A Friendly Reminder: Spyside, the rock-duo featuring Ken Gardiner and Travis Searle (http://www.myspace.com/spysideband), appears this weekend on the television talent showcase “Community Auditions: Star of the Day” - http://www.communityauditions.com.

You have a few chances to watch, depending on where you are. For those not in the Boston/Providence/Portland area, we’re told that clips of individual performances will be available online at the Community Auditions website. (See URL above.)

FRIDAY MAY 16th -
9:30pm on TV38 WSBK Boston

SATURDAY MAY 17th -
10:30pm on WPXT The CW Portland, Maine
Midnight on WBZ-TV CBS Boston

SUNDAY MAY 18th -
Noon on TV38 WSBK Boston
7:30pm on NECN Boston Area

VOTE FOR US.
Voting is active from Friday after the episode premiers and lasts until airs to the following Friday morning, May 23rd. Votes count toward being included in the final episodes, where contestants compete for a car and a professionally produced record. **Everyone should vote as much as they can all week. Seriously. There’s no limit to how often or how many times you can vote, whether you saw the show or not.** Plus, voting is easy! You can do it in your spare time! Again, the website is:http://www.communityauditions.com/.

Feel free to pass this news on to any and all who might be interested. Thanks for the support!

–
TS/KG

Light Pollution (MP3, 17.2MB, 18:40)

Subscribe!

Hell, just email us and we’ll help you pick out a great star. You want something hot? Massive? With or without a companion? Would you like an accretion disk with that? Or some planets perhaps?

Go ahead, name a star. Just don’t pay for it.

Whatever the hell is Slacker Astronomy (MP3, 17MB, 18:30)

As always, we welcome your feedback so email us if anything comes to mind.

Our own Doug Welch wrote a very nice article in the latest issue of Sky and Telescope called “How to Hunt for Supernova Fossils in the Milky Way“. I can’t find a link to the article itself but S&T has a post about the article.

It’s really cool stuff — an accidental discovery of supernova light echos in the LMC has led to a new way to look for and study supernovae here in our own galaxy.

Doug discusses in detail how you can help hunt for these elusive light echoes. It would be a great multi-year project for a small college astronomy program or for accomplished astrophotographers with a bunch of really nice equipment.

Doug also describes in the article what happens if you find a light echo:

What happens if you find a candidate light echo? You become my new best friend!

How can you pass that up?!?

Your driving down the road in an automobile. You have an odometer in the car which tells you how far you’ve gone (x). You have a speedometer which tells you how fast you are going (v). When you punch the gas pedal or hit the brakes, your car accelerates (a), getting faster or slower. All of these quantities are related through calculus. Let’s say you start at x=0 and drive at v=40 miles per hour for t=15 minutes.

x = vt
x = (40mph*0.25 hours)=10 miles

We can write this as x/t = v. The velocity is the ratio of the change in position (x) to the change in time (t).

In math instead of saying “change in x” we say “delta-x” . In calculus we take this delta to be infinitely small and instead of saying “delta-x” we say “dee-x” (and write dx). So when I write dx I just mean a ridiculously small change in position. dt means an instantaneously small slice of time. The equation v=x/t can be written with this notation as v=dx/dt. This means the same thing as above, it’s the same definition of velocity, but we are implying these infinitely small deltas.

Another way of saying dx/dt is to say “the time derivative of x”. This just means “how x changes with time”. If we assume that we are talking about time we can use a shorthand which means “how x changes with time” and that shorthand is simply a single apostrophe like this: x’.

Now we can write our equation above like this:

v = x’

But your velocity can change over time, too. If you are going 40 mph and accelerate to 60 mph, your velocity changes as a function of time.

v = at

For some length of time (t) you accelerated at a rate (a) and your new velocity is your original velocity plus (a) times (t). If we rewrite:

a = v/t

and using our notion of infinitely small deltas:

a = dv/dt

we find that (a) has the same relationship to (v) that (v) had to (x) and thus

a = v’ = x”

So we have:

x The position
x’ The velocity
x” The acceleration

The velocity is referred to as the “first derivative of x” and the acceleration is referred to as the “second derivative of x”. These derivatives have a mathematical relationship that is beyond the scope of this article.

