Here we go...

Let's talk about the speed of light.

I'm serious.  I know this may seem remedial and basic, but our perception of the universe is entirely dependent on this seemingly simple concept.

(The following paragraph is paraphrased from our book, so if you read chapter 3, feel free to skip ahead)

It was in 1675 that the speed of light was first measured with some accuracy.  The scientist was Ole Roemer who, in an attempt to predict future eclipses of Jupiter's moons, determined that it took 22 minutes for light to travel across the diameter of the earth's orbit.  Roemer's approximation was a bit generous as we now know that it takes light 16.5 minutes to travel 2 AU.  Just to remind you, the distance between the earth and the sun is defined as 1 astronomical unit (AU).  The speed of light in a vacuum (c), as measured in 1983, is exactly 299,792,458 m/s.  We can say this value is exact because this constant is actually the number on which the meter is defined.  In terms of miles: light travels 186,282 miles/second.

We've all heard it: light speed is the cosmic speed limit.  Nothing can travel faster.  I think it's tough to put this idea into perspective because in day to day experience light seems to travel instantaneously.  There's no lag time when we turn on a light or when we talk on the phone.  Consequently, we regard the speed of light as infinite.  But in an astronomical sense, the speed of light is really kind of slow.  Let me show you.  It takes light 1.3 seconds to travel from earth to the moon, our closest celestial object.  Another rover, Curiosity, is scheduled to land on Mars less than seven months from now.  When it does arrive, communication to or from the machine will take 4 minutes.  Now at the edge of our solar system, it takes over 29 hours to receive data from Voyager 1.  The closest star (that we know about), Proxima Centauri is 25 trillion miles away and its light arrives here on earth in 4.2 years.  If these are our closest neighbors, you can understand why astronomers would want to define a more efficient unit of distance.  So the light year was born and it is defined as the distance that light travels in a year.  Got it?  It is not a measure of time.  Don't be fooled.

1 ly = 9,460,730,472,580.8 km ≈ 5,878,625,373,183.6 mi ≈ 63,241.1 AU ≈ 0.306601 pc

Clearly there is no shortage of ways to express large scale distances.  But no matter how I say 9,460,730,472,580.8 km, understanding a magnitude that large is simply beyond my grasp.

The entire field of astronomy is based on the fact that when we look at distance objects we are looking into the past.  Because light is not instantaneous, we can catch a glimpse of the beginning of the universe, we can watch galaxies form, and ultimately, begin to understand how we came to be.  The constant speed of light is the thing that allows us to examine our very existence.

This constant is just so cool.  I almost feel like I don't have the words to really do it justice.  But I'm going to try to make you care anyway.

So, light is an aspect of nature that dictates how we view the universe.  What are its ramifications?  Take a look:

• Red Shift 
• This important concept was studied by Edwin Hubble during the first half of the 20th century.  As he looked out at the universe (this happened to be on the 100" Hooker telescope) he noticed that many objects were shifted toward longer wavelengths thus appearing more red.  He determined that this redshift, as it was called, was due to the expansion of space itself and that galaxies are flying away from one another at an ever increasing rate.  Objects receding slowly, he discovered, had a small redshift and those with a larger redshift are not only more distant, but they are flying away at even higher rates.  Hubble suggested a rate of expansion now known as Hubble's constant.  By using (wait for it) the 200" Hale telescope, Allan Sandage was able to measure redshifts with considerable accuracy thus confirming his mentor's prediction.  We now know the universe to be some 13.7 billion years old.

• Light Horizon
• We have this gift of a constant speed of light.  There's a catch though; this same gift is also our ultimate limitation.  If the universe is 13.7 billions years old, that would imply that it would take that amount of time for the earliest light to reach us.  Right?  Well, due to the expansion of space, it is estimated the we can detect signals of light from anywhere within a radius of about 46 billions light years.  This is often referred to as our light horizon or the observable universe.  It is the sphere around us that is the absolute limit on how far we can see.  Does space end there?  Probably not, so any observer anywhere in the universe has his own light horizon.  

