I opened this website when we retired to France (2005) – just to keep in touch with family and friends. It has changed over the last 16 years, as most things would. It is now more of a mélange of astronomy and cosmology than a diary of life in France. I follow my interests in cosmology and interplanetary exploration and the general notes below are just my untidy memoranda for reference.
March 2022:
Well we are double vaccinated and are free to associate again. And how things have changed.
Perseverance has spent over a year on Mars and Ingenuity Helicopter has established several firsts despite some loss of lift in the (summer) months – atmospheric pressure is low.
James Webb (IR) telescope has arrived at Lagrange point L2 which is an heliocentric point of stability between Sun, Moon and Earth and at a distance of ~ a million miles from Earth: there is 
no going back to adjust optics (like Hubble)
Here’s JWST
and its builders just for scale
ASTRONOMY CORNER (HISTORIC NOTES)
PERSEVERANCE LANDING (Feb 18th 2021)
Pic from skycrane, data loaded down cable to rover, and then transmitted via Mars orbiter to Earth. Already an historic picture.
SPACEX STARSHIP this is the first picture released of SN8 complete with nosecone and fins. October 2020, already an historic picture.
Missions to Venus (courtesy Michael Cowell – Planetary Society)
Click to enlarge
SpaceX Dragon landing
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Dragon’s Flight Screens (below)
just compare this with Shuttle (but the Shuttle was also a glider)
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SpaceX’s “Starhopper” 
First flight testing Raptor Engine
This could be likened to living at the time of the Wright Brothers.
Elon Musk’s Starlink launched May 2019
click on pic
Is this is the end of astronomy as we know it..?
(I remember saying much the same on July 20th 1979…..)
click on colour below to refer to Wikipedia
the Space Shuttle
The first orbiter, Enterprise, was built in 1976, used in Approach and Landing Tests and had no orbital capability. Four fully operational orbiters were initially built: Columbia, Challenger, Discovery, and Atlantis. Of these, two were lost in mission accidents: Challenger in 1986 and Columbia in 2003, with a total of fourteen astronauts killed. A fifth operational (and sixth in total) orbiter, Endeavour, was built in 1991 to replace Challenger. The Space Shuttle was retired from service upon the conclusion of Atlantis‘s final flight on July 21, 2011. The U.S. has since relied on the Russian Soyuz spacecraft to transport astronauts to the International Space Station, pending the Commercial Crew Development and Space Launch System programs on schedule for first flights in 2019 and 2020. ( Wiki)
the International Space Station
The International Space Station (ISS) is a space station, or a habitable artificial satellite, in low Earth orbit. Its first component was launched into orbit in 1998, with the first long-term residents arriving in November 2000. It has been inhabited continuously since. The last pressurised module was fitted in 2011, and an experimental inflatable space habitat was added in 2016. The station is expected to operate until 2030
Development and assembly of the station continues, with several new elements scheduled for launch in 2020. The ISS is the largest human-made body in low Earth orbit and can often be seen with the naked eye from Earth. The ISS consists of pressurised habitation modules, structural trusses, solar arrays, radiators, docking ports, experiment bays and robotic arms. ISS components have been launched by Russian Proton and Soyuz rockets and American Space Shuttle. (Wiki)
ULTIMA THULE
Noted May 2019
The New Horizons spacecraft is now 4.1 billion miles (6.6 billion kilometers) from Earth, operating normally and speeding deeper into the Kuiper Belt at nearly 33,000 miles (53,000 kilometers) per hour.
NASA
click on pic
The Apollo Astronaunts, those who walked on the Moon: from Wikipedia
Those who orbited the Moon
Click to enlarge
GW170817
Three LIGO observatories that detected Gravitational Waves click to enlarge
current list of NASA’s “GREAT OBSERVATORIES”
1 HUBBLE SPACE TELESCOPE
launched 1990 Geocentric Perigee 540 km Visible / IR
2 FERMI LARGE AREA TELESCOPE (GAMMA RAY)
launched June 2008 Geocentric Perigee 530 km
3 CHANDRA X-RAY TELESCOPE
launched 1999 Geocentric: Highly elliptical: above earth’s radiation belts:
Perigee 14,000 km, Apogee 134,500 km
4 SPITZER IR SPACE TELESCOPE (DECOMMISSIONED May 2020 to be replaced by James Webb S.T. scheduled launch 2021)
launched 2003 Heliocentric Earth trailing: perihelion 1.003 AU
I/R (exoplanets)
5 SWIFT GAMMA RAY BURST ALERT MISSION
launched 2004 Geocentric Perigee 560 km Inclination 20.5 degrees
X-ray U/V and optical (Pulsar Search)
Hertzsprung-Russel Diagram: the stellar life line (click to enlarge)
Hertzsprung-Russell Diagram (Wikipedia)
LIGO RESULTS
NASA Missions Catch First Light from a Gravitational-Wave Event
For the first time, NASA scientists have detected light tied to a gravitational-wave event, thanks to two merging neutron stars in the galaxy NGC 4993, located about 130 million light-years from Earth.