Now to differential equations. These are equations where we see complicated relationships between values and their derivatives. An example is a falling object (m) reaching terminal velocity due to wind resistance. The force on this object (F=ma) is the difference between the gravity (g) of Earth pulling it down (-mg) and the wind resistance (k) getting stronger as the object falls faster (kv):

ma = kv - mg

For simlicity we divide by m and just let k = k/m:

a = kv - g

and now use our fancy notation from above:

x” = kx’ - g

or equivalently:

v’ = kv - g

In this equation the change in velocity is a function of the velocity itself. So to know the acceleration you need to know the velocity but to know the velocity you need to know the acceleration!

This is the conundrum of differential equations. Finding functions that, when you find their derivative, give themselves back.

If you solve the equation v’ = kv - g the answer you get is the velocity as a function of time. If you plug in a very long time, the velocity reaches a limiting value — the terminal velocity.

You can’t really solve this problem without differential equations. It turns out there are many, many things in the real world, in physics, biology and engineering, that can be explained with differential equations. From orbits to population growth to thermodynamics, differential equations are actually quite useful.

Congratulations if you stuck with me! If you guys are interested we can talk a little about differential equations in astronomy next time.

Thank you!

We have a new show in the works.

Michael

So, cheers, my brethren. Please toast my absence with proper British ale. For you dear readers on the right side of the pond, think about heading up to Cambridge tomorrow!

M.

Check this sh!t out:

Credit: Brant Robertson, Spitzer Fellow, KICP/UChicago

This interview is quite long so we’ve uploaded low and high rez versions. The low rez version is the one in the RSS feeds.

If you subscribe to the feed, the audio is probably already on your box. Or you can check out the show notes or download the MP3 file directly:

Slacker Astronomy podcast interview with Brant Robertson (low rez) (MP3, 24.7MB, 1:11:20)

Slacker Astronomy podcast interview with Brant Robertson (high rez) (MP3, 65.6MB, 1:11:20)

Coupled together, these two items indicate that if there is an ocean beneath the frozen crust of the moon, then it’s reasonably warm, and rich in organic compounds. We don’t know how life started on Earth, but it’s a good guess that an ocean thick with organic compounds was involved at some point.

We don’t know how common life is and the possibility that life exists on Enceladus is quite small. Still, research in the solar system and in the deep oceans of Earth are suggesting some exciting new possibilities for environments suitable for life.

There’s more info from NASA and the AAVSO High Energy Network.

This is a great slacker project. It doesn’t take much time or any tools. You can do it with kids, friends, or whoever. If you forget to do it tonight, you can do it tomorrow or the next time you have clear or mostly clear skies. You have until March 8, 2008 - next Saturday. This is a worldwide project.

To participate, go to the web site and check out the limiting magnitude charts to know roughly what the differences are in what you can see. Then go outside and block the most glaring lights. Let your eyes adjust to the dark for a few minutes as you locate Orion. Carefully consider what details you see in the constellation. Only Betelgeuse - the red shoulder star? All three belt stars? Stars close below the belt? The feet and shoulders? The head cluster? The Orion nebula? Fainter stars below the lower shoulder? Remember the faintest stars you could see.

By the way, Mars is the “extra star” somewhat nearby rivaling Betelgeuse with its bright red color.

Then go inside and report your observation. You’ll need to know where you are, what time you made your observation, and which chart most closely matches what you saw. In 2007, there were 8,491 observations. After a week of observations this year, it looks like there are fewer than 2000 observations.

I’ve always wanted to take a shot of the moon during a total eclipse because it is the only time you can get stars in the background. Usually the moon is so bright that it drowns out all the stars. So I snapped a few photos tonight with my wife’s digital SLR. It didn’t have as much zoom as I wanted but I still got a bit of the effect I was hoping for. Make sure you click the image to see the large size. I’m looking forward to looking at all the other images that are popping up around the net.

The eclipse was very nice here in Minneapolis although it was cold  at around -2F (-19C). Did you get a change to take a look?

And then get out and experience the eclipse tomorrow!

Tom was a unique character and TASS was a project I got involved in early in my amateur astronomy days. He was recently awarded an honorary lifetime membership to the AAVSO, something that made him very happy. I had sent this to him when he told us about it on the TASS list:

Tom, I want to add my congratulations. TASS was the thing that accelerated my interest in variable stars. The AAVSO was there, too, but it was working on new TASS variables that really lit the fire under me. I’ve enjoyed your philosophy, as well, that the errors, mistakes and misfires should be just as public as the successes. It is too bad more researchers don’t share that view.