• Cosmic Microwave Background
• The most distant thing we can currently detect is remnant light from shortly after the big bang itself.  Called cosmic microwave background radiation, this light played a crucial role in determining a theory of an expanding universe.  Several missions have studied and cataloged this ancient radiation with interesting results.  This will be the topic of my next blog, so stay tuned.

• Biology 
• The value 'c' refers to speed of light in a vacuum, the vacuum part being key.  186,282 miles per second is actually too fast for our eyes to respond to light.  Conveniently enough, we know that light slows as it travels through things like glass or water.  This is because as it travels through these materials it gets absorbed and then re-radiates, causing a delay that slows the light to about 124,000 miles per second (still fast).  This is why a lens works; it can bend and concentrate large quantities of light.  It's incredible to think that our eyes have evolved to perfectly accommodate this quality of light.

• Interstellar Travel 
• Few ideas excite us like that of traveling through space-time.  Highly imaginative entertainment outlets have glamorized the adventure that would be extragalactic travel.  I think a lot of us hang on to the hope that perhaps one day the impossible will become a reality.  Even if it remains an impossibility forever, space travel is a fascinating thought experiment.  How would we do it?  Even light is too slow to travel any distance in a human time scale.  We've all heard of Einstein's famous equation, E = mc², right?  It basically says that as speed increases towards that of light, mass also increases to infinity.  Meaning, it would take an infinite amount of energy for an object with mass (like a spaceship) to travel anywhere near the speed of light.  And we know that to be impossible. But,what if we could exploit the very nature of space-time to aid us in our quest?  In other words, maybe we can cheat the cosmic speed limit.  Wormholes seem to be a favorite of scientists and non scientists alike.  By punching a hole into the very fabric of space-time, it's been suggested that we can travel to another place and/or time in the universe.  Of course manipulating a wormhole to a.) appear and b.) do as you like presents a whole other slew of problems.  I don't think we'll find ourselves traveling to some fantastic exoplanet via wormhole any time soon.  My favorite concept of interstellar travel involves a special kind of spaceship that would fold space to propel it to speeds beyond that of light.  Of course, all these concepts are speculation.  I wouldn't be surprised if there are scientists who have seen the end of their careers because of overzealous deliberation of these matters.  This doesn't mean this topic is void of real scientists.  You can check it out yourself here.

Anyways...

What about neutrinos?  You think those suckers were traveling faster than light?



Next time: The cosmic microwave background.  Stick around.

Who knew science could be so juicy?

I hadn't intended on posting more about Palomar Observatory. Really.  But it deserves one more shout out.  Today marks the anniversary of the day the 200" Hale telescope saw its first light.  I sort of mentioned it in my last post, but Palomar Observatory is historically significant because it is the thing that allowed astronomy to flourish in Southern California.

Thanks to the fantastic fundraising abilities of George Ellery Hale (a solar astronomer), the Mount Wilson Observatory was founded in 1904 with a grant from the Carnegie Institution of Washington.  There is a lot of information about Mt. Wilson and its 100" Hooker telescope.  I suggest you read about it.  Here's a link.  Unlike today's observatories, Mt. Wilson employed a whole host of its own astronomers, like Edwin Hubble, who made incredible contributions to astronomy.  This place was important, even Albert Einstein took a trek up that mountain to get a look at the serious science.  But here's why Palomar is so much cooler.

You may be aware of a longstanding rivalry between the Rockefellers and the Carnegies?  Well, if you were unaware, it's a real thing.  When Hale began to raise money for his pet project, the 200" telescope, he found the only group willing to fund his telescope was the International Education Board, who, oddly enough, was an organization of the Rockefeller foundation.  Not surprisingly, the International Board of Education was unwilling to award this new observatory to a Carnegie facility.  So Hale was promised $6 million to build the observatory and the telescope with one stipulation: the recipient would be the newly established California Institute of Technology and before they could have the money, they would need to secure an endowment to finance the observatory's operation costs.  Luckily, a wealthy banker agreed to do just that.

