A peculiar fact  

It's a peculiar fact that if a particular building had not collapsed on 21st July 1801, we may not know as much as we do today about the chemical composition of stars. It all began with glass, and a small boy whose father was a glass maker. The boy's name was Joseph Von Fraunhofer, and and he worked with his father after only a very limited school education. His father was very poor.

Glass making was a skilled but not profitable business, and education cost money. When Joseph was  ten years old he began to work with his father.

When he was about 14 years old, and his father had sadly died, he was badly treated by a company he worked for and it was during this time that the building he had found for a roof over his head actually collapsed when he was in it. A compensatory gift of money enabled him to escape his life of poverty and work eventually for a much better and reputable company for whom he made lenses of the most excellent quality.

All lenses act to lesser and greater degrees like prisms. Sir Isaac Newton had in 1666, just over a hundred years prior to Joseph's birth, discovered that prisms split light into the colours of a rainbow. Astronomers found lenses which acted like prisms to be a great nuisance as it distorted the clarity of the image. Joseph devised a way to reduce this nuisance.

Joseph placed each lens between himself and a candle to check and measure the prism effect of each lens he made.

Except one day he didn't.

He used the Sun instead.

What he saw, is how we know what a star is made of. Joseph didn't know that at the time. In fact he never knew this. He died before anyone knew this. Yet his work paved the way to one of the most outstanding discoveries. What did he see? He saw a series of dark lines.

This was Joseph  Fraunhofer's original drawing of what he saw when he placed one of his lenses in between him and the Sun for the first time (Credit NASA).

A series of dark lines appeared to be imposed on the continuous spectrum of colours. The famous German stamp that showed Fraunhofer's orginal
drawing is shown on the right. (credit NASA)

Fraunhofer managed to resolve 574 of these lines which appeared in the spectrum of the Sun. The question was, what were they? 

This was one jigsaw puzzle that would take another 30 to 40 years to complete.

Here are some of the pieces that young Fraunhofer now in his early 20s discovered;
(remember he never looked directly AT the Sun because to do so is dangerous and would cause instant blindness for life)

1) When viewing the light from the Moon and planets, he found the same pattern of dark lines as he found when viewing the Sun.

2) When viewing the light from the star Sirius he found there was a different pattern of dark lines.

3) When heating up certain gases and viewing light through these gases when the gas reached a certain temperature, a dark line pattern appeared similar to some of the dark line patterns he observed in the Sun's and Sirius's spectrum.

Fraunhofer worked out an estimate of the wavelengths at which all these dark lines appeared in the spectrum of the Sun. He didn't know what they were, or what caused them, but he determined to observe in as much detail as he possibly could.

38 years later, in 1859,  Gustaf Kirchhoff realised the extraordinary truth: that these dark lines were what we now know of as 'absorption lines' The light of the Sun has to pass through the 'atmosphere' of the Sun and as it passes through the gases which make up the atmosphere, some of the light is absorbed by these gases. Each gas absorbs light at very specific wavelengths. So each gas can be identified by its position in the spectrum.

The light emitted is emitted from the photosphere part of the Sun through the rest of the photosphere and then through the chromosphere. These are parts of the Sun which could loosely be called the surface of the Sun, but in fact it isn't really a surface at all, but more a continual plasma of gaseous material which light is emitted from and passes through.

The elements identified in the photosphere and chromosphere are thought (by a complex series of physics equations) to be pretty similar to the make up of the rest of the Sun except for the core (that's for another blog).

(A note on wavelengths; the longer wavelengths of light correspond to the red end of the spectrum. The shorter wavelengths of light correspond to the bluer end of the spectrum.)

This truth was mind blowing, as mind blowing as the realisation 300 years previously, that the Earth went around the Sun.

This astonishing truth as to the cause of absorption lines opened the door for a whole new scientific study, the physics of the stars, which we now know as Astrophysics. This meant that for every star a spectrum could be produced which would tell us exactly what elements are in the star.

Helium
In 1870 a man called Lockyer found an absorbtion line that he could not identify with any known element on Earth. So he concluded that it was an element and a gas that was only found in the Sun's composition. He named it Helium, (Helios was the Greek for Sun, hence the heliocentric theory) 50 years later the same element was discovered on Earth.

Doppler effect
Not only was this a revolutionary discovery, but there was more to come to astound. Astronomers noticed that when viewing the spectrum of the edge or limbs of the Sun the spectrum lines were shifted along either to the left of right of their original positions when viewing the centre of the Sun.

