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Archive for the 'UCL Science Picture of the Week' Category

Simplifying complex data

By Oli Usher, on 27 October 2014

One challenge in science is how to represent vast datasets in a way that the human eye and brain can understand. UCL statisticians Sofia Olhede and Patrick Wolfe have worked on methods of simplifying data on relationships between things in a way which captures all the important features, but is not so unwieldy that the patterns are lost.

blogs contour

The top pair of images on this page show data on how frequently blogs supporting different parties link to each other – showing frequent linking between fellow US Republican Party blogs and US Democratic Party blogs (top and bottom quadrants of the picture) but very little crossing the political divide (left and right quadrants). Peaks (in red and yellow) show groups of blogs that link to each other frequently, blue areas show combinations of blogs that rarely never link to each other. The lower image is a 2D map of exactly the same data.

The next image shows a mathematical approximation of the shape of the distribution of linking in that data – showing how the underlying pattern of blogs linking to each other is actually rather simple.

blogs idealized

 

A detailed article on the science behind these images – and what they tell us – will be published here on the UCL Science blog on Wednesday.

Picture credits: Patrick Wolfe, Sofia Olhede (UCL Statistical Science).

Data from Adamic and Glance

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Marvellous maps

By Oli Usher, on 20 October 2014

Part of George Greenough’s 1819 geological map of England & Wales, showing modern-day Cumbria (then Cumberland and Westmoreland)

Part of George Greenough’s 1819 geological map of England & Wales, showing modern-day Cumbria (then Cumberland and Westmoreland)

This picture shows part of George Bellas Greenough’s 1819 geological map of England and Wales – the first to comprehensively map what lies beneath England’s countryside. This page shows the counties of Cumberland and Westmoreland (modern Cumbria).

Greenough was a pioneering geologist of the 19th century who left his collections to UCL when he died in 1855. (His name is commemorated in UCL’s Earth Sciences student society, the Greenough Society.)

Some of Greenough’s maps, along with other historic items from UCL’s Geology Collections, were publicly displayed on Friday as part of Earth Sciences week.

 

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Space Shuttle commander visits UCL Academy

By Oli Usher, on 13 October 2014

NASA Administrator Charlie Bolden (right) with UCL Academy principal Geraldine Davies (left)

NASA Administrator Charlie Bolden (right) with UCL Academy principal Geraldine Davies (left)

Last week saw Charlie Bolden – a former Space Shuttle pilot who now heads up NASA – visit UCL Academy. In this week’s Picture of the Week, he can be seen visiting the school’s facilities with the principal, Geraldine Davies.

UCL Academy is a non-denominational state school in Swiss Cottage, around two miles north of UCL’s central London campus. The school, which is sponsored by UCL, educates local children and charges no fees, and has extensive input into its teaching from UCL academics and students. It opened in 2012, and recently sent its first student to UCL – to study chemistry.

Bolden gave an inspirational talk to students, and was mobbed by students as he toured the school afterwards.

UCL space scientist Lucie Green, who arranged the visit (and is one of the school’s governors), said: “UCL has a long history of working with NASA that began shortly after its formation in 1958. Today, we have an extended family that includes the UCL Academy and it’s wonderful to see the Academy being the focus for an inspirational visit by Charles Bolden. This is a very positive example of the value-added that comes from having such a broad community where we can work together for the benefit of the students.”

The event is covered in a post on the UCL Events blog, which begins:

Charlie Bolden was born in the deep south of the US, during the days of segregation and institutionalised racism. Despite this inauspicious start in life, he went on to a high-flying military career, commanded the Space Shuttle, spent 28 days in orbit and, in 2009, was made head of NASA by President Obama. He is the first African American to hold the position…

Read the full post here.

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UCL’s first Nobel Prize

By Oli Usher, on 7 October 2014

William Ramsay's Nobel Prize

William Ramsay’s Nobel Prize certificate. Photo: public domain

This week is Nobel Prize week. Prof John O’Keefe (UCL Cell & Developmental Biology) has just been announced as the winner of the 2014 Physiology or Medicine Nobel Prize for his work on positioning systems in the brain.

He joins a long list of Nobel laureates affiliated to UCL.

The very first of these was Sir William Ramsay, who won the 1904 Nobel Prize in Chemistry. Ramsay is seen as one of the fathers of chemistry at UCL, and he is responsible for the discovery of the noble gases. He also supervised two students who also went on to win Nobel Prizes themselves: Jaroslav Heyrovský and Otto Hahn.