Without even trying, Caltech had accumulated its own observatory.  They didn't have astronomers, nor did they have a department or an optics lab.  But hey, at least they would have the world's largest telescope, right?  So began the tumultuous (and weird) marriage of Caltech and Mt. Wilson.  Mt. Wilson gave Caltech astronomers, Caltech shared its telescope and used that lovely endowment money to build a department and the optics lab that would be used to finish Palomar's 5.2 meter Pyrex mirror.

The end.

Okay, it's not the end.  But it's a whole lot of personalities and this blog is supposed to be about science.  Suffice it to say that that marriage has since dissolved, Caltech runs its own astronomy department and several telescopes, Mt. Wilson is still a cool place to visit, and the Carnegie Institution of Science is still around and thriving.

So back to it.
First light at Palomar occurred 63 years ago on January 26, 1949 when Edwin Powell Hubble pointed the 200" Hale telescope at NGC 2261.  Sadly, Hale did not live to see his dream realized.  His memory, though, lives through this telescope.  Like Hale always said, "make no small plans, dream no small dreams."

Technology continues to improve, but the infrastructure surrounding this mirror (and the mirror itself) is all original.  The spare gears built sixty some years ago are still hanging on the wall having never been used.  In fact, the observatory is so confident these spare gears won't be required that they built a brand new adaptive optics lab right in front of them.  That lab is now home to the world's premier adaptive optics system, the Palm 3000.
This truly is the perfect machine.

To 63 years, Palomar, and many more to come.


Not many institutions can claim sole ownership of such a spectacular facility. It is worth noting, however, that the Carnegie Institution is a partner on the Giant Magellan, a 24.5 meter telescope planned to be functional in 2018.  They've completed one of seven 8.4 m segments and finished casting the second.  Caltech and the University of California (hey, that's us!) have plans for a 30 meter telescope (along with partners Canada and Japan).  But alas, the Europeans are in the lead with their planned Extremely Large Telescope that would be 39.3 meters.  Wow.

My next post will be about science.
I promise.

You want to do what?!

People often ask me what I'm studying in school.  If I respond with physics or astronomy, the question that inevitably follows is, "What are you going to do with that?!"  Generally, the tone of complete and utter confusion tells me that people don't fully grasp the importance of physics, nor do they realize that people actually work as astronomers.  So, let's talk about what an astronomer is.


This is an astronomer:

Above is Fritz Zwicky.  He, along with Walter Baade, originated the term "supernova".  In the days of photographic plates, Zwicky found more than 100 supernovae.  Most notably (to me, at least), Zwicky was known for coining the term "spherical bastard", because no matter the angle you look at one, he's still a bastard.

Astronomy began to make great strides during the start of the 20th century.  With the construction of Mount Wilson Observatory in Pasadena, Palomar Observatory some 100 miles south, and the consequent birth of Caltech's astronomy department, many of the world's premier scientists were concentrated in southern California. As a result, several books have been written depicting the fascinating lives and careers of this generation's astronomers.  Two of my favorites include The Perfect Machine and Lonely Hearts of the Cosmos.  The former tells the tale of the construction of what was the world's largest telescope for nearly 50 years.  The latter chronicles the life of Allan Sandage, a careful observer and a graduate student of Edwin Hubble.  I admit that stories of the many characters of these institutions has certainly romanticized my view of astronomy.  While a few things have changed (women can now observe, and many telescopes are used remotely), these important facilities and people set the tone for observational astronomy that prevails today.


Running a telescope used to look kind of like this:

Here Edwin Hubble sits at prime focus of the 200" Hale telescope.  Before computers, each telescope required that someone follow a guide star as the telescope photographs other celestial objects.  Guiding was generally a job for a poor graduate student as prime focus can be extremely cold and uncomfortable.  