Thanks for the data, Tom. I know you enjoyed yourself and that is all that matters.

Check out CASSIE (Cassini at Saturn Interactive Explorer). It uses some weird plugin but once installed you can zoom around the Cassini timeline and watch the view from the spacecraft.

(Thanks Ben!)

Via Cosmic Log:

Ten years after supernovae provided the first evidence that the expansion of the universe is accelerating, a survey of more than 10,000 galaxies has provided independent confirmation that the cosmic speed-up factor known as dark energy is for real.

Cosmic Log provides a very nice analysis of this press release from the European Organisation for Astronomical Research (ESO).

So it seems that the expansion of the universe is indeed accelerating. This means that cosmological constant is non-zero and dark energy, or some alternate explanation, is necessary to explain the observations. Our cosmology seems to be consistent and correct in terms of what is happening, we just don’t know why it is happening.

In this case it looks like they got lucky and were able to catch RS Oph, a recurrent nova, in outburst. The surprise was — the dust:

The nuller saw no dust in the bright zone, presumably because the nova’s blast wave vaporized dust particles. But farther from the white dwarf, at distances starting around 20 times the Earth-sun distance, the nuller recorded the spectral chemical signature of silicate dust. The blast wave had not yet reached this zone, so the dust must have pre-dated the explosion.

“This flies in the face of what we expected. Astronomers had previously thought that nova explosions actually create dust,” said Richard Barry of Goddard, lead author of the paper on the observations that will appear in the Astrophysical Journal.

The team thinks the dust is created as the white dwarf plows through the red giant’s wind, creating a pinwheel pattern of higher-density regions that is reminiscent of galaxy spiral arms.

Novae have been studied for a long time and we thought we had them pretty much figured out. If confirmed, this result could trigger a lot of activity in the variable star community.

This was the Messenger spacecraft’s first of three 200km high fly-bys of Mercury. The next will be October 6, 2008, and the third will be September 29, 2009. Each fly-by slows the spacecraft as it heads to orbiting Mercury in March 2011.

Kevin B. Marvel, Executive Officer

The AAS is now making the invited and prize lectures at each AAS meeting available online for those who could not attend the meeting, but would still like to benefit from the invited and prize talks.

Audio and video versions are available at:
http://aas211.showmaestro.com/

The talks will be indexed on iTunes (under podcasts) by mid-March and also available on the AAS webpage.

These are very interesting talks by notable professional astronomers. At least one of the talks is aimed at the general public but almost all of them will be interesting to amateur astronomers in some way.

Thank you AAS! Nice to see you are “getting it” when it comes to making your content widely available on the Internet.

The BBC is reporting on an announcement from last week’s AAS meeting:

A giant cloud of hydrogen gas is racing towards a collision with the Milky Way, astronomers have announced.

Smith’s Cloud, as it is known, may set off spectacular fireworks when it smacks into our galaxy in 20-40 million years.

30 million years is tomorrow in astronomical terms. This interaction is taking place as we speak. These kinds of collisions, like our eventual collision with the Andromeda Galaxy, will keep our galaxy interesting for a very long time. In fact, it’s possible that our very existence is a result of a wave of star formation from such a collision.

So getting knocked around a bit is actually a good thing if you are a galaxy.

Our friends Pamela Gay and Fraser Cain from Astronomy Cast, along with astronomer/sex symbol/author Phil “The Bad Astronomer” Plait have all the latest from this week’s meeting of the American Astronomical Society.

My personal favorite of their reports: Hubble Sees a Double Einstein Ring

Slackerpedia Galactica 8.0: A Brief History of the Universe (MP3, 17.2MB, 36:12)

In this show Doug and I discuss the the cosmological timeline as I wrote about in a previous post. We also talk a little about asteroid 2007 WD5 and its possible upcoming impact with Mars.

Are you on facebook? If so, you can add a new, highly-useless application which lets you view a random Slackerpedia Galactica article in facebook.

I wrote this just to test out facebook’s developer API, and it has been a fun little project. There is some really funny stuff in Slackerpedia Galactica and I’m glad we can share it easily with the facebook community.

So check out Slackerpedia Galactica on facebook!

In this case, a level 4 advisory would be issued at this time for asteroid 2007 WD5. Current calculations indicate a 1-in-75 chance that the asteroid will impact Mars around 10:55 UT on 30 January 2008 (all times Earth-based).