Shortly after 8:41 a.m. EDT on Aug. 17, NASA’s Fermi Gamma-ray Space Telescope picked up a pulse of high-energy light from a powerful explosion, which was immediately reported to astronomers around the globe as a short gamma-ray burst. The scientists at the National Science Foundation’s Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves from a pair of smashing stars tied to the gamma-ray burst, encouraging astronomers to look for the aftermath of the explosion.
What was once a pipe dream is becoming old hat. Scientists with the Laser Interferometer Gravitational-Wave Observatory (LIGO) have announced their discovery of another black hole merger, revealed when the gravitational waves that were created by the cosmic consolidation changed the length of the two LIGO sites’ arms by approximately one-thousandth the width of a proton.
The newly announced event, called GW170104, squeezed and stretched LIGO’s 4-km-long arms on January 4th, during the observatory’s second observing run. The larger of the two black holes had a mass between 25 and 40 times that of the Sun; the smaller, between 13 and 25 Suns. The resulting black hole has a mass of about 50 solar masses, with a couple of solar masses carried away as gravitational radiation, the collaboration reports June 1st in Physical Review Letters.
See Gouvert Schilling’s book “Ripples in Spacetime” ISBN 9780674971660
PARKER SOLAR PROBE 31st May 2017: The mission, Solar Probe Plus,was launched in the summer of 2018. Placed in orbit within four million miles of the sun’s surface, and facing heat and radiation unlike any spacecraft in history, the spacecraft is sampling the sun’s outer atmosphere and making observations that will answer decades-old questions about the physics of how stars work. (Mercury’s orbit is about 36 million miles from Sun)
Lagrangian Points, these are islands of stability near any planetary body in the solar system (described in the sketch below by green dots within gravity contour lines.) I think you mostly understand this concept as it figured later in
my reply to a question about the Big Bang. I refer to the WMAP probe which was established at L2 to seek any evidence of isotropy in the radiation “left -over” from the Big Bang.
This artists sketch below (Wikipedia) describes the Big Bang (if that were possible)
The Wilkinson Microwave Anisotropy Probe (WMAP), originally known as the Microwave Anisotropy Probe (MAP), was a spacecraft operating from 2001 to 2010 which measured temperature differences across the sky in the cosmic microwave background (CMB) – the radiant heat remaining from the Big Bang. the probe was “stationed” at the Lagrangian point L2. The mission was developed in a joint partnership between the NASA Goddard Space Flight Center and Princeton University.[5] The WMAP spacecraft was launched on June 30, 2001 from Florida. The WMAP mission succeeded the COBE space mission and was the second medium-class (MIDEX) spacecraft in the NASA Explorers program. In 2003, MAP was renamed WMAP in honour of cosmologist David Todd Wilkinson (1935–2002),[5] who had been a member of the mission’s science team. After 9 years of operations, WMAP was switched off in 2010, following the launch of the more advanced Planck spacecraft by ESA in 2009. see Wikipedia
Who are we ?
TEAPOTES ASTRO GROUP 2017
Good Stargazing, Martin
CASSINI’S GRAND FINALE:
Saturn at solstice (L) this is close-up of Saturnian North pole – the famous hexagon shaped cloud formation. (24 May 2017)
Following these closer-than-ever encounters with the giant planet, Cassini made a final plunge into Saturn’s upper atmosphere on Sept. 15.
Latest Cassini photo of Mimas (discovered by Herschel 1789) clearly shows the Herschel crater. Mimas is about 400 km diam, orbit radius ~ 185000 kms. – just outside Saturn’s rings. and due to orbital resonances is responsible for the Encke Gap in the A ring.