Ramsay’s Nobel Prize certificate, pictured above, is held in UCL’s collections, along with his medal and some of the apparatus he used to carry out his research.

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Mapping the Apollo landing sites

By Oli Usher, on 29 September 2014

Lunar Orbiter Photographic DataApollo 11, which touched down in the Sea of Tranquility on 20 July 1969 was the first manned landing on the Moon. But prior to the human spaceflight project, NASA explored the Moon with robotic probes. One key element of this endeavour was the Lunar Orbiter programme, which included five spacecraft that mapped almost the entire lunar surface in 1966 and 1967. This was in part in order to identify landing sites for Apollo, but the missions also had broader scientific goals.

Shortly before the first manned landing, NASA published a catalogue of all their data from the Lunar Orbiter programme, entitled Lunar Orbiter Photographic Data. This features maps of the entire Moon, with the locations, sizes and shapes of all Lunar Orbiter photos marked on them, along with extensive technical information.

Today, missions like this work entirely online, but in those pre-internet days, the data had to exist in hard copy.

A copy of this book exists in UCL’s planetary science archives, the NASA Regional Planetary Imaging Facility. Among its pages is the mapping of the area Apollo 11 landed in, the Sea of Tranquility (Mare Tranquilitas here). This is located towards the right of this sheet, where the imaging (marked in red) is densest.

Lunar Orbiter V - Sea of Tranquility

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The LHCb experiment

By Oli Usher, on 22 September 2014

The LHCb experiment. Credit: CERN (licence)

The LHCb experiment. Credit: CERN (licence)

This week’s Picture of the Week is the LHCb (Large Hadron Collider beauty) experiment at CERN. Located in a cavern on the the French side of the Circle Line-sized cross-border particle accelerator, LHCb is as big as a house. The detector investigates why our universe is dominated by matter, rather than antimatter.

Prof Nick Brook, the newly appointed Dean of Mathematical & Physical Sciences at UCL, was the computing project leader on the LHCb experiment during the vital period leading up to first data taking. He joins joins a wide range of other CERN researchers based here.

Jon Butterworth, UCL’s head of physics, will give a public talk about his role at CERN and the discovery of the Higgs Boson on 15 October. Click here for more information.

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This picture may be reproduced providing you follow the conditions of the CERN licence.

 

Rosetta landing site chosen

By Oli Usher, on 15 September 2014

Rosetta landing site

The landing site for Philae, the lander component of the Rosetta mission, has been chosen and is marked here with a white cross. Photo credit: ESA

The Rosetta mission, which for the past decade has been on a long and convoluted journey to Comet C-G, has recently reached its destination. It is the only artificial object ever to enter orbit around a comet, and is currently circling around it at an altitude of around 30km. (The cometary nucleus itself is around 4km across.)

Part of Rosetta’s mission is to measure the properties of the plasma (electrically charged gas) that surrounds the comet. To this end, the spacecraft features a suite of five sensors built by the Rosetta Plasma Consortium, a scientific collaboration that includes UCL’s Prof Andrew Coates.

But as well as measuring the plasma around the comet, Rosetta will attempt something never achieved before: it will release a lander that, later this year, will touch down on the comet’s surface. The European Space Agency has today announced the site that the lander, known as Philae, will aim for: a spot known as Site J, pinpointed in the photo above with a white cross. The landing site was chosen as the best compromise between safety (the surface of the comet is uneven in places and could damage the probe) and scientific interest (some parts are more active than others).

Copyright: ESA images are free to use providing they are credited, do not imply endorsement by ESA, do not feature identifiable individuals, and are not used in advertising or promotional materials.

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Close encounters with fear and dread

By Oli Usher, on 8 September 2014

Cover of Phobos: Close Encounter Imaging from the Viking Orbiters

Cover of Phobos: Close Encounter Imaging from the Viking Orbiters

This week’s Picture of the Week comes from UCL’s planetary science archives, and their rich collection of early NASA space images. Many of these are not available anywhere online, and some of them are hidden behind rather unpromising covers (see above).

The Viking missions to Mars, two identical spacecraft launched a few weeks apart in 1975, are well known for making the first successful landings on the surface of the red planet. But the Viking orbiters were important too, mapping the surface of the planet and observing its moons, Phobos (fear) and Deimos (dread).

This NASA book from 1984, entitled Phobos: Close Encounter Imaging from the Viking Orbiters is a comprehensive album of the observations the programme made of Phobos, the larger of the two moons.

