Comet 67P/Churyumov-Gerasimenko on 20 November 2014

The Nucleus of Comet 67P/Churyumov-Gerasimenko on 20 November 2014

• Title Comet on 20 November – NavCam
• Released 26/11/2014 6:00 pm
• Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
• Description This mosaic comprises four individual NAVCAM images taken from 30.8 km from the centre of Comet 67P/Churyumov-Gerasimenko on 20 November 2014. The image resolution is 2.6 m/pixel and thus each original 1024 x 1024 pixel frame measured 2.7 km across. The mosaic has been slightly rescaled, rotated, and cropped, and measures roughly 4.2 x 5.0 km.
  The four individual images making up the mosaic are available via the blog: Cometwatch - 20 November
  

This week I will be sixty-five years old.  I was eight years old when I first took an interest in astronomy. In those far off days the idea of sending a robotic surveyor millions of miles and years traveling through the solar system, of placing it in orbit around the nucleus of a comet and landing a probe on the surface would have at best been considered science fiction and at worst been ridiculed as preposterous.  How lucky am I to have lived through a time of accelerating scientific development.  How proud am I of the European Space Agency in achieving this amazing scientific feat!  How pleased am I to have, in some small way and through the payment of taxes, sponsored this intellectual voyage of discovery!  How proud am I to be European! How determined am I to live long enough to witness the demise of all ignorant, xenophobic, extreme and inward looking political associations which act to destroy the unity of humanity and turn Europe into a mosaic of nationalistic enclaves!  Toot and I do not wish to return to 1950, by comparison with 2014, this decade   was crap! Toot and I know because we lived through it. We were economically poorer, public health was lower, Television was in black and white and life was generally grey and monotonous.  Joining Europe and welcoming immigrants to our islands have increased our nation's cultural diversity, our prosperity and our quality of life.  Investing our common and collective wealth in scientific and technological exploration has been both spiritually  and economically life enhancing.  So Nigel and all others like you,  if you want something different you are going to have to achieve it without Toot and me because we like it as is not as was!   AND........ ESA and NASA keep looking for evidence of intelligent life out in space because its getting harder to find it down here on earth!

Thank you ESA and Rosetta for this photograph.  A tremendous scientific feat  and a wonderful gift for my birthday.

Plato

Two versions of the same Lunar photograph that I captured from our backyard through my 127mm refractor using the video format on my Canon 600D DSLR. The version on the right has an enhanced colour saturation which highlights the changes in the reflection of sunlight from a range of minerals in the different rocks that makeup the Lunar surface.

Image of the Crater Plato taken from Lunar Orbiter 4.

My image shows the crater Plato, center left, and the 'Alpine valley', the broad stripe slightly above and to its right.

Plato is the lava filled impact crater on the Moon, located on the north eastern shore of the Mare Imbrium  and at the western end of the Montes Alpes mountain chain. To the south is a smaller chain of mountains named Montes Teneriffe  and to the north lies the wide sweep of Mare Frigoris.  Plato was created approximately 3.84 billion years ago and only just post-dates the absolutely massive impact which created Mare Imbrium.  Of course this Mare or 'sea' is a waterless desert of solidified lava which is either hot or very cold depending upon whether it is being bathed in sunlight or cloaked in shadow.  Inside Plato's 2 kilometre high jagged walls the crater floor has been flooded with a particularly dark lava (having a low albedo)  which makes it an obvious lunar feature when viewed from the earth with low power binoculars. There is no visible central peak but there are a number of later and small impact craterlets which can be seen in the image from Lunar Orbiter 4. Plato is basically circular but from earth and  in my image, it appears oval because of perspective foreshortening.  Over the years the crater has been the location for a number of 'transient lunar phenomena' or TLPs although these are generally considered visual affects related to changes in seeing and the angle of illumination by the sun. The crater is large and has an approximate diameter of 109 kilometres or 67.7 miles.

Although the moon has been observed and extensively studied for many years, we are still discovering new facts about it.  Recent data recorded by a number of satellites in orbit around the moon, have led astronomers and geologists to revise their views on the moon's geological activity. It is now believed that there has been volcanic activity on the moon as relatively recent as two million years and that the moons core is hotter than was originally considered.  It is believed that tidal affects caused by the earth, as the moon and the earth rotate about their common point of axis, acts to stress the moon's core and mantle and thus heat it. This is similar to the more extreme heating and volcanic activity experienced by the moon Io as the result of tidal affects created by the massive planet Jupiter.

Credits: NASA, Wikipedia and James Stuby

The Calabrian Volcanic Arc Part 2: Stromboli

Smokin' Stromboli as seen from our Easyjet

As we flew home to London Gatwick Toot took this photograph through the aeroplane window .   Stromboli is everyone's image of what a volcano should be: a smoking cone with white hot rocks and red hot lava rolling down its slopes.  Add to this its fantastic location: rising from a mineral blue sea and surrounded by sparkling black beaches of volcanic ash and water worn lava pebbles, and you have your best ever geological experience.

We arrived by boat and spent some time collecting rock samples from the beach beside the landing jetty.  Toot had a swim in the sea and was amazed at how buoyant she was.  We guessed that the sea water around Stromboli was supersaturated by volcanic minerals.