GOODBYE MIMAS
6th March 2017 The TRAPPIST System of exoplanets
click on pic to enlarge This chart shows, on the top row, artist concepts of the seven planets of TRAPPIST-1 with their orbital periods, distances from their star, radii and masses as compared to those of Earth. On the bottom row, the same numbers are displayed for the bodies of our inner solar system: Mercury, Venus, Earth and Mars. The TRAPPIST-1 planets orbit their star extremely closely, with periods ranging from 1.5 to only about 20 days. This is much shorter than the period of Mercury, which orbits our sun in about 88 days.
The artist concepts show what the TRAPPIST-1 planetary system may look like, based on available data about their diameters, masses and distances from the host star. The system has been revealed through observations from NASA’s Spitzer Space Telescope and the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope, as well as other ground-based observatories. The system was named for the TRAPPIST telescope.
The seven planets of TRAPPIST-1 are all Earth-sized and terrestrial, according to research published in 2017 in the journal Nature. TRAPPIST-1 is an ultra-cool dwarf star in the constellation Aquarius, and its planets orbit very close to it.
NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at Caltech/IPAC. Caltech manages JPL for NASA.
THE TRAPPIST SYSTEM of EXOPLANETS
At about 40 light-years (235 trillion miles) from Earth, this system of planets is relatively close to us, in the constellation Aquarius. Because they are located outside of our solar system, these planets are scientifically known as exoplanets.
This exoplanet system is called TRAPPIST-1, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. In May 2016, researchers using TRAPPIST announced they had discovered three planets in the system. Assisted by several ground-based telescopes, including the European Southern Observatory’s Very Large Telescope, Spitzer confirmed the existence of two of these planets and discovered five additional ones, increasing the number of known planets in the system to seven.
Any Pics? Artists impressions only (info is based on light transmission data from long exposure on this red dwarf star.) M
17th April 2017 New Horizons in the Kuiper Belt
“This flyby will set the record for the most distant world ever explored in the history of civilization” Alan Stern, New Horizons principal investigator, Boulder, Colorado.
New Horizons will begin a new period of 157 days hibernation this week. The January 2019 MU69 flyby is the next big event for us, said Hal Weaver, New Horizon’s project scientist from APL Maryland. “In addition to MU69, (at 43.4 AUs from Earth) we plan to study more than two dozen other KBOs in the distance”
Note N.Horizons is currently 3.5 billion miles from earth and radio signals need about 5 hours and 20 minutes to reach the spacecraft. – M
February 6th 2017 JD 2457790.5
LAGRANGIAN POINTS
NASA’s has announced new DISCOVERY mission: probe LUCY (launching 2021) will be exploring Jupiter’s TROJAN asteroids specifically at the L4 and L5 points. “Because the Trojans are remnants of the primordial material that formed the outer planets, they hold clues to the history of the solar System.” Planned arrival at the trojans is August 2027. !! I’ll keep you posted.. As you may note the drawing above is for Earth’s Lagrange points, but it applies to any of the planets.
Click on pic to enlarge
December 3rd 2016 PLANET “9”
For the last ten years, while we’ve been busy cataloging other solar systems, we’ve also discovered lots of smaller bodies outside the orbit of Neptune. A few are close to Pluto in size (one, Eris, is actually more massive than Pluto), and many smaller ones. In 2014, two astronomers, Chad Trujillo and Scott Sheppard, wrote a letter to the journal Nature stating that something was, well, a bit odd about the orbits of all the small, dark bodies recently found outside the orbit of Neptune. The orbits appeared to be oddly lined up; their perihelions (the closest approach to the Sun) were almost on top of each other in a similar part of the sky, instead of being randomly distributed as one might expect.
These small bodies didn’t have the mass to line each other up that way all by themselves, so the suggestion was made that a much more massive planet might be out there –way out there, maybe 30 times farther away than Neptune, exerting a gravitational pull to shepherd these objects into similar orbits.
Brown and Batygin then added in the orbits of six more farther out objects, and not only did these things all turn out to have lined-up perihelions, their orbits turned out to be in almost the exact same plane with each other. According to the Caltech group, there was only a 0.007% probability that this could happen by chance. Something unseen, soon dubbed “Planet 9,” was tugging on these small bodies. And that something that had to be big; somewhere in the neighbourhood of ten times the mass of the Earth.
