Messier 15 - globular star cluster in the constellation Pegasus

The Globular star cluster Messier 15 taken from our backyard using my 127mm refracting telescope and a Canon 600D DSLR at approx f=900mm

The globular star cluster M15 was discovered in 1746 by Jean-Dominique Maraldi. You can view the cluster from a dark site using standard 10x50mm binoculars. In binoculars it appears as a small fuzzy disc of light against the dark night sky close to the star Enif in the constellation Pegasus.

Location Map for M15.  North is up and South down, East is left and West right. The yellow square denotes the location of Messier 15

The cluster is approximately 33,600 light years distant from Earth, has a diameter of 175 light years and contains over one hundred thousand stars. If our planet circled a star in such a cluster, the night sky would be awash with starlight and night as we know it would not exist. Globular star clusters are located in galactic halos (ie. they are gravitationally bound to galaxies and buzz around them like bees to the hive.) The Milky Way galaxy in which we abide has over 150 globular star clusters in its halo.

Messier 15 is one of the most densely packed globulars known in the Milky Way galaxy. Its core has undergone a contraction known as 'core collapse' and it has a central density cusp with an enormous number of stars surrounding what may be a central black hole. 
 
The cluster is notable for containing a large number of variable stars (112) and pulsars (8), including one double neutron star system, M15 C.  M15 also contains Pease 1, the first planetary nebula discovered within a globular cluster in 1928. Just three others have been found in globular clusters since then.

An enlargement of my image to show the dense core of M15

Just think there could be a black hole lurking at the centre of this dense ball of stars. How good is that?

Credits: Wikipedia and StarMap Pro 9.

The Ice Giants

Uranus and two of its moons, Oberon and Titania as imaged from our backyard using a Canon 600D DSLR attached to my Meade 127mmm refracting telescope.

 Uranus will reach opposition (its nearest point to earth in the year) on the 7th October. Neptune is just past  opposition. As the early hours of the 25th of September were clear and transparent, I turned my telescope and camera towards the ice giant planets, Uranus and Neptune. Both shine by reflected sunlight and both are a very long way away.
 

The planet Uranus in a wide-field starry background

An infrared composite image of the two hemispheres of Uranus obtained with Keck Telescope adaptive optics. The component colors of blue, green, and red were obtained from images made at near infrared wavelengths of 1.26, 1.62, and 2.1 microns respectively. The images were obtained on July 11 and 12, 2004. The North pole is at 4 o'clock. Credit for image:
Lawrence Sromovsky, University of Wisconsin-Madison/ W.W. Keck Observatory

 Uranus is named after the progenitor of the Titans and father of Saturn. Uranus is an unusual planet in that it has a retrograde orbit around the Sun, it barrels along with its equatorial plane inclined at 98 degrees to its orbital plane. It is a world in deep freeze and has a blackbody temperature of only 59 degrees Kelvin above absolute zero.  Like Saturn, Uranus has rings but much much fainter and so they remained undiscovered until the Voyager spacecraft passed by in January 1986.  Uranus has 27 known moons, the largest Oberon and Titania were discovered by William Herschel in 1787.

For more facts about Uranus follow the link
http://nssdc.gsfc.nasa.gov/planetary/factsheet/uranusfact.html 

Neptune and its largest moon Triton (possibly) as imaged from our backyard using a Canon 600D DSLR attached to my Meade 127mmm refracting telescope.

Neptune is the last of the Jovian planets and the eighth planet from the sun. Unlike Uranus it has an internal heat source but as the heat it absorbs from sunlight is so reduced by its extreme distance from the sun, its temperature is only about 59 degrees Kelvin. The  Voyager spacecraft and the Hubble Space Telescope have both imaged a Great Dark Spot in Neptune's clouds.

The planet Neptune in a wide-field starry background

Neptune as imaged by the Voyager space craft in 1989 from a distance of 5000km

Neptune has fourteen known moons. Triton, the largest moon has a retrograde motion.  Neptune and Uranus are both gas giants with similar densities and masses. Their cold atmospheres contain water ice and ammonia ice mixed with gaseous methane, hydrogen and helium.

For more facts about Neptune follow the link:
http://nssdc.gsfc.nasa.gov/planetary/factsheet/neptunefact.html

Credits: Wikipedia and NASA

Transient Lunar Phenomena

A transient event in the Crater Anaxagoras near the Lunar Limb captured last night from our backyard at 10.00pm BST

Last night was not clear enough for gainful astro-imaging, so instead I busied myself with calibrating the focusing of my planetary camera at a number of F values. The moon presented about half phase and was an ideal object to focus upon. Sadly, the gum trees at the bottom of our garden and some hazy high level cloud prevented me from capturing any really sharp images.

As I watched the moon sailing serenely across the sky my mind turned to the observation of 'Transient Lunar Phenomena (TLPs)'

"A transient lunar phenomenon (TLP), or lunar transient phenomenon (LTP), is a short-lived light, color, or change in appearance on the surface of the moon.
Claims of short-lived lunar phenomena go back at least 1,000 years, with some having been observed independently by multiple witnesses or reputable scientists. Nevertheless, the majority of transient lunar phenomenon reports are irreproducible and do not possess adequate control experiments that could be used to distinguish among alternative hypotheses to explain their origins. Thus, few reports concerning these phenomena are ever published in peer reviewed scientific journals, and the lunar scientific community rarely discusses these observations.
Most lunar scientists will acknowledge that transient events such as out-gassing and impact cratering do occur over geologic time: the controversy lies in the frequency of such events.
The term was created by Patrick Moore during his co-authoring of NASA Technical Report R-277 Chronological Catalog of Reported Lunar Events, published in 1968." Credit Wikipedia

For more information on Transient Lunar Phenomena follow the link
http://en.wikipedia.org/wiki/Transient_lunar_phenomenon