Earth scientists blame light from Earth’s Moon for impeding their observations of 2007 WD5. By early January 2008, they hope to have additional observations that will further refine the asteroid’s path. If Earth had an observatory on the far side of the Moon, maybe these calculations would take place in a more timely manner.

2007 WD5 passed by Earth in early November 2007 and was discovered on 20 November 2007 by the Catalina Sky Survey. It is estimated to be about 50 meters across.

Although the center of the asteroid’s predicted path appears to miss Mars by 50,000 km, that path’s uncertainty region is large enough to graze the planet. In comparison, 2007 WD5 missed Earth by 7.5 million km.

Earth scientists believe that the over-achieving Earth spacecraft that are on Mars are not in danger. MER Opportunity is near, but not in, the possible impact zone.

For further details, pictures, orbital animations, and updates refer to the NASA JPL’s Near Earth Object Program including this report on 21 December 2007.

In the beginning t equaled zero seconds (t=0). A Big Bang-like thing happened and the universe began expanding. It was very hot and very dense cold and empty^[1]. The universe expanded exponentially in a period known as inflation. Inflation ended around t=0.000000000000000000000000000000001 seconds.The universe was so hot that everything was relativistic and “radiation like”, so the universe was considered radiation-dominated.

At around t=1s neutrinos decoupled, meaning they stopped interacting with matter or radiation and just continued on their way forever. This is the elusive CNB — the cosmic neutrino background. Around the same time the ratio of protons to neutrons “froze out”.

At around t=200 seconds the temperature had dropped enough that deuterium could start to form. These were the first nuclei in the universe. This is the beginning of the era known as Big Bang Nucleosynthesis (or BBN). After less than 15 minutes, BBN ceased and the initial ratio of helium to hydrogen was established. The universe was now about 20 minutes old and for the next 50,000 years it was a hot bath of radiation and light elements that continued to expand and cool.

At t=50,000 years or so, the temperature got low enough that matter started to dominate the universe and by t=350,000 years the universe was entirely transparent to radiation, giving rise to the “last scattering surface” which we see as the CMB (cosmic microwave background).

By t=250,000,000 years or so, stars and galaxies had formed. The universe continued to expand and cool even as the the universe evolved to what we see today.

At about t=10,000,000,000 years, about 75% of the present age of the universe, matter ceased to dominate the universe and Λ (lambda) know as the ominous “Dark Energy” began to take over. Thus, the universe is not just expanding, it’s expansion is accelerating.

Currently t=13.7 billion years and the energy density of the universe is comprised of roughly 0.00008% radiation, 30% matter and 70% Λ, the temperature is T=2.7 degrees Kelvin and the Hubble rate, which is a measure of the expansion of the universe, is H=70 km/s per megaparsec.

^[1] My cosmology professor was kind enough to read my post and to this point he said “The universe wasn’t hot during inflation. It was actually cold and empty; the inflaton field was a condensate, totally different from a thermal bath; the best analogy is a Bose-Einstein condensate at T = 0. The condensate at the time t =0.000000….1 you say decayed. The decay products then thermalized to very high temperature.”

First Principles 4.0 - Inside Stars (MP3 file, 26.7MB, 28:24)

Black holes are the most likely source of the mysterious ultra high-energy cosmic rays that bombard the planet… Observations at the world’s largest cosmic ray detector suggest the particles are emitted by huge black holes in the middle of nearby galaxies. 

Cosmic rays are a pain in the ass for spectroscopy, astrophotography and other CCD-based astronomy. Especially spectroscopy is plagued by cosmic rays. There are 3 kinds of cosmic rays that I’m aware of, electrons, protons and Helium nuclei (or alpha particles). The cosmic rays discussed in this article are high-energy and create a shower of interactions when they slam into the earth’s atmosphere.Pretty cool that we are starting to see results out of the Pierre Auger Observatory.

Comet Holmes…was no brighter than magnitude 17 in mid-October…But the comet’s brightness has suddenly rocketed all the way up to 3rd-magnitude, brightening nearly 400,000-times in less than 24-hours!

Go try see it.

Lord knows we need more logic in this world!

This is only my second primary authored paper in a major astronomy journal. My others have all been in smaller journals. Many were refereed journals of good quality, but they tend to be limited in scope and/or size. PASP is a general astronomy journal. But even it has some areas where it is more known, two examples of which are astronomical equipment and variable stars. My paper, naturally, involves the latter.

