Up, up and away

This artist"â„¢s concept shows a glowing patch of ultraviolet light near Saturn"â„¢s north pole that occurs at the 'footprint' of the magnetic connection between Saturn and its moon, Enceladus.
Image credit: Nasa/JPL
Date:11 May 2011 Author: Alan Duggan Tags:,

This question came up in a quiz the other day, so I thought I would run it past PM’s astonishingly clever audience: ‘Can you name at least five classic rock songs about space travel?’ (See the bottom of this blog for some answers.)

Still on the subject of space and music, some of you may recall a Nasa report from 2003 in which British astronomers were reported to have discovered a “singing” black hole in a distant cluster of galaxies. In the process of listening in, the astronomers not only heard the lowest sound waves from an object in the Universe ever detected by humans, but also discovered an important clue about the formation of galaxy clusters – the largest structures in the cosmos.

Andrew Fabian and his colleagues at the Institute of Astronomy in Cambridge, England, made their discovery using Nasa’s Chandra X-ray Observatory, an orbiting X-ray telescope that sees the Universe in X-ray light just as the Hubble Space Telescope sees it in visible light. The black hole is located in the centre of a galaxy amid a group of thousands of galaxies collectively called the Perseus Cluster, about 250 million light years from Earth (which means it took the light from these galaxies 250 million years to reach us). The sound waves coming from it are in the form of a single note, so it’s a drone rather than a song.

Reported Nasa: “Using the piano keyboard’s middle C note as a reference point for the middle of the piano key music range, Fabian’s team determined the note is a B-flat. On a piano, the B-flat nearest middle C is located midway between 1/8th and 2/8th of an octave away. In musical terminology, this B flat is 1-1/2 steps from middle C. The Perseus cluster black hole’s B-flat, by contrast, is 57 octaves below middle C, or one million, billion times lower than the lowest sound audible to the human ear. In terms of frequency (the time it takes a single sound wave to pass by), the lowest sounds a person can hear is 1/20th of a second. The Perseus black hole’s sound waves have a frequency of 10 million years!

Eight years on, we hear of a new number from the cosmic sound factory, this one in the form of an electrical connection between Saturn and one of its moons, Enceladus. The data collected by Nasa’s Cassini spacecraft is enabling scientists to improve their understanding of the complex web of interaction between the planet and its numerous moons. The results of the data analysis are published in the journals Nature and Geophysical Research Letters.

Scientists previously theorised an electrical circuit should exist at Saturn. After analysing data that Cassini collected in 2008, scientists saw a glowing patch of ultraviolet light emissions near Saturn’s north pole that marked the presence of a circuit, even though the moon is 240 000 km from the planet. The patch occurs at the end of a magnetic field line connecting Saturn and its moon, Enceladus. The area, known as an auroral footprint, is the spot where energetic electrons dive into the planet’s atmosphere, following magnetic field lines that arc between the planet’s north and south polar regions.

“The footprint discovery at Saturn is one of the most important fields and particle revelations from Cassini and ultimately may help us understand Saturn's strange magnetic field,” says Marcia Burton, a Cassini fields and particles scientist at Nasa’s Jet Propulsion Laboratory in Pasadena, California. “It gives us the first visual connection between Saturn and one of its moons.”

Source: Nasa/JPL

Watch a video demonstrating the hiss-like radio noise generated by electrons moving along magnetic field lines from the Saturnian moon Enceladus to a glowing patch of ultraviolet light on Saturn.

Quiz answers:
Countdown – Rush; Space Oddity – David Bowie; Rocket Man – Elton John; Cygnus X-1 – Rush; Interstellar Overdrive – Pink Floyd; Into The Void – Black Sabbath; 2000 Light Years From Home – The Rolling Stones; Children Of The Sun – Billy Thorpe; Walking On The Moon – The Police; Astronomy Domine – Pink Floyd; Space Baby – The Tubes; The Final Countdown – Europe.

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