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News, anecdotes and pictures from across science and engineering at UCL


Archive for the 'Mathematical & Physical Sciences' Category

First person: 8.3 magnitude earthquake hits Chile

ucapola23 September 2015

A combination of high mountains, clear skies and bone-dry deserts makes the north of Chile one of the world’s best places to observe the sky. Numerous international observatories are located there, and astronomers from around the world frequently travel there to carry out their research. Ofer Lahav, Perren Professor of Astronomy at UCL, was there during the magnitude 8.3 earthquake of 16 September. This is his personal account of the events.

Cerro Tololo Inter-American Observatory. Photo: Ofer Lahav

The Blanco 4-metre telescope at Cerro Tololo Inter-American Observatory. Photo: Ofer Lahav

The Earthquake started on Wed 16 Sep at 19:54 (local time), just as we were preparing for the start of DES (Dark Energy Survey) observations.

We left the telescope immediately, and moved to the shaky ground outside the dome. Eventually we were evacuated from there to the CTIO dining hall.

The team was evacuated to the observatory's dining hall - Ofer Lahav is leftmost.

The team was evacuated to the observatory’s dining hall – Ofer Lahav is leftmost.

After-shocks continued throughout the night, but the oscillations finally decayed.

The following morning was sunny and quiet. Observations resumed the following night.

Boulders dislodged from the mountainside and fell onto the road near the observatory. Photo: Ofer Lahav

Boulders dislodged from the mountainside and fell onto the road near the observatory. Photo: Ofer Lahav

I left next morning as planned, flights were on schedule.

We were all impressed by the way the observatory staff handled the situation efficiently and calmly.

It is re-assuring that the system, in part assembled at UCL, is working so well – the only obstacles between the DECam instrument and the galaxies are the Earth’s atmosphere and quakes…

The astronomers who didn’t stop for a missile strike (or a flat battery)

Oli Usher18 September 2015

This remarkable document comes from the observing log of the University of London Observatory. The observatory is now a UCL teaching facility and part of the Department of Physics & Astronomy, but at the time was an important research facility.

It reveals the effect of the Nazi bombing of London during the second world war.


UCL’s Bloomsbury campus was severely damaged in raids early in the war, with the Library’s dome destroyed and the historic buildings around the main quadrangle all gutted by fire.


Relentless bombing from aircraft early in the war, then by V1 and V2 missiles later in the war brought the conflict close to Londoners, and the unperturbed tone of the log makes clear how commonplace it had become – even in the quiet suburban environment of Mill Hill, where the observatory is located.

The log reads:

1944 August 3

Opened 21h. Sky clear.

Found red light on spectrograph not workingm, owing to plug having been left in and battery run down. Set on γ Cas with the help of dark room red light.

I started exposure at 21h 44m GMT.

Flying bomb exploded very close and shifted star in declination out of the field.

Star recovered and exposure restarted at 21h 47m GMT.

Just after starting the second time, a second flying bomb exploded. This was more distant and though it shifted image from the [spectrograph] slit, star did not go out of field and was quickly recovered.

Exposure ended 22h 07m GMT.

Exposure time = 20m.

Plate developed.

Closed 22h ½.


The event was a V1 flying bomb strike on nearby Hendon, which killed eight and destroyed 193 houses.

The signatures on the end of the document are of historical note too – alongside CCL Gregory, the director of the observatory, was EM Peachey. She is better known today under her married name of Margaret Burbidge. At the time, she was a young astronomer who had just passed her PhD, but she went on to become one of the preeminent astrophysicists of the twentieth century.

The observatory will be holding a one-day astronomy event in the Quad on 2 October, and an exhibition of astronomical images produced by UCL staff and students using its telescopes will be held along the walls of the North Cloisters throughout the term.



Why chemistry labs need expert glassblowers

Oli Usher11 September 2015


Chemistry labs need skilled glassblowers to produce some of the intricate, bespoke glassware for some of their experiments. This item, produced by one of UCL’s glassblowers, is designed to be placed on a heat source so it can distill liquids and deposit them in ampoules along its long stem.

The flask’s design includes bell-shaped edges inside to encourage the liquid to evaporate evenly. The gas then cools and condenses inside the long stem, collecting at the end. When enough has collected there, the end of the stem can be melted off, sealing the liquid safely inside.

Time turns backwards at the Spark Festival

zcahe9128 August 2015

While real time travel may be theoretically possible, it almost certainly won’t happen in our lifetimes. However, at the Spark Festival this weekend, the Chalkdust team will have a very surprising demonstration where we can turn time backwards.