SS Cyg is one of the most popular variable stars. It’s a binary system where a white dwarf is pulling material from a smaller, red dwarf companion. The material builds up in an accretion disc and leads to an eventual outburst, where the star grows in brightness by around 4 magnitudes or so. It’s fun to watch SS Cyg in a backyard telescope. Day after day it is faint, then one day BOOM, it’s one of the brightest stars in the field.

The best part is that we don’t know exactly why this occurs nor can we predict it with better than ~20% accuracy.

In 2005, I suckered invited some amateur observers to observe SS Cyg as much as possible, all night long, for four months. They observed many hours per night, in V and Ic (near infrared) filters. The idea was to look for any kind of activity that could be a precursor to an outburst.

The four months stretched into two years thanks to the dedication of this team (who are all coauthors on the paper). Thousands of observing hours were spent on this star. I don’t know of any star that has had this much coverage (other than our Sun of course). The amount of data broke our web server half way through the campaign! And it took me 4 weeks of 40-hour/week work just to clean the data and get it into a state to be analyzed.

The paper was written as part of an independent study class with a professor in the physics department at Tufts. A draft was done in May, polished over the summer and submitted in mid June. The referee returned comments about a week after submission. It took me about two weeks to respond to the comments and resubmit. After that, another week for notification of official acceptance and assignment of a publication date.

The result? We didn’t find a precursor. But we learned a ton and were able to place lots of limits. The referee said it would be an “important contribution” to SS Cyg. Lots of science (most?) is null results. But the null results lead to the positive results. We did find one significant result in the paper, though. There is a correlation between intervals between outbursts and a long (>1000 day) period in the long-term light curve of SS Cyg.

We are planning to apply for a grant to expand this project for three years. The goal will be to constrain the models even more with better and more precise coverage.

This will probably be my last primary-authored astronomy research paper in many years as I shift focus to education and psychology research. I have one more paper that is pending my corrections to a referee report, but I don’t know if that will happen given my time constraints. And I have one more idea in my head that I really want to do, because it would be fun and neat. But, again, time probably won’t let it happen. I have my first field study in the social sciences planned for this January at the Adler Planetarium in Chicago. After that, I’ll need to analyze and publish THAT data. Dealing with human subject data is a completely different world than data from the natural sciences. Even the statistical methods are different.

Onward… and upward?

Nothing could be further from the truth. Cosmology is a physical science and it is a rigorous science. While there are certainly mysteries and unknowns, cosmology is on a very firm basis and really doesn’t resemble philosophy in the slightest.

If you are interested, our textbook is very readable and was recommended to me previously by another cosmology researcher. It’s Introduction to Cosmology by Barbara Ryden. Dr. Ryden does a very nice job of laying out the context in the early chapters and then delving into the details of physical cosmology in the later parts of the book.

Today in class we talked about the evolution of the universe in 3 main eras — the radiation dominated early universe, the long matter dominated universe, when galaxies formed and the present era where the universe is dominated by “dark energy” (known to cosmologists as Λ). The radiation dominated era was quite brief, lasting only about 50,000 years. The matter dominated era was about 9 billion years long and Λ has dominated for about the last 4 or 5 billion years or so.

We know this.

Now, we can watch the International Space Station (ISS) and a wide variety of artificial satellites fly by. I’ve taken pictures of the ISS and Space Shuttle flying side-by-side. To me, it’s awesome that there are people living up there in space.

The Space Station is easy to spot when you know when to look and have good skies. Even a slacker can do it. It doesn’t zip by. You usually have enough time to find it moving slowly and steadily like a plane without flashing lights. It’s usually rather bright (around magnitude -1 to 1). Its shine is reflection of sunlight because it’s getting sun while you are in the dark. Sometimes you’ll see it big and bright and then “poof!” — it slips into the Earth’s shadow.

Visit Heavens-Above (http://www.heavens-above.com/) and find your location. Then under Satellites, click on 10-day predictions for ISS. If there are any passes over your location, you’ll get a table listing them. Realize that the times are in 24-hour time, so 5:47 will be 5:47am (too early for many slackers). A time like 19:54 is 7:54pm. Much better for slackers. Click on the date to get a map showing where to look. It’s easiest to see the passes that have a maximum altitude (center column) of 50-90 degrees but even the 15 degree high passes are readily visible.

In these crisp days of fall and spring, it’s fun to observe the skies above us with our own eyes rather than through a computer screen. Check it out.

