Wallpaper Wednesday (Submillimetre Astronomy)

14 11 2012

Atacama Pathfinder Experiment (APEX), Chajnantor Observatory, Chile. Photo credit: ESO/H.H.Heyer

Operating on the theory that I am eventually going to finish writing my first book, I’ve begun doing research for my next large project, on early twentieth-century solar and radio observatories. Flipping through the articles on my desk, I ran across one from the 1960s about instruments for observing in the submillimetre wavelength range.[1] Reading it prompted me to wonder if there was any recent news about the Atacama Pathfinder Experiment (APEX) telescope. The search for news from APEX led me to today’s wallpaper.

Every time I visit the ESO website, I’m newly impressed with the online archive. I’ve commented on the image collection before, but the instrument documentation is superb as well. So, too, is the video archive. If you want to learn more about millimetre and submillimetre observations, check out the APEX trailer. Or, you can watch it just because it’s beautiful.


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Click on the image at the head of this post to download the wallpaper.
[1] A. E. Salomonovich, “Some Problems and Instrumental Features of Submillimetre Astronomy,” Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, Vol. 264, No. 1150, A Discussion on Infrared Astronomy (Apr. 24, 1969), pp.

Wallpaper Wednesday (sort of)

7 11 2012

Today, I found a place that has coffee (!) and electricity (!) but no internet (!). Scouring the web for wallpaper images on my iPhone isn’t my idea of fun (have I mentioned how tired I am?), so I’m just going to  copy a link from my e-mail for you. I hope space.com’s gallery of “Experts’ Favorite Space Photos” lives up to its headline.

Wallpaper Wednesday (l’Observatoire de Paris-Meudon)

24 10 2012


l’Observatoire de Paris-Meudon. Photo credit: Matthieu Bourdon

Today’s image is an HDR photograph of the Observatory of ParisMeudon. In 1875, when this branch of the Paris Observatory was founded, Meudon stood outside Paris, in a wooded area against the Seine. Today, Meudon is more of a Parisian suburb (though officially in the arrondissement of Boulogne-Billancourt) and probably best known to foreign tourists as the location of the Musée Rodin Meudon at the Villa des Brillants.

While I was doing research on an unrelated topic this week, I came across several mentions of the Meudon observatory in old astronomical bulletins. I am a big fan of the 19th-century version of the Publications of the Astronomical Society of the Pacific. Each edition is a snapshot of the state of astronomy at the time. The A.S.P.’s founder and president, Edward S. Holden, was a prolific writer (well, he had help from observatory staff) and he culled information from other scientific publications, correspondence with other astronomers, and his own travel and research notes to add to each issue of the Publications. For example, here’s a description of the Meudon observatory as reported by Lieutenant Winterhalter:

The Physical Observatory of Meudon (near Paris).*

The accompanying cut is copied from Lieut. Winterhalter’s Report on European Observatories by the kind permission of the Superintendent of the U. S. Naval Observatory (See Publ. A. S. P., Vol. Ill, page 40). The note here given is condensed from the text of Lieut. Winterhalter’s Report.

The Observatory was founded in 1875 and is established in the park of Meudon, not far from Paris. It is by no means completed, so far as instruments are concerned, but its present facilities are employed in spectroscopic and photographic observations. Its distinguished Director and his assistants have taken part in many eclipse expeditions to all parts of the world, and M. Janssen has prosecuted his spectroscopic observations at all altitudes from the level of the sea, to the tops of the Eiffel  tower, of the Pic du Midi and of Mont Blanc. The solar photographs of the Meudon Observatory are unrivalled. No description of them need be given here, because members of the society can see a beautiful glass copy of one of them which was presented to the Lick Observatory by M.
Janssen, in a conspicuous place in the main hall of the Lick Observatory. E. S. H.

*M. Jules Jannsen, Director [2]

And here is a paragraph Holden reprinted from Scientific American:

Large Refractor for the Observatory of Meudon.

A great refractor has just been finished and placed in position for Dr. Janssen at Meudon. It is a combined photographic and visual telescope. The two lenses were made by the celebrated Henry Brothers, of the Paris Observatory. The mounting is by Gauthier, of Paris. Both lenses will be mounted in the same tube, which is square and of steel. The visual objective is 82 cm. (32.3 English inches) in diameter, while the photographic objective is 63 cm. (24.8 English inches) diameter. Both lenses are of the same focal length, 17 meters (669 English inches.) The large objective will be the guiding part of the instrument when used for photography. This great telescope is housed in the ruins of the old royal palace, a part of the ruins serving as the tower for the great dome, which dome is 20 meters (66 English feet) in diameter and weighs some 60 or 80 tons. The dome is to be moved by a gas engine of 1 2 horse-power. The observing chair is attached to the dome and moves with it. All the fine circles are to be read from the eye-end by means of electric lights, the electricity for which is generated by an 8-horse-power engine half a mile distant, in what was formerly the royal stables.—Scientific American, November 18, 1893 [1]

That’s a lot of information packed into one small paragraph.