For a sneak preview, watch this video of a Taylor-Couette cell (sound not necessary):

Surprised? I certainly was when I saw it for the first time.

For those who couldn’t watch the video: at first, blobs of coloured syrup are dropped into some clear syrup. Then the colours are mixed up by turning a tube inside the cylinder, until they look all brown. However, the tube is then turned back the other way, and the coloured liquid completely unmixes, ending up in the same blobs as they started. It looks exactly like the video has played backwards. It’s called reversible flow, and we’re very excited to have our own Taylor-Couette cell at the festival, where people of all ages can have a go at turning back time.

Airplane_vortex_editNow you might be thinking – what’s that got to do with maths?


A balanced view of radon

Oli Usher27 August 2015


Thin, fragile, light, and barely visible against the padding that keeps it intact, this object is nevertheless reflects an important period in the history of chemistry – a period in which UCL led the world.

Around the turn of the 20th century, UCL’s chemistry labs saw most of the key discoveries related to the noble gases. William Ramsay isolated helium and argon here in 1895, and went on to discover krypton, neon and xenon in 1898. Over the next few years, experiments at UCL proved that radon, discovered by Friedrich Dorn in Germany, also belonged to this group. (Ramsay won UCL’s first Nobel Prize for his work on these gases.)

The delicate quartz balance in the image above is one of the most important pieces of apparatus used in this research on radon. It was used by UCL chemist Robert Whytlaw-Gray to weigh a sample of radon and determine its density for the first time. A schematic of the balance is shown below:


The balance held a tiny sample of radon in the chamber on its right, and was balanced inside a vacuum flask with a weight attached to the balance’s other side. Despite the tiny quantity of gas involved, this was enough to determine radon’s properties.

It is held by UCL’s chemistry collections, along with other artifacts relating to this period in UCL’s history, including William Ramsay’s Nobel Prize medal and citation.


Cantilevers for diagnosing disease

Oli Usher21 August 2015

cantileversThis tiny device, developed by researchers at the London Centre for Nanotechnology, could soon help carry out difficult medical diagnoses.

The tiny rods, or ‘cantilevers’, are coated with molecules similar to those in our cells, which have been made sensitive to various diseases. In their work, the team have successfully made coatings which react with molecules that are part of HIV, the antibiotic Vancomycin, and blood anti-clotting factors (for haemophilia).

When in the presence of one of these molecules, the cantilever bends (as seen above), revealing the diagnosis.


The most distant galaxy

Oli Usher6 August 2015

EGSY8p7 The blurred, faint, orange speck at the centre of this image may look unremarkable, but it is the most distant galaxy ever to have been confirmed by scientists. Called EGSY8p7, the galaxy was identified by UCL PhD student Guido Roberts-Borsani in the Hubble image above, based on its unusually reddened colour profile.

Followup observations using the WM Keck observatory by a team including Roberts-Borsani and UCL astrophysicist Richard Ellis have confirmed the find. Splitting the light into its component colours, the spectrograph at the observatory showed that the galaxy’s spectrum was shifted far towards the red end of the spectrum by the expansion of the cosmos. This ‘redshift’ is an unmistakeable sign of an extremely distant object.

It is at a redshift of 8.68, meaning we see it as it was when the Universe was only about 4% of its current age. Its light has been travelling for over 13 billion years on its long journey to us.

Read more about the research.

Vintage space: Venus in 1991

Oli Usher28 July 2015

On 5 May 1989, the Space Shuttle Atlantis released the Magellan probe into low Earth orbit.

A short while later, Magellan’s rockets fired, sending it towards the sun.

Magellan being deployed from the Space Shuttle Atlantis on 5 May 1990. Photo: NASA (public domain)

Magellan being deployed from the Space Shuttle Atlantis on 5 May 1989. Credit: NASA

Swinging around our star, it arrived at its destination 15 months later: the planet Venus.

Venus is in some respects the most Earth-like planet in the Solar System. It is a similar size to our planet, has a rocky surface and a thick cloudy atmosphere. However, it is much closer to the sun, and thanks to its atmosphere, experiences a powerful greenhouse effect.

The planet Venus, seen by Mariner 10. Credit: NASA (processing by Ricardo Nunes)

The planet Venus, seen by Mariner 10. Credit: NASA (processing by Ricardo Nunes)

Surface temperatures there are well over 400 degrees Celsius, atmospheric pressure is similar to what submersibles experience a kilometre down into Earth’s oceans, and the ‘air’ of Venus’ atmosphere is full of sulphuric acid.