In 1998 observations of Type Ia supernovae suggested that the expansion of the universe is speeding up. In the past few years, these observations have been corroborated by several independent sources: the cosmic microwave background, gravitational lensing, age of the universe and large scale structure, as well as improved measurements of the supernovae.

When Einstein developed general relativity, as is well known, he added a factor to his equation because it was necessary to reproduce the universe he thought we lived in — a static universe with no expansion or contraction. When we observed that the universe was not only expanding but accelerating in its expansion, that extra term in the equation was already there to express it.

That term is capital lambda (Λ). It’s a pressure term, in one way of thinking. Just like a gas or a fluid has pressure, it appears the universe has some sort of pressure. In another way of thinking, Λ is an energy because pressure and energy density are related in a linear way. So there is an apparently uncompensated energy that results in a universe that is out of balance — it’s being very slowly blown apart.

So, like dark matter, dark energy is “real”, in this case “real” meaning that it’s a name for something that we really do observe. Some people are uncomfortable with this. They think, in the example of dark energy, that we don’t need an extra term in the equation, the rest of the equation is somehow wrong. That is, of course, another perfectly valid option. Either physics is wrong or dark matter/energy exist or both!

But don’t be fooled — the phenomena are real. We really do so find an unaccounted for gravitational influence (dark matter) and we really do see something acting like a pressure in our cosmology (dark energy). This is not philosophy, it’s science and it’s very good science at that. The fact that there are still things we don’t know is the fun part!

The thought I had was — would ancient people have been able to figure out that artificial satellites are artificial? That they are the products of design and not a part of the natural world? With the whole faux debate about evolution vs. intelligent design, the question arises: would scientists recognize design if they found it? Could Kepler have figured out that an artificial satellite was artificial?

I believe the answer is yes. In one sense, an artificial satellite behaves exactly like a natural satellite. But not quite. The geometry of a man made object is more perfect. I believe one could map the brightness changes, just like we do with asteroids, and come up with a good model of the shape of the object. It would take time and precise observations, but the non-natural nature would eventually become apparent.

So to the rescue are Michael, Doug and Travis. They will keep things running and add some new ideas of their own. I’ll try to contribute where I can, in between weekend benders of coffee and red bull.

Rebekah is still here, but she has been in another state most of the summer experiencing a fabulous surge in her professional acting/singing/dancing career. She even has achieved qualification for the much sought after actor’s equity card. Congrats to her!

Here is a glimpse into some of the stuff I’m doing at Tufts. The symposium is next week and I’ll post a report. Astronomy education research is a relatively immature field with lots of varying interests and philosophies.

We are going to decommission this discussion area. We are doing it for a few reasons. One, there just isn’t that much activity here and we don’t really use it for much on an official basis. Two, we’d like to start opening up comments on the blog posts. People are very used to that form of interaction. Three, we’d like you to consider writing an occasional blog post for the blog! If you register and ask us, we’ll promote you to a Contributor. You can write blog posts and if we like ‘em, we’ll put them on the blog.

There are tons of great astronomy discussion forums on the web, such as the Bad Astronomy and Universe Today Forum. Feel free to suggest others in the comments. We’d like to bring discussion here at Slacker Astronomy back into the blog, so please don’t be afraid to get discussions going in the comments of blog posts.

What makes this site such a good watch, or listen, or read, is that as well as being jokey and enthusiastic, there is a real depth of knowledge.

Thanks, Kate!

A while back I wrote a post about energy.

Here’s another example of energy that I think is interesting. When you take an automobile which is initially at rest and get it going 55 miles per hour, it gains kinetic energy. KE = (1/2)mv^2. So a car that weighs 2000 lbs. (900 kg) going 55 mpg (25 m/s) would have KE=(1/2)(900)(625)=280 kJ (kilo-joules) of energy. That energy comes at the expense of gasoline — chemical energy — exactly 281 kJ’s worth. Excluding all the messiness of friction and air resistance and such, we used exactly the same amount of chemical energy as we gained in kinetic energy. So it doesn’t matter if you use gasoline, hydrogren, electricity or biodiesel, it takes 281 kJ of energy to get your car going 55 mph.