If any of my students are paying attention, this is how I start a research project, by tracking back through scholarly publications to the earliest mention of a building (that I can find, at least). I know web searches are tempting, but it’s usually more profitable (and more interesting) in the long run to spend some time paging through back issues of trade journals and professional bulletins instead. Even more interesting would be tracking back through old French publications, but I’m prepared to give you a break on that. This time.

As always, click on the image of l’Observatoire de Paris-Meudon to download wallpaper for your computer.


[1] Edward S. Holden, “Large Refractor for the Observatory of Meudon,”  Publications of the Astronomical Society of the Pacific, Vol. 6, No. 34 (January 27, 1894), pp. 46-47

[2] Members of the Staff and E. S. H., “The Physical Observatory of Meudon (Near Paris),” Publications of the Astronomical Society of the Pacific, Vol. 4, No. 25 (September 3, 1892), p. 181


Wallpaper Wednesday

17 10 2012

Milky Way, Southern Cross, alpha Centauri, Carina Nebula. Photo credit: A. Fujii

Threaded through the partisan bickering during the debates on twitter last night was a string of tweets discussing ESO’s discovery of a planet in the Alpha Centauri system.[1] According to ESO’s press release, the planet was detected through the observation of “wobbles” in Alpha Centauri B’s path of motion. Astronomers speculated that the gravitational pull of an orbiting body was generating the irregularities. Putting the HARPS instrument on the 3.6-metre telescope at the La Silla Observatory to work on the problem, they discovered a planet with an orbital period of 3.2 days. The twitter is excited because Alpha Centauri B is a lot like our Sun and the newly discovered planet has the same mass as Earth—the theory being that our planetary twin has been discovered orbiting the star closest to our solar system. I’m not too worked up about the twinning possibilities, but I do think it’s cool that HARPS is doing exactly what it was supposed to do: find new planets.

In related news, I was intrigued by NASA’s response to ESO’s announcement. It’s as if they’re taking the discovery of the new planet a bit personally. Their press release, ostensibly a statement of congratulations to ESO on its accomplishment, reads more like an attempt to stake a claim on exoplanets of the universe. “We, too, have exoplanet finding capabilities! We have Hubble! We have Kepler! We have the James Webb Space Telescope!”

Click on the image to download wallpaper.


[1] Two stars comprise the Alpha Centauri system, Alpha Centauri A & B. They are indistinguishable to the naked eye, so we usually refer to them in the singular, as in “Alpha Centauri, the brightest star in the constellation Centaurus.”

Wallpaper Wednesday

11 10 2012

SpaceX’s Falcon/Dragon Launch. Photo credit: NASA/Tony Gray and Robert Murray

I missed posting yesterday. I was on the road (on the train, in the plane) all day. As you might have guessed, I’m writing this from Los Angeles, where I am preparing for Endeavour’s final move. The big event begins at 2 a.m. this evening and last two days—wish  my old bones luck!

Last weekend, I had the good fortune to be in Virginia. While there, I did something you should never do: pulled out my iPhone during a family dinner and propped it up on the serving dish in front of me so I could watch NASA TV’s pre-launch coverage of the SpaceX Falcon/Dragon launch.[1] Eventually, my phone was passed around the table while my partner and I explained why we were so interested in the launch. By the end of the meal, the TV in the living room was playing NASA TV instead of football. By launch time, fourteen people were sitting in front of the television, counting the seconds to liftoff. Thank god the launch didn’t scrub at T-1 second—that’s a lot of pressure, a room full of relatives!

Congratulations once again to SpaceX. People are paying attention and that’s a good thing for the future of space exploration.


[1] In my defense, a few members of the extended family were eating dinner in front of the television—baseball/football—so I wasn’t being THAT rude.

Wallpaper Wednesday

3 10 2012

Celestial Conjunction at ESO. Image credit: ESO/Y. Beletsky

Today’s wallpaper, which shows the moon, Venus, and Jupiter having a conversation above  ESO’s Very Large Telescope (VLT) celebrates two things: the observatory’s 50th anniversary and the publication of the book Europe to the Stars. ESO is second only to NASA in its release of images to the public, and in the realm of astrophotography, it dominates in its generosity. I could easily provide a wallpaper image a day just mining ESO’s extensive web collection, but where the fun be in that? You can waste as much time as I can digging through their archives.

Wallpaper Wednesday

27 09 2012

Gemini North with Southern Star Trails. Image credit: Gemini Observatory

I completely forgot yesterday was Wednesday. Rather, I remembered, but only as “Today is Wednesday, the day I talk to my developmental editor,” not as “Today is Wednesday, the day I remember that I have a blog I’m supposed to update at least once a week.”