Exploration of Venus’ surface has been in the form of brief snapshots, taken in the few tens of minutes that landers survive the harsh conditions there. All the landers so far have been Soviet; UCL has a number of their photos in its Centre for Planetary Sciences’ image archive (with a selection available online in high resolution).

The surface of Venus seen by the Venera 13 probe. Credit: UCL RPIF

The surface of Venus seen by the Venera 13 probe. Credit: UCL RPIF

Observing Venus from space is less challenging – and less rushed.

Between 1990 and 1994, Magellan was able to study the planet’s surface at leisure from its position high above the atmosphere. Because of the thick clouds, its images had to be produced by radar rather than optical photography, so they are not in colour. But they are extremely sharp.

Here is one of these images, held in UCL’s archives:


One of Magellan’s radar images of Venus’ surface. (The image is squint in the original!). Credit: UCL RPIF

Most of the highly processed images from Magellan are produced by multiple passes of the spacecraft over the planet’s surface, building up a complete image of the surface. This particular picture, however, is incomplete, revealing how Magellan’s images are put together. The black stripes show the gaps between the strips observed during different orbits of the planet.

Also in UCL’s archives are some of the planning documents NASA produced as part of the mission, including this full map of the planet’s surface:


Planning chart for the Magellan mission. Click here for labelled image showing the location of the above radar map. Credit: UCL RPIF






Five years of Arctic ice

Oli Usher21 July 2015


Five years of sea ice changes in the Arctic. (Click picture to start animation)

New research from scientists at UCL and the University of Leeds shows an unusually cool summer in the Arctic in 2013 led to a boost in sea ice. The research, carried out with the European Space Agency’s CryoSat-2, gives researchers of the fluctuations in ice between years, and suggests that pack ice in the northern hemisphere is more sensitive to changes in summer melting than it is to winter cooling.

The image above (click to animate it) shows the variation recorded by CryoSat-2 from 2010 to 2014.

Photo credit: ESA/CPOM (free for most uses – see conditions)

Pluto and Charon: A planetary waltz

ucrhmon14 July 2015

NASA’s New Horizons probe is flying past Pluto today, after years of travel. It is the first ever probe to visit the Pluto system. Here, Minna Orvokki Nygren (UCL Science & Technology Studies) describes a unique art-science collaboration commissioned by UCL & Birkbeck’s Centre for Planetary Sciences to celebrate the event.

Pluto and its moon Charon, seen by New Horizons last week. Photo: NASA

Pluto and its moon Charon, seen by New Horizons last week. Photo: NASA

Pluto and Charon – A Planetary Waltz was composed in collaboration between composers Catherine Kontz and Minna Orvokki Nygren. The work was commissioned by the Centre for Planetary Sciences UCL/Birkbeck (CPS) and it received its premiere on the 24th of June 2015 at An Evening with the Planets event at the UCL by pianists Valentina Pravodelov and Kerry Yong.

The main organiser of the event, Professor Steve Miller’s support and enthusiasm towards the project were crucial in realising this new work.

The piece was inspired by two photographic plates that led to the discovery of Pluto in 1930 by amateur astronomer Clyde W. Tombaugh.

The discovery images of Pluto

The discovery images of Pluto

These plates were used to devise the overall form for the musical work. The distance the bodies travelled across the sky and their relation to other bodies was reflected in the music. When seemingly further away from other celestial bodies, the warped “waltz” of Pluto and Charon, written in 5/4 time, takes over with its prominent bass line and thick chords.

A key aspect of the composition is its gestural dimension which the pianists take on during performance, such as switching seats with each other as in an “orbital ballet,” or the use of custom planetary mallets applied to the piano interior marking off specific movements in the piece.

Other features, such as the size, temperature, consistency and albedo of the bodies were also part of the compositional process. The dwarf planet Pluto being approximately twice the size of Charon is given a more powerful and majestic voice in the work, while its counterpart Charon’s music is lighter, slower and mysterious. The Kuiper belt’s chilly conditions are reflected in the piece by combining extremely high and low pitches of the piano, and giving them an ethereal resonance through the use of distinct pedalling.

An illustrated score of Pluto and Charon was created to give the audience an opportunity to follow the movement of the bodies and the musical piece.

Illustrations from the score (© Minna Nygren, all rights reserved)

Illustrations from the score (© Minna Nygren, all rights reserved)

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