Modern day observing is quite pleasant.  Astronomers sit in a data room with heat, automated guiding (generally) and, most importantly, coffee.  The data room doesn't even have to be at the telescope.  The twin Kecks, for instance, can transmit data to computers at almost any partnering institution.  Which means real time data can be sent into a room right here on campus in Pierce Hall.

Not all telescopes require direct use of an astronomer.

Today, with remotely controlled telescopes, and automatic programming, a lot can be discovered with little assistance from an astronomer.  Take, for instance, the Palomar Transient Factory.  This fully automated, wide field sky survey utilizes several Caltech operated telescopes.  The main machine is the 48" Samuel Oschin telescope atop Palomar Mountain.  Weather permitting (which is about 300 nights a year) the telescope scans the sky in search of transient objects.  The whole northern sky is photographed every few days.   Data is sent to Berkeley where it is analyzed by an automated computer.  Should the program find an anomaly, it sends a command back down to Palomar where the 60" telescope will point to that swath of sky.  Once again the data is sent back up to Berkeley.  Should the peculiarity persist, a person gets woken up, and another astronomer (either on one of the Kecks or the Palomar 200" Hale telescope) gets their night interrupted while that telescope images that anomalous portion of the sky.  (It is my understanding that an astronomer is much more likely to get telescope time if he agrees to be interrupted by the PTF should it be necessary.)  In April 2010 a new supernova was discovered in just 29 minutes by this system.  It took Fritz Zwicky his entire career to discover his 120 (I think) supernovae.

Even with technological advancements, astronomy has always been (and will continue to be) an extraordinarily creative pursuit.  It's just the nature of science.  Astronomers seek to answer the questions that excite us all while simultaneously making us each a little woozy (please tell me I'm not the only one who gets light headed while pondering the mysteries of the cosmos).  Astronomers are the storytellers of the vast expanse that is our universe.  But their stories require data; lots and lots of data.  Not only is collecting good, usable data an important role of an astronomer, but an equally crucial ability is to effectively interpret that data.  For that reason, astronomers are observers, theoreticians, mathematicians, computer engineers, technicians, programmers, and dreamers.
They are also persistent.
And patient.
Because they wait for telescope time, and they wait for some poor student to slowly learn how to reduce their data.  And they're nice.  Astronomers are nice.
They pay close attention to detail.

In a nutshell:
In a quest for answers to the most fundamental questions of our existence, savvy astronomers collaborate with one another to stitch together a true picture of the cosmos.

Next time someone asks me what I would do with an astronomy degree, I'll tell them to visit this link.

Celestial Cheese

Choosing a name for this blog seemed to be an unnecessarily difficult task for me.  Given that the topic (astronomy, if that wasn't made clear by the title) is exactly what I'm trying to learn, picking a name that didn't make me look like a complete fool seemed tricky.  When racking my brain got me nowhere, I began to reference books and the interweb.

Hoping to find a good alliterative phrase, I first scanned a list of astronomy terms.  No luck.
Meanwhile, the phrase 'night vision' kept popping into my head.
No.  Absolutely not.

Next, I decided to marry astronomy with my one true love: cheese.  Naturally, I typed "astronomy cheese" into google.  This was almost as disappointing as my search for astronomical alliteration.  I did, however, discover that there is a wine, cheese, and astronomy festival in New Zealand every year.  I also found several terrible cartoons referencing our moon's very cheesy composition.  Oh, and I discovered a triple creme called Moon Dust Cheese.

See?

Note:  This is a Trader Joe's display.  I work for Trader Joe's and I assure you I never saw this cheese.  But, seriously, a triple creme cow's milk rolled in ash?  I would have eaten all of it.  Apparently, this cheese was available on the east coast stores during October.  Bummer.

Most importantly, in this pursuit of cheese and stars, I discovered proof of something I've always believed.  Astronomers have great senses of humor.  Check out this 2006 April Fool's Joke from the people at Astronomy Picture of the Day.

Anyways, back to the naming this blog:

I apparently settled on the name "First Light".  It's not terribly witty, but I think the concept of the first light collected by a telescope is a good parallel to the journey that begins here, with my first astronomy course.