Wednesday 22 April 2015

Venus, the Moon and Aldebaran the bulls eye


Looking west over the garden fence. The crescent Moon with earthshine illuminating the remainder of the earth facing surface and sitting just above the orange supergiant star Aldeberan (alpha tauri). Venus shining brightly above my neighbour's television aerial.
When I went to put some dishes in the dishwasher I noticed the crescent moon through a west facing window.  I quickly located the wherabouts of my DSLR and managed to capture not only the moon but also Venus and the star Aldebaran. I braced the telephoto lens of my camera on the top of my neighbour's fence and handheld an exposure of 1/15th of a second. No mean effort for a shakey old man!

Thursday 16 April 2015

Ganymede - largest moon in the solar system


Jupiter at 21.00 UTC on the 14th April 2015 - taken with my 127mm Meade Refractor and Canon 600D DSLR camera.
Jupiter's largest Galilean moon, Ganymede can be seen in the above image as a small black dot, transiting Jupiter's disc.  Io, the innermost and volcanically active Galilean moon,  can be seen just to Jupiter's lower left.  Europa can be seen further out.   I could see Callisto further out still but this moon was outside the field of view captured by my camera.

Completing an orbit in roughly seven days, Ganymede participates in a 1:2:4 orbital resonance with the moons Europa and Io, respectively. It has a diameter of 5,268 km (3,273 mi), 8% larger than that of the planet Mercury, but has only 45% of the latter's mass. Its diameter is 2% larger than that of Saturn's Titan, the second largest moon in the solar system. It also has the highest mass of all planetary satellites, with 2.02 times the mass of our Moon.

  
Ganymede has a magnetosphere, which implies the presence of a liquid iron core. The moon is comprised of silicate rocks and water ice and has a surface pocked with impact craters,. It is also considered likely that Ganymede hosts a subterranean salt water sea which along with Europa's subsurface ocean may harbour primitive extra terrestrial life.

Ganymede - Credit NASA Galileo Orbiter


Credits: Wikipedia and NASA