This “new” planet, if it exists, might fill in an important missing piece to our solar system. As we’ve explored worlds around other stars, we’ve noticed that the most common sort of planet out there is one we don’t seem to have in our solar system. Planets in the mass range of 5 to 10 Earth masses, sometimes called “super-Earths” or “mini-Neptunes,” (we do not yet know if such planets are more similar to a large Earth or the core of a gas planet like Neptune) substantially outnumber other planets. Where is ours? Maybe we’ve finally found it in “Planet 9”, perhaps flung out into a ludicrously distant orbit by a past encounter with another massive planet. Just waiting for us to finally include into our family of planets.
(Sky & Telescope)
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18th November 2016 Microsats:
We spoke about the new “cube sats” at our last meeting, well here’s an artists impression of a batch of NASA micro satellites in low earth orbit. These are for meteorological (hurricane watch) purposes. As far as I can make out they are the size of a loaf of bread and are positioned in groups, “constellations” to obtain stereo images. And no, they don’t fly, the “wings” are solar panels which unfold after launch. More later. M
click on pic to enlarge
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5th November 2016
James Webb Space Telescope.
named after the late NASA administrator who saw the Apollo program through to the Moon landing in 1969, and drove the funding for the original Hubble Space Telescope.
The JWST is the replacement for the Hubble ST and will be placed in a heliocentric orbit at a Lagrange point (L 2). The launch date scheduled for 2018, but still awaiting 2020 see pic below
Mirror being prepared for launch
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25th March 2017 MARS CURIOSITY ROVER
Recent evidence of further damage to Curiosity’s aluminium wheels:
A routine check of the aluminum wheels on NASA’s Curiosity Mars rover has found two small breaks on the rover’s left middle wheel—the latest sign of wear and tear as the rover continues its journey, now approaching the 10-mile (16 kilometer) mark.
The mission’s first and second breaks in raised treads, called grousers, appeared in a March 19 image check of the wheels, documenting that these breaks occurred after the last check, on Jan. 27.
“All six wheels have more than enough working lifespan remaining to get the vehicle to all destinations planned for the mission,” said Curiosity Project Manager Jim Erickson at NASA’s Jet Propulsion Laboratory, Pasadena, California. “While not unexpected, this damage is the first sign that the left middle wheel is nearing a wheel-wear milestone,”
22nd November 2016 MARS – NASA’s Curiosity Rover
This is a recent picture from Curiosity of strata at Murray Butes, (Mount Sharp – Gale Crater) This is wind blown erosion on billion year old sediments. just amazing.
click on pic to enlarge
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January 9th 2017
Cassini Begins Epic Final Year at Saturn
Diagram released by NASA showing new orbit threading between Saturn and his rings. Close up pictures expected soon.
click on pic
After more than 12 years studying Saturn, its rings and moons, NASA’s Cassini spacecraft has entered the final year of its epic voyage. The conclusion of the historic scientific odyssey is planned for September 2017, but not before the spacecraft completes a daring two-part endgame.
This is recent photo of Saturn’s north polar region showing the polar hexagon.
Beginning on November 30, Cassini’s orbit will send the spacecraft just past the outer edge of the main rings. These orbits, a series of 20, are called the F-ring orbits. During these weekly orbits, Cassini will approach to within 4,850 miles (7,800 kilometers) of the center of the narrow F ring, with its peculiar kinked and braided structure.
JUPITER AND JUNO 2017 _____________________________________________________________________________ Juno is now orbiting Jupiter with period of 53 days, The last pass was May 18th, The next pass, which takes it directly over the Great Red spot, will occur on July 11th. Data download takes about 1.5 days.
JUNO- Close encounters with JUPITER
2nd April 2017
South Pole of Jupiter:
On right: Jupiter’s “little red spot” close up – the pale cyclone on the lower part of the photograph. Amazing details.
Close up showing GRS and regular cyclonic clouds. Juno pass January 2017
Close up of Southern cloud patterns :
(Oct 24th) JunoCam image below click on pic to enlarge
JUPITER POLE SHOT released May 26th 2017
Juno’s close up of Jupiter’s South Pole 18th May 2017
Redefining Juno’s Orbital period. May 2017
Juno is now orbiting Jupiter with period of 53 days, The last pass was May 18th, The next pass “flying” over the Great Red spot, will occur on July 11th. Data download takes about 1.5 days.
This is one of the first shots sent back by Juno on 27th Aug. 2016 It shows Aurora at the South Pole of Jupiter. Below right is shot of North Pole as Juno headed around from N to S.