Realisation dawned that what was happening was the same thing that happened to sound waves when a vehicle passes by; the wave is shortened when it is coming towards you and stretched when going away from you. The same is true of light waves, and what the shift in absorption lines meant was that the one limb of the Sun was travelling away and the other towards the observer. This meant that the rotation of the Sun could be measured. Another whole new vista had opened to astronomers.

Radial velocities
In the early 1900s Edwin Hubble studied the spectra of distance galaxies as part of the ongoing debate as to what galaxies were. He noticed that some of them had huge (compared with the Sun's shifted spectra) shifts of their spectra, which he called redshifts because the shifts were towards the red part of the spectrum. He suggested that the interpretation was that these galaxies were speeding away from us at enormous speeds and some as large as one tenth the speed of light.

The day the building collapsed started a chain reaction of discovery leading to,

1. Each absorption line corresponded with specific elements
2. The ability to be able to identify what the Sun's composition was.
3. A new element helium being discovered first in the Sun.
4. To be able to determine the rotation speed of the Sun.
5. To be able to determine the rotation speeds of nearby galaxies and the speed at which distant galaxies were travelling away from us, and therefor the distance of them.
6. The main elements in the composition of galaxies
7. That our Galaxy is an island universe and that there are at least 100 billion other galaxies each with an avarage of between 100 - 300 billion stars.

Joseph Fraunhofer did not live long enough to know all these consequences of his work, yet he took the skill that was in his hand and worked as hard as he could, producing such accurate results that others could build on and work with.

A young lad, with such unassuming beginnings as he had, in poverty with virtually no official education eventually led to tremendous discoveries which began with his very specific glass making skills, an unstable old building, and his decision one day to use the Sun instead of a candle to produce a spectrum.
















http://www.astronomygcse.co.uk/AstroGCSE/Unit2/Fraunhofer.htm

http://www.madehow.com/inventorbios/43/Joseph-von-Fraunhofer.html

Space, the final frontier

March 3rd 1972 was a day that passed by like any other for most people. yet it was a day that changed space exploration forever, altered our world view and shaped all future space missions more than any other day in history has so far ever done.


It was though, a day that was overshadowed by the Apollo missions, because Apollo 15 (launched 26th July 1971) was the first mission to take a lunar rover to the Moon with them, and the glow of that outstanding achievement outshone all others especially with Apollo 16 being eagerly anticipated and gearing up for launch on 16th April 1972. Not surprising then that the associated media overlooked the plucky little Pioneer 10 craft, whose launch date was nestled quietly and inconspicuously between those two missions just 6 weeks before Apollo 16 was due to launch.


That day, on the 3rd March, something the size of an old fashioned widescreen tv (well if you count all the booms and antennae the length would be about the length of a family sized car) was launched from Cape Canaveral on an Atlas-Centaur vehicle. It reached a speed of more than 30,000mph pretty soon after launch. This was the fastest speed that any spacecraft had ever attained.


11 hours later it reached the Moon.


12 weeks later it flew past Mars.


3 months later it reached the Asteroid Belt and began it's journey through the most populated with rocks place in the entire Solar System. Yet just to put that in perspective, over populated with its fair share of rocks it may be but the course that NASA had given the little Pioneer was to get no closer than five and a half million miles to one of those rocky bodies to ensure its safety as it passed through.


Pioneer 10 was the very first spacecraft to fly through the Asteroid Belt and through this 'gate to the outer planets'. It was the fastest vehicle that had at that time ever been made and it was speeding up. It was speeding up because the planet it was first heading for was giving it a huge gravitational welcome like no other planet in our Solar System can. Jupiter, its first destination after the Asteroid Belt, was pulling it in until little Pioneer was flying at around 80,000 mph.


It finally reached Jupiter or, as is more technically described, reached its closest approach on the 4th December 1973. Travelling at around just over 81,000 mph it passed by Jupiter around 81,000 miles above the top layer of clouds. Here is the first series of photos taken from Pioneer as it approached Jupiter. It actually began taking photos of Jupiter from the 6th November 1973, the first ever taken from so far out in space.

As it travelled 'behind' Jupiter, the planet became a crescent which gradually faded away back into the inky backcloth of sky as Pioneer left it behind forever.


In amongst all the many and varied sets of data Pioneer sent back to Earth was something extremely surprising. Even more surprising is that the vast majority of people still don't know.