It’s just as well I missed my regularly scheduled update because now I can write about yesterday’s press release from Gemini Observatory. The observatory announced that its astronomers have produced the sharpest image yet made using ground-based (Earth-based) instruments of Pluto and its largest companion, Charon.

Speckle image reconstruction of Pluto and Charon obtained in visible light at 692 nanometers (red) with the Gemini North 8-meter telescope using the Differential Speckle Survey Instrument (DSSI). Image credit: Gemini Observatory/NSF/NASA/AURA

The pixelated image might not look like much, but as the press release noted, it’s “the first speckle reconstructed image for Pluto and Charon from which astronomers obtained not only the separation and position angle for Charon, but also the diameters of the two bodies.” That’s pretty exciting—if anyone has tried to sell you the diameter of Pluto recently, he or she should have prefaced the number with the word “about.” Astronomers have been setting upper limits on the diameter since Pluto’s discovery in the 1930s (the 1960s seemed to be a particularly fertile decade for arguments on the topic), but still qualify their assertions with “± 20km”. I’ve been looking forward to the New Horizons arrival at Pluto in 2015, but the Gemini announcement makes the wait a little less painful.

Of everything I’ve read today, the comment I enjoyed most was made by Elliott Horch, coauthor of the Gemini study:

This was a fantastic opportunity to bring DSSI to Gemini North this past July. In just a little over half an hour of Pluto observations, collecting light with the large Gemini mirror, we obtained the best resolution ever with the DSSI instrument—it was stunning![1]

First, you gotta love the enthusiasm. I recently heard an NPR story about the development of robotic intelligence. The claim was that one day, humans would stop experiencing the “A-ha!” moment because robots would do all our thinking for us. I’m guessing Elliott Horch wouldn’t agree with that premise.

Second, the comment about “just a little over half an hour” caught my attention. It’s a little misleading, of course. As Horch knows, since he was in charge of the project to develop the instrument, hours and hours and hours went into the design and installation of the Differential Speckle Survey Instrument (DSSI).[2] But then again, this is how contemporary astronomy works: you request a time slot on a popular instrument and pray the weather, the instrument, and everything else in the universe that can affect your project goes the way you want it to go. Sometimes you get an entire evening with an optical instrument, sometimes you get a few nights, sometimes you have to change your project because there’s no open time available at all. When everything works out, well, then  you see Charon and Pluto.

Today’s wallpaper celebrates the Gemini/DSSI/Korch team victory. Click on the observatory and star trails to reach the download page.


[1] Gemini Observatory Takes Sharpest Ground-Based Images Ever of Pluto and Charon (redOrbit.com)

[2] DSSI was installed temporarily at Gemini North last summer. It’s spent most of it’s observing life at Kitt Peak.

Wallpaper Wednesday

12 09 2012

Helmos Observatory, Peloponnesus, Greece. Photo credit: Harry Katzjaeger

Today’s wallpaper is apropos of nothing in my life right now. Rather, it’s a beautiful image of the night sky above Helmos Observatory, home to the 2.3 meter telescope ARISTARCHOS. Helmos might be placed in one of the most beautiful parts of the world (if you don’t believe me, check out the observatory’s image gallery).

Click on the image to go to the appropriate National Geographic wallpaper download page.

Wallpaper Wednesday

5 09 2012

Dawn Orbiting Over Vesta. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Today NASA announced that Dawn has escaped the asteroid Vesta’s gravitational pull. The spacecraft is now “officially” on its way to Ceres, the first dwarf planet detected by humans. Stop by the mission website to watch Dawn’s Greatest Hits, a splashy video highlighting the research accomplishments at Vesta, the most interesting of which were a series of discoveries that led to the conclusion that Vesta resembled a minor planet more than an asteroid. Dawn’s work at Ceres will be exciting: what started out as a comparison between an asteroid and a dwarf planet has turned into a comparison between two different types of small planets. Check out When is an Asteroid not an Asteroid? for more on that story.

Dawn’s Greatest Hits:


Farewell Portrait of Giant Asteroid Vesta:


Click on the image at the top of the post to download the wallpaper.

Wallpaper Wednesday

29 08 2012

Red Moon Rising. Photo credit: ESO/G. Lombardi

Today’s wallpaper features a couple of my favorite things: the Paranal Observatory and a full moon. Gianluca Lombardi took this photo of one of the Auxiliary Telescopes (AT) at Paranal, using the colors of the sunset to their best advantage. Visit the ESO website to read more about light scattering, the red moon effect, and the role of the AT in the VLT Interferometer (VLTI).

Click on the image above to download the wallpaper or the original photo (download links will be in the page’s right sidebar).