Martin
click to enlarge
4th July 2016 JD 245 7573.5
Here’s one of NASA’s excellent recent photographs of planet Jupiter. Note the aurora is offset from apparent axis of rotation. Magnetic pole is clearly tilted Sunward. M
click on pic to enlarge
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27th June 2016 JD 245 7566.5
just setting up for discussion on the 8th July, I thought you may like to see this representation of “all” the satellites orbiting earth right now. M
more later…
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19th June 2016 Recent Panorama from Curiosity JD 245 7558.5
click to enlarge, and again.
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10th June 2016 Largest Stars to date.
This came up this morning at Teapotes Astro Group: I think this diagram helps to capture the concept of these enormous red giant stars. M
The following is a comparison of sizes, starting with our planets, (row 1 and 2) and then a comparison of stars, starting with our Sun (third in row 3) and by the time you get to row 6, the real giants, you need some figures. The Red Giant Betelgeuse is ~1000 X Solar diameter, while the largest to date is UY Scuti which is ~3,400 X Solar diameter. (not shown in diagram). Scutum (the shield) is just N of Sagiittarius, at declination -10 deg.
just click on pic to enlarge
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21st May 2016 Asteroid Sampling
See
www.youtube.com/watch?v=aYmgc9XL_Vs
Launch of First U.S. Spacecraft to Sample Asteroid Set for September, NASA Media
Artist’s conception of the OSIRIS-REx spacecraft at asteroid Bennu
NASA has announced the September launch of the first U.S. mission to sample an asteroid: NASA’s Origins, Spectral Interpretation, Resource Identification, Security – Regolith Explorer (OSIRIS-REx)
This spacecraft will travel to and collect surface material from the asteroid 101955 Bennu, and return it to Earth for study by 2023.
OSIRIS-REx is scheduled to launch aboard a United Launch Alliance Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station Sept. 8. The two-hour launch window opens at 7:05 p.m. EDT. (NASA). and why is this important ….read on
(from Wikipedia) Possible Earth impact
On average, an asteroid with a diameter of 500 m (1,600 ft; 0.31 mi) can be expected to impact Earth about every 130,000 years or so. A 2010 dynamical study by Andrea Milani and collaborators predicted a series of eight potential Earth impacts by Bennu between 2169 and 2199. The cumulative probability of impact is dependent on physical properties of Bennu that were poorly known at the time, but was not found to exceed 0.07% for all eight encounters. The authors recognised that an accurate assessment of 101955 Bennu’s probability of Earth impact would require a detailed shape model and additional observations (either from the ground or from spacecraft visiting the object) to determine the magnitude and direction of the Yarkovsky effect.
After the publication of the shape model and astrometry based on radar observations obtained in 1999, 2005, and 2011, it was possible to estimate the Yarkovsky acceleration and to revise the impact assessment. The current (as of 2014) best estimate of the impact probability is a cumulative probability of 0.037% in the interval 2175 to 2196. This corresponds to a score on the Palermo scale of −1.70. 101955 Bennu has been considered a few times as the target of spacecraft missions due to the low Δv required to reach it from Earth orbit. OSIRIS-REx mission of NASA’s New Frontiers Program is planned to launch in 2016, reach 101955 Bennu in 2019 and return samples to Earth in 2023.
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6th May 2016 Ref Mars, there is an interesting film on youtube on the difficulty of Funding a Mars expedition. Enter “The Mars Underground” filmed over the past ten years, and with some interesting photoshop clips. It’s about an hour long.
Worth watching at https://youtu.be/T2YLJdl8oB8 copy and paste
23rd April 2016 Mars JD 245 7502.5
Every 2.3 years planet Earth passes Mars (this is the Earth-Mars Synodic period) Since the orbits of Earth and Mars are elliptical, their distance apart can vary, however, next month we get to be our closest to Mars since 2005. click on pic to enlarge
Mars is closest to Earth (0.5 AU or 4.2 light minutes distance ) on Monday 30th May, when its apparent equatorial diameter reaches 18.6 arcsecs (from 16 secs on first of month) It’s about 10 years since Mars has appeared this size. (Note the apparent Solar diam is about 32 arc minutes – half a degree) So Mars will still remain rather small, but worth while locating with a small telescope. Where to look – Mars, Saturn and Antares make a fascinating triangle of red and gold “stars” in the South West morning sky – before sunrise.