This picture shows a typical spread, produced during the flyby of Phobos on May 26, 1977 by Voyager Orbiter 1.

Phobos from Viking 1

Phobos from Viking 1

Although it is the larger of the two moons of Mars, Phobos is still very small, and seems likely to be an asteroid captured by Mars’ gravity, rather than a moon formed at the same time as its parent planet.

A fraction of the size of Earth’s Moon, its gravity is not strong enough to have pulled it into a sphere, leaving the irregularly-shaped object visible here.

A Russian mission to land on Phobos and return a sample to Earth, Fobos-Grunt, malfunctioned shortly after launch in November 2011 and never left Earth orbit.

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Mapping the light of the cosmos

By Oli Usher, on 1 September 2014

This image shows one possible scenario for the distribution of light in the cosmos. Photo credit: Andrew Pontzen/Fabio Governato

This image shows one possible scenario for the distribution of light in the cosmos. Photo credit: Andrew Pontzen/Fabio Governato

Figuring out what the structure of the universe is surprisingly hard. Most of the matter that makes up the cosmos is totally dark, and much of what is left is in tiny, dim galaxies that are virtually impossible to detect.

This image shows a computer simulation of one possible scenario for the large-scale distribution of light sources in the universe. The details of how light (and hence galaxies and quasars) is distributed through the cosmos is still not a settled question – in particular, the relative contributions of (faint but numerous) galaxies and (bright but rare) quasars is unknown.

A faint dwarf galaxy

(New research from UCL cosmologists published last week shows how we should be able to find out soon.)

However, astronomers know that on the largest scales, the universe is structured as a vast web made up of filaments and clusters of galaxies, gas and dark matter separated by huge, dark voids. Observational astronomy is making strides forward in mapping out these structures in gas and light, but the smallest galaxies – less than a pixel across in the image above – might never be seen directly because they are simply too faint.

A Hubble image of a nearby faint dwarf galaxy (right) shows the challenge involved in observing these objects even when they are in our galaxy’s vicinity.

These computer models are one way of trying to extrapolate from what we know to what is really there. New research from UCL now shows how we can also use future observations of gas to find out more about this elusive population of tiny galaxies.

This simulated image shows the distribution of light in an area of space over 50 million light-years across. The simulation was created by Andrew Pontzen of UCL and Fabio Governato of the University of Washington.

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Photo album from the Dark Energy Survey

By Oli Usher, on 18 August 2014

The Dark Energy Survey, which has just begun its second year of observations, is gathering data about one of the most puzzling phenomena to be discovered in the past century: that the universe is not only expanding, but is doing so at an ever faster rate. Some as yet unknown force dubbed ‘dark energy’ is driving this acceleration.

Dark energy affects the appearance and evolution of the universe on very large scales. The Dark Energy Survey aims to find out more about this phenomenon by studying measuring four key cosmological probes:

  • The number of galaxy clusters;
  • The distances to faraway supernovae;
  • The bending of light by gravitational lensing;
  • and the pattern of the distribution of galaxy clusters across the universe.

Observing these requires sharp images that can detect very distant (and hence faint) objects, and so the the images collected by the Dark Energy Camera, the survey’s workhorse, are often quite stunning.

This image of the NGC 1398 galaxy was taken with the Dark Energy Camera. This galaxy lives in the Fornax cluster, roughly 65 million light-years from Earth. It is 135,000 light-years in diameter, just slightly larger than our own Milky Way galaxy, and contains more than a billion stars. Credit: Dark Energy Survey.

This image of the NGC 1398 galaxy was taken with the Dark Energy Camera. This galaxy lives in the Fornax cluster, roughly 65 million light-years from Earth. It is 135,000 light-years in diameter, just slightly larger than our own Milky Way galaxy, and contains more than a billion stars. Credit: Dark Energy Survey.

To mark the beginning of the second year of DES’s five-year observing run, the team have published a gallery of the most attractive images from the first year of operation, including the image of galaxy NGC 1398, pictured above. The complete the gallery is at the end of this post and in the faculty Flickr gallery.

UCL is deeply involved in DES, and Prof Ofer Lahav, Vice-Dean (Research) of Mathematical & Physical Sciences, is chair of the DES UK board and co-chair of the DES international science committee.

More information on UCL’s involvement in the DES science programme is available in an article on the UCL news pages.

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Copyright: Dark Energy Survey photos are free to use providing they are credited to the Dark Energy Survey. Any queries on reuse should be sent to Fermilab Visual Media Services at vismedsr@fnal.gov.

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