Victorian Era Illustrations of Space

This is really cool.  Check out this gallery of Victorian Era illustrations from the Harvard College Observatory.  Here's Jupiter:

The Impending Dearth of Space Observatories

I mentioned this in class.  Currently, there are a huge number of NASA-funded telescopes in space taking data for astronomers.   But that's all about to change.  Within the next couple of years, the telescopes will be rendered useless due to limitations both physical (eg. running out of cryogen), and fiscal.  Check out the plot.   In the last 10 years, we've been blessed with a large number of phenomenally powerful space telescopes.  In the next ten years, there will far less data coming in.  Fortunately, there's still plenty of science to do with the data we have.  And the outlook for ground-based telescopes isn't quite so bleak, as ALMA and eVLA are both coming on line soon.

Big Glass in the News

NPR had a nice story on Morning Edition about the making of the mirrors for the next generation of optical/infrared telescopes.

Here's a picture of the glass pieces being arranged before being melted down.

Telescopes in Space!

Friend and colleague Jane Rigby, of the Goddard Space Flight Center, gives a TED talk on putting telescopes in space.  It isn't cheap, but it is awesome.

Not Breaking News: Blogs Upset the Establishment

The NY Times has a piece on the growing trend of having high school and college students write blogs rather than term papers.

About the latter:

“This mechanistic writing is a real disincentive to creative but untrained writers . . .”


Agreed.

This is a galaxy

A collaborator of mine, Andrew Pontzen, just posted this cute little video.  Very cool.

Your Blogs

Most of you have set up a blog and sent me the URLs.  Things look great.  There's a wide variety of posts, both in content and style.  Keep it up!

Jose Aresti:  BetelguesLeoOphiuchusGemini
Kevin Aylor:  Kevin Aylor's Astronomy Blog
Louise Bonilla:  My Physics Blog
Louis Bran:  The Starry Night
Gabriel Cecchini: AEGIS
Kyle Chan:  It's Astrotime
George Christensen:  Astronomy
Daniel Diaz:  phys111
Jason Drury:  Celestial Illumination
Vitaly Fedotov: Astroglade
Jacob Freeman:  What do astronomers do?
Matthew Gonzales:What an astronomer does
Joshua Hacker:  ASTROPHYSICS 101
Joseph Jimenez:  Astrophysics and Stellar Astronomy
Joshua Kast:  Physics, Complicated
Kyle Lee:  Astronomy Blog
Sarah Lewis:  First Light
Matthew Maldonado:  The Awesome Astrophysics Blog
Christopher Mendez:  Astrophysics and Stellar Astronomy
Deborah Mercado:  Astronomy
Andrew Nguyen:  Nox Caelum
Phi Trieu Nguyen:  Shooting Stars
Tuan Nguyen:  To Infinity and Beyond!
Parth Patel:  Numbers Within Physics
Luka Ratkovitch: Constructive Interference
Brandon Ricafrente:  Lumpy Space
Samantha Rorick:  I Know Some Of These Words
Daniel Ryan:  Are You Sirius?
Natalie Schram:  From Darkness There Springs Light
Kevin Simms:  Kevin's Astronomy Blog
Marissa Smirnoff:  Epiception
Alan Tam:   The Blazar Effect
Carter Walker:  Cosmic Infernos

And of course, mine:
UCR PHYS 111 Blog

Toward Solving the Drake Equation

The Drake equation is an attempt to quantify the number of detectable alien civilizations (N) in the Milky Way galaxy.  Here's the equation:

R* = Star formation rate in the galaxy
f_p   = Fraction of stars with planets
n_e   = Average number of planets per star that can support life
f_l    = Fraction of suitable planets that develop life
f_i    = Fraction of above that develop intelligent life
f_c   = Fraction of civilization that emit detectable signals (eg. radio waves)
L    = Length of time over which above civilizations emit the signals.

The equation is useful in that it demonstrates how utterly ignorant we are about this topic.  Depending upon the various assumptions made about each of the above variables, the galaxy is either teeming with life, or we're the only ones here.

Well, astronomy has made some progress on the first few variables.  In recent years, all-sky infrared surveys have mapped the star-forming regions in the galaxy, and they claim star formation rates of ~2-3 solar masses per year.  Basic info here.  Great, so that's one variable with a reasonable estimate.  Only 6 more to go, but these are much harder to determine.

In an exciting new development, astronomers have announced that they have a reasonable estimate of the second variable, the fraction of stars with planets.  The article, published in the January 12 issue of the Nature, estimates that stars in the Milky Way average at least 1 planet per stars.  Well how many stars are there in the Milky Way?  Answer: A few hundred billion!!  So if each one has at least one planet, that's a LOT of planets.  This is great, but how did they determine this number?

Well, they monitored stars for a phenomenon called gravitational microlensing (or just microlensing to the cognoscenti).  Microlensing occurs when a massive object passes in front of a star.  Because the gravity from the object can bend the light (as predicted by Einstein), it can act as a lens, effectively magnifying the light seen from the background star.  This technique had been used famously by the MACHO Project in the 1990s to determine if much of the "dark" matter in the galaxy was simply planets and brown dwarfs (it isn't).

The published result is from the PLANET collaboration, which has been monitoring high magnification events from large area microlensing surveys such as OGLE.  As shown in the illustration above, every once in a while, during a microlensing event from a star, an additional lensing will occur (over a shorter duration) by a planet companion of the lensing star.  The great thing about microlensing searches for planets is that they're more sensitive to planets at larger orbital radii, whereas transit and radial velocity techniques are efficient at finding planets that are very close to the star.

Though the numbers are quite small, the authors suggest that smaller planets similar to Earth are more common than Jupiter mass planets.

So, we now have at least a decent estimate for two of the seven variables in Drake's equation, and we're investigating a third.  The astronomers are doing their part.  I'd like to hear from the biologists and anthropologists what their best guesses are for the other four.