The above NASA view beats that from my backyard telescope. It shows the north polar cap (mostly solid CO2 ) and south of the equator the Valles Marinas (named after Mariner probe of ’69.) It is a clearly visible cleft, deeper than the Grand Canyon. You can also make out three volcanos in line to the left. And on the far left limb is Olympus Mons, the highest mountain in the solar system. The diameter of Mars is around half that of Earth.
Good Stargazing
Martin
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16th April 2016 Space Station JD 245 7494.5
This is BEAM (Bigelow Expandable Module) which is making news at the moment: You can see the large blow up container on test against possible micrometeorites. The Bigelow Company is said to be designing “Space Hotels” using such technology. 
So let’s look at the Bigelow site to see what’s on the ‘drawing board’ : plenty of ideas
Bigelow Aerospace is an American space technology startup company, based in North Las Vegas, Nevada that manufactures and develops expandable space station modules.
Proposed Moonstation (left) and Comfortable voyaging capsule (above).
Good stargazing, Martin
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April 11th 2016 International Space Station JD 245 7489.5
The U.S. SpaceX Dragon commercial cargo craft arrived at the International Space Station April 10, two days after its launch from the Cape Canaveral Air Force Station, Florida Loaded with some three and a half tons of supplies and experiments including the Bigelow Expandable Activity Module (BEAM), Dragon will remain attached to Harmony for a month. For the first time, Dragon is occupying a port next door to the U.S. Orbital ATK Cygnus commercial cargo vehicle, which was berthed to the Unity module on March 26. (NASA) click on pic to enlarge
Here is an annotated picture of the current ISS – with all parking slots full. NASA put the development of ISS supply vehicles out to commercial contractors some years ago, and now they’re up and running. Read more at www.NASA.gov
Happy stargazing
Martin _________________________________________________________________________
April 10th 2016: Kepler 2 JD 245 7488.5
We have a splendid diagram from NASA showing the change of view for the new Kepler Mission. The Kepler probe suffered from a loss of two reaction wheels (stabilisers) and was all but written off.
However, the Kepler team has managed to give the probe a new life, by establishing stability basically using the pressure of sunlight… (the mind boggles) The probe is now 
referred to as Kepler 2 and has a new target area, looking for microlensing of stars towards centre of the galaxy.
This is the probe which collected the “shock breakout” pulse, (see Supernova below) click to enlarge
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March 15th 2016: More data from Cassini (in orbit around Saturn) and a statement from Carolyn Porco (director of imaging team) of new findings of satellite ENCELADUS
Click on pic to enlarge
“Today, the members of my imaging science team, using our high resolution images of Enceladus’ surface taken over the last 7 years, have confirmed that Enceladus’ water layer is indeed global. How did they do it? By looking for a libration … a small, cyclical, back-and-forth deviation from uniform rotation … and finding that it is present and much too large to be a libration of the entire body. The conclusion: It is a libration in the thin, outer ice shell only, indicating that ice shell and rocky core are decoupled and separated by a liquid layer. Sacre bleu! It has been a hard problem to solve, requiring persistence, painstaking analysis, an understanding of orbital and rotational dynamics, and bringing to bear the full and tedious brunt of statistical analysis. But it has yielded gold.”
Carolyn Porco, Director CYCLOPS, Boulder, CO
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February 11th 2016: The day that the detection of Gravitational Waves was announced.
LIGO Laser Interferometry Gravitational wave Observatory.
Gravitational Waves have been detected: 100 years after Einstein’s field equations which postulated their existence were published (in 1915.)
I think this artistic representation of two black-holes coalescing and producing the “chirp” that shook the world will remain an icon to be remembered. The mathematics involved in distinguishing movement of a mirror in the interferometer, a movement of an order of distance less that the size of the very molecules constituting that mirror, from the noise of its surroundings is astonishing. This is Fourier analysis beyond my ken. I believe Einstein said (1915) that Gravitational Waves would be difficult to detect. That’s true. The triangulation from the two detectors located the event to c 1.3 billion light years. How many more events can we expect, I believe / read / saw that there could be several per year with the present detectors.
Martin
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and now, for something completely different: The analemma
Not a dilemma, but a series of weekly photo shots of the Sun taken over a year at the same diurnal time (UT) from a fixed camera. The sequence above is attributed to a Russian astronomer. Note there are some missing (not 52) due to obscuring cloud. This shows the effect of Earth’s axial tilt and elliptical motion on the Sun’s position in the sky.
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If all the water in all the seas and lakes of earth was represented as a sphere it would be about eight hundred miles in diam.