Now you see a stop sign and you hit the brakes. You take all of that kinetic energy and put it into heat, given off by your brakes. The energy went from the gas into your car’s kinetic energy and then the friction from your brakes heated up the air. What some hybrids do, which is really cool, is instead of putting that energy into heating up the air, they put it back into the car. In some cases they literally spin up a big, heavy gyroscope. So they put the kinetic energy of the car into kinetic energy of a big spinning thing. Then when you hit the accelerator, it puts that energy back into the drive shaft and you accelerate back up to 55 mph without starting from zero energy. Cars that do this get “free” energy compared to cars that don’t. When we accelerate and brake, back and forth, all day long in our cars, we are throwing away ridiculous amounts of energy.

If you were flying in space instead, once you got going 55 mph you could turn off that gas and you’d keep going 55 mph forever (or until some force started messing with you). The reason you can’t do this on earth is because all sort of things steal the energy. The heat from your engine, friction in the moving parts, air resistance — they all steal energy that you have to keep putting back with your engine.

So one of the challenges facing us with our on-going “energy crisis” is figuring out how not to turn energy into a form that is not usable to us. The classical example is heat, like the brakes on our car. Anything that gives off heat is wasting energy. Your laptop wastes tons of energy in heat. If they could make CPU’s that didn’t heat up, your battery would last for days.

There is no shortage of energy on earth. The Sun rains down something like 1 kilowatt per square meter. There is tons of kinetic energy in the wind and ocean. We like to burn things like coal and oil –they are ridiculously finite compared to the Sun, the wind and the ocean. Renewable energy isn’t just a good idea, it’s the only long term option.

The BBC reports: Dark matter clues in oldest stars:

“In cold dark matter the particles move very slowly; in warm dark matter they move very quickly,” he explained.

“We found that if the dark matter consists of these fast moving particles, then the first stars form in very long, thin filaments…Some of the stars that formed within the filaments would have had a relatively low mass, which is of interest to astronomers as they have a long lifespan and could still survive today.

Dr Theuns added: “In stark contrast, what happens in (the simulation with) cold dark matter is very, very different. Here, the first stars formed in little lumps of dark matter, and just one star per dark matter lump. And these stars are probably very massive as well: 100 solar masses. Because these stars are so massive, they die very quickly; so you wouldn’t find such stars in the Milky Way today,” he said.

Everything I’ve read about the “1st stars” (or Population III stars) is that they would have been very massive because they lack metals (elements heavier than Helium). The stars that followed them (Pop. II and Pop. I) had access to heavier elements created by the supernovae of the Pop. III stars and evolved differently as a result.

What’s important here, as I read it, is that we have a “1st stars” option which creates low-mass stars that could still exist today. So finding such stars could tell us something about dark matter.

Listen now (MP3, 48:06, 33.2 MB)

The show notes are on the Slackerpedia Galactica.

And really, in all seriousness, we truly do have a new show almost all set to go!

(Travis? Travis, can you hear me?)

Don’t forget to watch Seeing in the Dark on PBS on September 19th, 2007. If you missed it, get it on DVD, hopefully in HD.

I was lucky enough to be part of this, so I am biased, but I think it is very well done. The photography is beautiful, the music (by Mark Knopfler) excellent and the subject matter really quite interesting, even, I’ve seen, to people who don’t know anything about astronomy.
More into at http://www.seeinginthedark.org/

http://www.lolife.com/astronomy/

Update #2 here

Update #1 here
Greetings from Puerto Rico!

I’ll try to keep a daily blog of activities and news from Bioastronomy 2007, one of two (usually) semi-annual meetings in the world of astrobiology. It officially runs from July 15 to July 20. However, I arrived Friday the 13th for AbGradCon, a sorta-annual conference organized by and for astrobiology graduate students only.

They had good funding so we have around 50 participants all over the world. Friday night I drove a car with people from USA, Mexico, Slovakia and Spain. We visited a bioluminescent bay about 2 hours away from the capital of San Juan. After some flailing, we found the departure point, then hit a local roadside pavillion to eat some puerto rican bread and chicken and drink sangria. It was good.

We hit the water and the bioluminescence was cool. Any movement in the water produced green-yellow light. Occasionally a fish would dart by like lightning and the wakes of the kayaks glowed like fire. Putting your hand in the water was like looking at something from that recent Nicolas Cage movie. For ecological reasons you can’t swim, but it was super tempting. The only prob was it was too crowded. You have to kayak for around 25 minutes through a narrow channel in mangrove trees to get to the lagoon. Each group has about 5 kayaks and when we passed there was mass chaos. It is pitch black so you can’t see anything except glowsticks tied to the kayaks. Imagine floating, slow speed bumper cars in the dark.