Pioneer told us, that all the evidence from studying its magnetosphere leads to one conclusion, that Jupiter is not so much a gas giant, as a liquid giant! This was a totally unexpected and extraordinary discovery. Even more shocking is that this liquid is a type of liquid that does not exist on Earth, and we have no idea what it might look like! Astronomers are still getting their heads around that one! Perhaps that's why they are still referred to as the gas giants and not the liquid giants.


Pioneer achieved many firsts, first to go as fast as it did, first to pass through the Asteroid Belt, first to reach Jupiter, first to detect atoms of helium in the space between the planets, first to detect sodium and aluminium ions in the solar wind, first to confirm a long held theory that Jupiter had a heat source that was and is causing the great planet to emit more heat than it receives from the Sun, first to pass and travel further than the orbits of all the planets in our Solar System, and there were many more firsts which you can read up about on the NASA website, http://www.nasa.gov/centers/ames/missions/archive/pioneer.html


It  passed Jupiter, after taking hundreds of photos, and then went on to pass by the orbits of Saturn, Uranus, Neptune and Pluto (at that time still regarded as a planet) and became the first human made machine to head out into the great outdoors of the Solar System and reach for the Interstellar medium. Pioneer 10's mission officially came to a close on the 31st March 1997,  but NASA followed its progress for another 6 years as part of researching the technology for communicating with spacecraft and probes at great distances in preparation for future missions.


On 23rd January 2003, Pioneer metaphorically waved goodbye to us as NASA received its final detectable signal. We may not hear from it any more, but as far as we know it continues on it's way towards the Interstellar medium and then on towards the star Aldebaran, the eye of Taurus the Bull. It should only take a couple of million years or so to get there.


One more thing, when it does reach the Aldebaranians they'll know we sent it because bolted on to the Pioneer 10 (and 11)'s small frame is a small gold-coloured plaque with a nice picture of a man and a woman and of course a map of how to get to Earth in case, I imagine, they fancy a nice cuppa and a sandwich one day if they happen to be passing.

The Pioneering Welshman

Isaac Roberts was born in 1829, in the village of Groes, North Wales

Up until the mid to late 1800s, no one knew anything about galaxies or further than the furthest star which Galileo and those who followed after could see in their telescopes. The known Universe was all that could be seen.

There were however, some strange things in the night sky. in 1730 Charles Messier was born, and soon became famous for hunting comets. He observed many fuzzy looking objects that at first, he thought were comets, until he saw that they did not move. Annoyed, he discarded these fuzzy unknowns, listing them so that if anyone came across them again they would know they were not comets. This listing eventually became known as the Messier Catalogue, one of the most important in modern astronomy. Messier died in 1815, just 14 years before Isaac Roberts was born, leaving a legacy of celestial objects which would set the scene for the next massive mind numbing astronomical revolution.

These fuzzy objects grew in number as more astronomers acquired telescopes. What were they? A welsh man called Isaac Roberts, fascinated by the heavens, and one of the cleverest engineers of the time, began to develop in 1883 a way of taking photographs of celestial objects which allowed these fuzzy objects to be viewed in detail. He did something no one had done before, found a way of taking long exposure photographs of extremely faint celestial objects.

Here is his most well known photograph of the Adromeda Nebula M31. The first long exposed photo of M31 ever taken was by Roberts in 1887 from his own observatory in Sussex.

Messier had in 1764 catalogued the Andromeda Nebula as M31. 

Taken from A Selection of Photographs of Stars, Star-clusters and Nebulae, Volume II,

The Universal Press, London, 1899.

As Roberts looked at this photo, what did he think? We will never know, yet we know he mused over it enough to wonder at what exactly it was he had in front of him. The fuzzy object now huge in the frame, swirling mass of what? gas? particles?  Did he ever think "could they be stars?" the current view is that he thought it was a nebula within our Galaxy and a new 'solar system' being formed.

In the mid 1920s Edwin Hubble along with several others finally concluded without any doubt the mind blowing realisation that this was, in fact, completely outside our Galaxy, and that our Galaxy was, itself, an island universe - one of we now know at the very least one hundred billion!

Isaac Roberts died on July 27th 1904, 21 years before this new astronomical revolution. Yet his contribution began the journey to this discovery.

By the mid 1920s then, the Universe had just increased in size to a mind meltingly unimaginable space. Our Galaxy - one of billions, each containing around a hundred to three hundred billion stars. This was a much greater shock in some ways than the shock of Earth orbiting the Sun! Yet the really strange thing is and was that this information never really filtered down to the general public.

The mid 1920s is not even one hundred years ago!