The HARPS-N team in front of the Italian National Telescope (TNG) Photo: Manuel Gonzalez

The HARPS-N spectrograph was inaugurated on April 23rd. Here’s some photos.

Francesco Pepe from Switzerland explaining the spectrograph, which is in the foreground. Photo: Manuel Gonzalez

Better late than never, I hope.

Michael Mayor symbolically cutting the fibre. Left to right: Mave, Michael Mayor, David Latham, Emilio Molinari, Guiddo, Francesco Pepe. Photo: Manuel Gonzalez

The scale models of the Earth and Mars

Palacio Salazar in Santa Cruz de La Palma is hosting a great exhibition on the Earth and Mars until May 26th. It features lots of great photos of Mars, and explains the similarities and differences in geology, atmosphere and weather, and hydrology. Even better, they have a genuine meteorite from Mars.

Did you know that a day on Mars lasts 24.6 hours compared to our 24? And the axial tilt is 25º, compared to our 23º. Mars is 50% farther from the sun than the Earth, and therefore receives just 44% as much sunlight, but its thin atmosphere is largely carbon dioxide and the greenhouse effect means that it’s not all that much colder. A cold winter’s night can drop to -87 ºC, and a baking hot day can reach 20 ºC. That’s similar enough to the Earth that Mars also has sand dunes and dust devils. The exhibition includes a selection of photos for you to guess which planet you’re looking at before you lift the flap for the correct answer. I didn’t get them all right.

The exhibition is open from 9 am to 1 pm and 5-8 pm, Monday to Friday, and on Saturdays from 10 am to 2 pm.

The Liverpool Telescope, open at sunset.

The Liverpool is the joint largest robotic telescope in the world, with a 2 m mirror. Since there’s nobody at the telescope at night, it was built with very little in the way of workshops. But the new building contains a workshop to assemble and test new instruments, and a control room, to help humans commission them. Of course the workshop will also make routine maintenance of existing instruments much easier. And there’s a store room for spares, to keep them handy.

The Dodo Dragon and Other Stories

Nine quirky SF stories by Sheila Crosby (the author of this blog) to entertain you. Two of the stories are set on La Palma.
On sale April 23rd 2012, and available for Kindle, iPad, Mac and PCs.

Cover painting by Merche Martin Morillo
Layout by Eco-geek

This book currently has 4.5 stars on Amazon.com, but it’s slightly cheaper from our own products page, which also offers other electronic formats.

If you have any problems with this book, please click on “Leave a reply”.

If you like it, please tell as many people as possible!

The Galileo telescope and the milky way. Photo: Gianni Tessicini

The Italian National Telescope (the Galileo) is getting a new scientific instrument to look for planets outside our solar system.

I remember a childhood astronomy book which said that we would never know whether there are planets outside our own solar system, because they are much, much too small and much much much too far away.

That’s all changed in the last few years.

There’s a class of instruments called spectrographs which put the light through a prism or grating to separate the starlight into a rainbow. Here’s the clever part: rather than a continuous smear of colours, starlight has thin black lines missing. It looks like a fine barcode printed on top of the spectrum. These dark lines are called absorption lines, and each chemical element produces it’s own, distinctive barcode. They’re a result of quantum physics in the structure of the atom. (Please don’t ask me to explain the maths, or I’ll start to whimper.) So by studying the spectrum of a star, an astronomer can tell which chemical elements make up the star. By looking at the relative intensity of different lines on the same barcode, they can also tell how hot it is. And there’s more.

If you listen to an approaching police car or ambulance, you’ll hear the pitch of the siren change as it passes you. As the car comes towards you, the sound waves get squished together, making the pitch higher. Then as the car passes the pitch drops, because now the sound waves are being stretched out, creating a deeper note. This is called the Doppler effect. The faster the car’s moving, the bigger the effect.

The same thing happens with light. If a star is moving towards us, the light waves get compressed, and so the star looks bluer. If it’s moving away, the light waves get stretched, so the star looks redder. The amount its light gets shifted depends on its speed.
How do we know what colour the star was before the light got shifted?