Yesterday was the 1st day of talks. Some notes:

(Note: I left my abstract list in my room so I don’t have the presenters’ name with me. During lunch break I’ll go back to my room and will update the blog with their names.)

• The theory that most of Earth’s water comes from cometary impacts is losing some of its lustre. The dueterium/hydrogen isotope ratios measured in comets differ from those found in our oceans. However, only a few bright comets have been measured so far thus this could be a selection effect (i.e. comets with these isotopes may tend to be brighter, but not representative of most fainter comets). Thus, the next step is to measure fainter comets, which requires large scopes like those on Mauna Kea. So far, the astronomers have been clouded out during each of their scheduled observing runs.
• It’s possible that high energy particles hitting the surface of Europa can lead to oxidation of the ice and thus be a source of oxygen for a subsurface ocean. Add hydrothermal vents and you get a good recipe for carbon dioxide and methane, two key biomarkers (ingredients for and products of life).
• There has been lots of recent announcements concerning methane on Mars. Most of those come from astronomers and NASA. I’ve noticed here that chemists, the experts in the field, are much more suspicious. They say we don’t understand the chemistry of Mars so we can’t claim to know the sources of any detected methane. It could be life, but it could also be meteoric impacts, radiolysis in the regolith and other processes I couldn’t understand. (I regret not taking chemistry in college.)
• Methane, hydrogen and photons mix well on Titan. And in the laboratory such mixtures always lead to creation of lots of prebiotic molecules. The problem is the lack of oxygen. It was proposed that oxygen could be temporarily released on Titan through cryovolcanism (processes similar to those on Enceladus and Triton) or meteoric impacts. These processes can melt ice on the surface and release oxygen into the atmosphere. What shocked me was the length the melted ice can exist before refreezing. A paper by O’Brien et al. (2005) estimates that an impact of a 15km object would create a melt that lasts about 100-1000 years. A 150km object impact would melt ice for 1000-10000 years, the same as a cryovolcanic dome.

There were lots of nice posters and more info. We’re hoping to setup a wiki or something to post the proceedings (talks, PDFs, etc.). If it occurs I’ll of course mention it on the home page.

These astrobiology graduate students are much better at speaking than your typical professional astronomy conference. Everyone used technology appropriately and defined their jargon. The talks were all over the place: chemistry, biology, astrophysics, etc. And this brings me to the best part of this conference. It’s interdisciplinary, so you meet people that you normally don’t get to hang out with. It keeps the discussions from getting too techie and geeky too. For example, tonight I swam with an evolutionary biologist explaining to me the core debates in the field, a Kinsey Institute researcher describing their wild experiments and two marine biologists with underwater flashlights and goggles, giving us a tour of the beach marine life. How cool is that?

That’s it for AbGradCon. The next update will cover the first day of the official conference, BioAstronomy 2007

Update #1

Hey, all. Here is a summary of some stuff I caught yesterday and today, so far. With the lead author’s name in parenthesis.

• The question of water on Mars isn’t so much whether water exists, but has it ever existed in stable environment. Current evidence points to existence of water, but does not address the issue of stability. His team has been able to define Martian history in terms of three distinct eras. The first era created the phylocilicates and likely included large bodies of stable water on Mars. This lasted about 1.5 billion years and through the early bombardment periods of the solar system. Heat was supplied by volcanic activity and bombardment. The era ended when bombardment ended and also the internal dynamo of the planet (which drives geologic activity) stopped. The next era created the sulfates and consisted of large bodies of water, but they were not stable. This was followed by the current period, which is quiet, dry and has lasted about 3.5 billion years. The important consequence of this theory is that Mars could only have been habitable during that first era. (Bibring)
• The Spirit rover has found evidence of oxidation of iron not caused by liquid surface water. Basically, the red color of Mars is due to very slow oxidation by water vapor in the atmosphere over billions of years. The “dark” areas of Mars are high altitude and just haven’t had time yet to oxidize, but will eventually also become red. Also, Spirit found evidence of early geologic activity and impact changes in the basalt, suggesting a volcanic early history of Mars. At Husband Hill, they found evidence that oxidation can happen without oxygen, which could be an energy source for life in darkness. In other words, sunlight is not needed for life so we should look into dark craters, subsurface areas, etc. (DesMarais)
• RNA and DNA are chiral structures which lead to polarization of reflected light. Thus, li