Posts Tagged ‘Moon’

King Harvest

Caught between the rooftops and an advancing blanket of cloud, Sunday’s Harvest Moon managed to reveal itself for a few brief moments as it rose into the sky. Taking place around the time of the autumnal equinox, the Harvest Moon is unique because it rises 30 rather than 50 minutes later each successive evening.

This happens because the path of the Moon on the ecliptic forms a narrow angle with respect to the horizon. An occurrence which results in shorter rising times with no period of darkness between Sunsets and Moonrises. In times long past this helped farmers, as they could work for much longer, when it became time to gather in their crops. Hence the name of this full Moon.

Harvest Moon Rising 04.10.09: Mouseover the image for a close-up.

The offhand shot above, a 1/40 second exposure, was taken at a focal length of 70mm using an f/stop of 5.6 and an ISO of 100. The image was then processed using a combination of Apple’s Aperture and the open source image editor GIMP.

Three Times the Charm

Jupiter µ Capricorni Neptune 110709

Jupiter, the majestic giant of the solar system, has always been my favourite planet. While Saturn delivers undeniably glorious views; Jupiter, at least for me, has always stolen the show. Having suffered a grueling month of cloudy evenings, and twilight nights, the chance to take in an observation of this dazzling planetary behemoth early on Saturday morning was a welcome one.

The fact that Jupiter was in conjunction with Neptune, and the star µ (Mu) Capricorni just added to the celestial spectacle. My view however was to be a short lived one. Due to the urban geography of the neighbourhood; both planets remained in my sights for only 16 minutes before disappearing behind the row of three storey buildings that line the front of the house.

A Planetary Dance

Despite my brief window of opportunity I was afforded a stunning observation. The 25mm Celestron plössl revealed the equatorial belts of Jupiter as rust coloured bands, while the four moons: Callisto, Ganymede, Io, and Europa beamed like a string of brilliant diamonds against the dark sky. Having conducted my most recent observations of Jupiter with the 25×100 Strathspey binoculars; it was a real pleasure to see this distant world with such clarity.

While Jupiter made a striking impression; Neptune, bathing in the alabaster light of the waning gibbous Moon, was just discernible as a faint point of light with a hazy turquoise hue. This is the second time that I have been fortunate enough to view this remote ice giant which sits just over 2 billion miles from the Earth. Gazing upon this diminutive speck you realise that you are actually looking at the end of planetary space beyond which begins the Kupier belt, the Oort cloud, and finally galactic space. An amazing, but rather humbling thought.

In between this planetary dance µ Capricorni, a yellow-white F3 IV type subgiant that lies 90.2 light years away, cast it’s white incandescent light upon the scene. Subgiants are stars which have, or are in the process of ending hydrogen fusion. Beyond this point in it’s evolution µ Capricorni is destined to become a red giant that may, at some point in the far flung future, bloom into a planetary nebula.

As quickly as Jupiter, and Neptune had risen above the roof tops then no sooner were they gone. Hidden from view by the suburban sprawl. Left alone with the Moon, which made for a very tempting target, I decided to make the most of it by taking in one more special observation before packing up.

One Giant Leap

Forty years ago, on the 20th of July 1969, NASA realised the mandate that the late President John F. Kennedy had laid down eight years earlier: to land a man on the Moon, and return him safely to the Earth. Apollo 11, carrying the astronauts Neil Armstrong, Michael Collins, and Edwin ‘Buzz’ Aldrin, set down near the south western shore of the Mare Tranquillitatis, and made history.

It was here that I aimed the telescope in search of three small craterlets: Aldrin, Collins, and Armstrong; all of which form a chain just east of the larger impact craters Ritter, and Sabine. After ten minutes of continued scrutiny the 6mm plössl finally resolved these three small monuments to the first manned lunar landing. In reality Aldrin, Collins, and Armstrong range in size from 2.4 Km to 4.6 Km giving some idea of just how vast this region of the Moon really is.

Letting my gaze drift down not far from Collins I imagined the quiescent remnants of Tranquility Base, also known as Statio Tranquillitatis, forever frozen in time by the vacuum of space. A lasting testament not only to the triumph of Apollo 11, or the United States of America, but probably the single greatest achievement Mankind has ever made. Where the 21st Century will take space exploration is anyone’s guess, but hopefully one day humanity will find itself once again voyaging to the Moon, and beyond.