You need a barcode that you know hasn’t been shifted to compare with the same barcode from the star. That makes the amount of shift very obvious. So practically all spectrographs have special lamps, called calibration lamps, to provide this.
So that’s the chemical composition of the star, the temperature, and its movement, all from a boring-looking barcode.

When you were a kid, did you ever fill bucket with water, and then whirl around with the bucket at arm’s length, so that the centrifugal force kept the water in place? If you watch somebody doing that (borrow a seven-year-old) you’ll see the person moves from side to side as they spin, pulled off-centre by the bucket. The bigger the bucket, the more the wobble. In a similar way, an orbiting planet makes its parent star wobble. The catch is that the bucket weighs perhaps 5% as much as the kid, whereas planets are usually tiny compared to the star, so it’s a very tiny wobble. The biggest known planet is 1/7 the mass of the smallest known star, but that’s highly unusual. Our sun weighs over a thousand times as much as the biggest planet in our solar system, which is Jupiter.
So at first the wobble technique only worked for unusual planets, the so-called “hot Jupiters”: hot because they’re unusually close to the star, and “Jupiters” because they’re enormous (Jupiter weighs as much as 317 Earths).

The Galileo Telescope’s new spectrograph (HARPS-N – High Accuracy Radial velocity Planet Searcher – North) works using the same technique, but since they’re hoping to find earth-like planets, they’ll need to spot the star moving at about 1 m/s, which is a slow walking speed.

That’s impressive accuracy, and it doesn’t come easy. For a start, the instrument itself is housed in a clean room inside a triple enclosure. Each enclosure is temperature controlled, and the innermost one is a vacuum, with the temperature kept stable to within 0.01 ºC.

It’s a near-copy (slightly improved) of an instrument that’s been working in Chile (HARPS-S, but with improved optical fibres.

The first fibre collects light from the star. The second fibre can be used to collect either the sky background, or a reference lamp (with the absorption lines in a known place) to compare with the starlight.

The plan is to look at promising stars discovered by a NASA satellite called Kepler which looks for stars whose light periodically dims just a little, as though a planet is passing between the star and the satellite.

Spectrographs are common enough, but HARPS-N might just find another planet we can live on.

Cover design for 'A Breathtaking Window on the Universe'

This is the cover design for my ebook, “A Breathtaking Window on the Universe: a guide to the Roque de Los Muchachos Observatory”, which should be on sale by late summer or autumn of 2012. It explains why the observatory is on La Palma and how a telescope and its instruments work, and gives details of each telescope, plus many anecdotes and over 60 photos. I’ll be posting full details here when it’s available.

Looking south and west from Las Toscas astronomical viewpoint

There is a new astronomical viewpoint above Mazo at Las Toscas.  Like the others, it has parking space, level ground suitable for tripods, a signpost pointing to the pole star, and an information panel. This one has information about noctural wildlife on La Palma: bats, owls and crickets. It’s well away from street lights, although it does give a great view down to the island’s airport.

To get there, take the LP1 to just south of Mazo (between km 7 and 8, and then the LP2062 (signposted PIRS). Follow this for 1.7 km, and then take the concrete track to the left (signposted “Mirador de unreadable”) for half a kilometre.

One of the information panels at Las Toscas viewpoint

(No, I don't think it's real. Just really cool.)

A Happy Valentine’s day to all my readers. I hope you all have someone to hug.

La Muralla viewpoint has a display panel about the moon.

The astronomical viewpoint in Tijarafe is now open. It’s easy to find, right beside the main road (the LP1) at km 83, which is about 2 km north of the main village of Tijarafe, right beside a restaurant with a good reputation. It’s not the darkest viewpoint, but it must have a terrific view of the sunset.

Each astronomical viewpoint on La Palma has information panels, and those at La Muralla specialise in the moon, including a little about its place in the mythology of the Awara, the pre-Hispanic inhabitants of La Palma.  It also has the usual signpost to the Pole Star.

The restaurant is closed on Mondays, and opens from 1 pm – 10pm, although the kitchen is shut from 5-7pm Tel: 660322305