth such as streetlights, billboards, floodlights, stadium lights, etc. Quantifying it is important because it affects more than just astronomers. Cities and suburban areas are only going to continue to grow, and with them the amount of outdoor lighting. In addition to washing out the stars at night, light pollution can mess with both biological and ecological wildlife systems. More importantly it might even impact you, at least the ladies out there, as scientist recently reported finding a link between breast cancer and high amounts of light at night. The Washington Post published an article on this discovery last week and NPR's Bryant Park Project reported the news as well. This year of the program is an especially critical one as population and census data tell us that more than half the people on Earth are expected to be currently living in cities.

Now while this isn't becoming an environmental blog, I bring this to your attention because there is an astronomical connection here. As I mentioned, astronomers are not big fans of light pollution which is why most major telescopes are far away from big cities and towns and from most light sources altogether, often in deserts or on mountaintops or both. In fact, the Canary Islands of Spain have passed a lighting ordinance to preserve the visibility of the telescopes facilities located there. The University of Hawai'i has a great website dedicated to the importance of reducing light pollution. 

Your chance to help this effort comes any night between now and March 8th when you decide to participate in the GLOBE at Night program. You will be asked to observe and record the magnitude of visible stars where you live as a means of measuring the light pollution at your location. Using the constellation Orion, you will compare how bright it appears to you with example charts on the web to approximate the apparent magnitude of the stars where you are. (They will guide you through the steps, so don't worry if you the magnitude of stars means nothing to you). This will provide the data necessary to estimate your amount of light pollution. Then you can share your results online and compare the light pollution at your location with others around the world, like a global science project of sorts!

Just follow these five easy steps and you too can be an astronomer for a night!

Goodnight Moon

Tomorrow night the full moon will go into shadow...for approximately 50 minutes. From 10:01 p.m. to 10:51 p.m EST, the Moon will be fully eclipsed by the Earth when its orbit places it directly opposite the Sun in our skies.

The great thing about lunar eclipses, unlike solar eclipses, is that the Moon is completely harmless to stare at directly, with the naked eye or otherwise, because it "shines" due to reflected, and not direct, sunlight. In fact, I find I appreciate lunar eclipses best without any fancy equipment at all. The Moon moves fairly fast across the sky and the more you magnify it, the faster it will move out of your view. However you look at it though, it will be a beautiful sight to behold.

The alignment of the Earth between the Sun and the Moon is not a rare thing. However, the inclination of the Moon's orbit ensures that not every alignment produces an eclipse. While Earth essentially orbits the Sun in the plane of the ecliptic, the Moon orbits earth at an inclination of five degrees. This means that the Moon is only in the plane of the ecliptic twice for every completed orbit around the Earth. When you take this into account with the lunar cycle, lunar eclipses can occur approximately every six months. This doesn't mean that everyone should be seeing such a dramatic event this frequently. The conditions for a total lunar eclipse, like you can expect to see tomorrow night, require that the Moon passes through the Earth's umbral shadow. Yep, the Earth has more than one type of shadow; two to be precise, an umbra and a penumbra, as the diagram below illustrates.


Within the umbral shadow region, the Earth blocks all direct light from the Sun. In the penumbral shadow zone, the Earth's blocks most, but not all sunlight. When the Moon moves into the Earth's penumbra, only those with very keen eyes are likely to notice any dip in the moonlight. However, as the Moon passed into the umbra, the effects can be dramatic. The colors and brightnesses of the Moon can vary considerably both over the duration of an eclipse and from one eclipse to another, but most often the Moon transitions from it's normal steel gray to a vivid red or orange hue and then back again. While the Earth's shadow does indeed block all direct light from the Sun, indirectly sunlight still reaches the Moon after being refracted through Earth's atmosphere. As the light passes through our protective layers of gas and dust, the longer (redder) wavelengths are bent more. The less refracted shorter (bluer) wavelengths don't hit the Moon, but the red ones do, producing the brilliant color changes that we can observe. The dustier our atmosphere at the time of the eclipse the more sunlight is blocked completely, rather than just refracted, and the darker the eclipsed Moon appears during totality. 

The image at the start of this post is roughly what you can expect to see tomorrow night. If like me, you are in the Easter Time Zone of the U.S., the following graphic breaks it down for you. For those of you in other time zones, go here to get your customized version. My fellow North Americans best go out and catch this one as we won't get another show like this till the winter solstice in 2012.