It was very easy to assess the position of high tide as it was picked out by a line white pumice stones. Pumice has such a low density it floats upon the sea water.  We both remembered a time, thirty years ago, swimming with our children and good friends Trevor and Christine in Oslo Fjord, when we first discovered that pumice floats in the sea.

Whilst I waited for Toot to emerge, like 'Botticelli's Venus', from the waves, I took some photos of the sun setting behind the smoking calderas and penned a poem in celebration of Toot's assistance in enabling my access to Etna a few days before.

 Beautiful Toot braves the 'Briny'

Rock samples from Stromboli

The teacher and her triskelion man 

The sun too bright to resolve or cursorily scan

Climbs sleepy from its nocturnal seabed

And waking too, the teacher and her triskelion man

Begin their ascent in search of yellow sulphur and chimera red

Traveling first on Babel's bus and then by suspended wire

The partners in adventure, life, love and time

Mark falling barometric pressure and summer's last breath

In pursuit of internal and external seismic fire

Side by side they enter a basalt new made land

A moonscape of twisted lava and calderas

They look into ash cone's fiery eye and back in time

As Orpheus once did for Eurydice

George Roberts

White hot rocks and lava skitter and slide down Stromboli's slopes to the sea

Sunset over the Stromboli's smoking Calderas

Stromboli at dusk as photographed from the boat,  
dusk suddenly renders the red hot lava visible.

As it gets darker the brightness of the 
lava streams becomes more pronounced

The river Phlegethon

A fiery cascade from overflowing caldera

The Calabrian Volcanic Arc Part 1: Etna

Geological memories of our recent October 2014 holiday in Sicily. Did the earth move for you Toot?
Without my redoubtable partner to hold my hand  and help me climb, I would not have made it to the top, thanks Toot!

Toot took this fantastic photograph of Etna through the window of the Easyjet plane, just after we left from Catania airport in Sicily, on our return journey to London Gatwick.

Etna is Europe's highest volcano and is one of the most active stratovolcanoes on the planet earth. For more information follow the link:
http://en.wikipedia.org/wiki/Mount_Etna

Etna - looking down from the rim of a cinder cone into an active fumarole. The main crater cones can be seen in the distance and at increased elevation.   Ash and gas clouds are visible over the main active summit craters and the upper slopes are tinged yellow with sulphur. When the wind direction changed, sulphurous gas was blown our way and burned acid in our throats.

Maps of Etna at various scales showing the location (yellow circle) in which the preceding photograph was taken and the lava samples were collected

This rock was taken from the crater rim, just about where the people can be seen in the above photograph (the group on the right). Toot found it in a hollow which was actively gassing out. The yellow, presumably sulphur and the red presumably iron were probably the result of the gas depositing the minerals upon the cinder. The rock itself is of medium density, lighter than the sample we collected from a nearby lava flow but heavier than the pumice we subsequently collected from the beach on Stromboli. Close inspection with a magnifying eyepiece reveals small gas vesicles and a glassy crystalline crust of yellow, red and white minerals.




This predominantly red sample was collected close to the active fumarole you can see smoking in the photograph. Our guide told us that in August this vent had suddenly become active  and consequently he had had to lead an emergency evacuation from the Volcano! So this rock is probably no more than 8 weeks old! It is about the same density as the other sample but much redder and with larger gas vesicles. Inspection with an eyepiece reveals one or two very small glassy mineral crystals.

Close up of the active fumarole. I felt quite nervous taking this photograph (Toot was a lot braver than me!) The sound affects are quite scary with rocks and ash constantly sliding away to oblivion, rattling and tinkling as they roll down the unstable ash slopes to be lost in the smoke and fire forever.

For an excellent downloadable presentation, relating to Volcanoes and volcanic rocks generally and Etna and its lava particularly, follow the link:

http://web.pdx.edu/~jjackson/Etna.pdf

This image, looking towards the main summit craters, shows the lava field behind the active fumarole. We sat and ate our sandwiches here and watched as puffs of smoke issued sporadically from voids in and between the piled up and twisted lava boulders. Our lunch was taken at approximately 3000 metres above sea-level. The distant crater rims are about 300 metres higher and change with each successive major eruption or quake.

We laughed when we noticed that the low air pressure had caused our packets of  crisps to inflate like balloons!

This sample of lava was taken from the lava field shown in the above photograph. In colour the lava is dark grey with a blue-green highlight. It has been contorted into a bewildering number of random shapes which have fused together to create an alien landscape. The lava is sharp and both dangerous and impossible to walk upon in safety.

The rock is much denser and has smaller and less frequent gas vesicles. Close inspection with an eyepiece reveals a number of small glassy white quartz like crystals.

Our view of the Summit Craters wreathed in smoke at 10.30 am. on the13th October 2014

Smoke from the fumarole blocks the sunlight as tourists march along the crater rim.

Etna: major eruption (2001?) as seen from the International Space Station credit Reid Wiseman/NASA

 Credits: Wikipedia, NASA, The Earth Institute Columbia University, Portland University and Easyjet