(Image credits: Fred Espenak, NASA's GSFC, University of Nebraska - ClassAction)

Rudolph the Red Planet

Mars overload? Never.


The previous Mars posts were in reference the close pass between Earth and Mars which occurred on Monday night. However, orbital mechanics gives us something else to celebrate this holiday season. Earth, Mars, and the Sun will all align on Christmas Eve!

This particular configuration is called "opposition" as Mars will be directly opposite from the Sun with respect to Earth, or more simply Earth is directly between the Sun and Mars. For those of you who are uber keen, "conjunction" is the other time this alignment occurs, but with Mars on the far side of the Sun or the Sun directly between Earth and Mars. The diagram in Wednesday's post is actually more pertinent to this post as it illustrates the oppositions of Earth and Mars rather than their closest encounters. Jump back there for a look and then proceed on.

It's not easy to see in the diagram, but the elliptical orbits of the planets actually allow for their closest encounter and their opposition to occur separately. If all orbits were perfectly circular, the two events would be simultaneous and inseparable.

Let's step back a second, and discuss the geometry of the Solar System.

Each planet in the Solar System orbits the Sun in an elliptical orbit, as discovered by Johannes Kepler back in the day. As opposed to a circle, and ellipse has two 'centers' - termed foci - instead of one. For our Solar System, the elliptical orbits of the planets all have the Sun at one focus. But the orbit of each planet is elliptical in a different way; ellipses come in varying degrees of eccentricity, or distortion from circular. A circle is defined by an eccentricity of 0, while ellipses can have a range of eccentricities greater than 0 and less than 1. The more eccentric the orbit, the farther apart the two foci are. At an eccentricity of 1, the closed path of an ellipse breaks and becomes a parabola instead with the second focus at a distance of infinity. But that's a lesson for another day, back to Earth and Mars.

Earth's orbit is less eccentric than Mars' orbit, so the second focus of our elliptical path is closer to the Sun than the second focus for Mars. In the diagram this exaggerated to the point where Earth's orbit looks almost circular by comparison. This, combined with the oppositions plotted on the diagram, make it harder to see how the Earth can really be closer to Mars when the two aren't directly in line with the Sun, but this can be the case. Only once in much less than a blue moon will the two events occur at the same time. More often they will happen in succession as they do this year, with the closest encounter on Monday, December 18th and opposition on Monday, December 24th.

If you feel you are sinking into a geometrical quagmire, just take my work for it.

Whew, all that academic lead-up for what is hopefully still a worthwhile payoff...

The reason for this point being that in honor of this Christmas Eve spectacular, The New York Times ran an AP piece last week that proposed a cover version of "Rudolph the Red-Nosed Reindeer", with Mars as Santa's new best friend. Check out the lyrics in their entirety below and the full article here. Feel free to sing along!

Mars is a red-tinged planet
With a very shiny glow
And if you look to see it
You will find the moon in tow.

All of the other Yuletides
Santa would have at his side
The shiny nose of Rudolph
Acting as his big sleigh's guide

But this very Christmas Eve
Santa came to say:
''Rudolph, now with Mars so bright,
You can stay at home tonight.''

Then all the reindeer teased him.
And they shouted out with glee:
''Rudolph, the red-nosed reindeer
Outsourced to astronomy.''

Close Encounters of the Mars Kind

At 11:45pm tonight, Mars and Earth will be the closest they've been since October 2005. This planetary rendezvous is due to the elliptical orbits of both planets around the Sun and the point at which these two ellipses are nearest to each other. It happens once every two years for Mars and Earth and it's tonight!

So wrap yourself up in your warmest winter coat(s) and get your bum outside to check it out. No excuses for even you city dwellers as Mars easily outshines any urban light pollution (except for maybe in Times Square) and is well above the horizon. It can be best seen looking south in the middle of the night, moving westward till dawn. And with its red-orange color and steady glow, it is also larger than any star you're used to seeing in the sky - in fact, it is 1/100th the size of the full moon. That may not sound like much, but I assure you it's enough to grab your attention. For reference the full moon takes up half a degree of the sky and a typical star in the night sky is on average less than 1/1000th of the the full moon. So Mars is over 10 times bigger than the stars you are used to seeing! And to put it all in perspective, as many of you may know from seeing Apollo 13, the size of the full moon is comparable to the width of your thumb at arms length. You could say then that Mars is 1/100th the width of your thumb, but that's besides the point.

It's big, it's bright, it's red, and it's awesome.

(photo credits: NASA and the Hubble Space Telescope)