If you have the time then why not follow in the footsteps of the Apollo 11 astronauts by tracking down the craterlets Aldrin, Collins, and Armstrong yourself. The best time to do this is nearer the end of the month, on the 27th of July, five days after the new Moon. I’d also recommend that you  take in an view of Jupiter, and Neptune as they drift past one another in the night sky. This is the second of three conjunctions that will take place between these two planets during the year, with the third one to occur on the 20th of December. Have fun, and happy observing!

Moon Safari

The Moon is, and always has been a favourite observing target of mine. So when last weekend (30.05.09) brought some beautiful clear skies with it; I took the opportunity to explore some new lunar locations as well as revisit some old ones. There was so much to see that I couldn’t possibly fit it all into this blog post. However two features that really stood out for me were: Rima Ariadaeus and Rima Hyginus; both impressive rilles that lie near the west coast of the Mare Tranquillitatis.

The word rille is used to describe the various depressions, or trenches that can be seen scarring the surface of the Moon. The term was used by early observers to characterize such lunar objects and was probably introduced by the German astronomer Johann Schröter in about 1800. More recently the latin word rima (meaning fissure) is often used interchangeably with the word rille to describe the same kind of feature.

Rilles can be divided into three categories: linear, arcuate and sinuous. Those of the first type are thought to be grabens: extended slabs of crust that have collapsed between parallel faults. They are comparatively straight, flat-floored and are sometimes associated with crater chains. In comparison arcuate rilles have smooth curves and are often observed near the edges of the lunar maria. They are believed to have formed when the lava that established the maria cooled, contracted and sank. The sinuous variety seem to be similar to the channels that lava flows on Earth produce, but these lunar valleys are far more rambling; perhaps because the ancient lavas that spread across the Moon were more fluid than those found on Earth.

Moon Safari

The shadowy laceration of Rima Ariadaeus, a 300 Km long graben, offered a wonderful view through the five inch refractor. At around 3.85 to 3.2 billion years old this lunar fault formed some time between the late, or early Imbrian epochs. A violent period characterized by colossal impacts and vast volcanic eruptions that formed the lunar maria that we see today.

Conversely Rima Hyginus proved just a little harder to find, but only because I had chosen to look for it when low light conditions were not at there optimum. This hybrid rille, also an Imbrian formation, evolved through a fault that was subsequently altered by volcanic activity. Closer inspection of this lunar feature reveals that it ramifies by adjoining Rima Ariadaeus via a shallow groove towards the north east.

Both of these rilles made for wonderful viewing and testify to the Moon’s tumultous past. So if you haven’t done so already I would thoroughly recommend that you take in an observation of these two fascinating lunar objects. A minimum aperture of around 90mm is almost certainly needed, and I would advise searching for them both around six days after a new Moon, or five days after a full Moon. Just be careful that you don’t get stuck in a groove!

Three is a Magic Number

Skirting the western shore of the Mare Nectaris you will find three fascinating craters: Theophilus, Cyrillus and Catharina — all of which beautifully illustrate the evolution of lunar geomorphology caused by impact erosion. Turning the Celestron Omni 120 here last week (30.04.09) really was a treat and left me in no doubt about what I’ve been missing out on since I returned to amateur astronomy. The view just blew me away and I spent the next hour picking my way across the wreckage of this ancient landscape. See here for details: www.lpod.org

Theophilus was the first of my targets and the youngest of the crater trio which formed some time around the Eratostherian period. While the four jagged peaks of the impressive central mountain were clearly defined it was the intricate detail in and around the robust terraced walls that caught my eye. The contorted ridges that I could see radiated away from the smooth crater floor like ripples in a pool of water and made for an exceptional observation.

Lying to the south west, and slightly overlapped by Theophilus in the north east, the soft but tortured outline of Cyrillus marked itself out against the surface. This lunar relic dates from the earlier Nectarian period when the Moon was battered by massive impacts that created the major lunar basins. Looking within Cyrillus itself the three imposing mountains that rise around one kilometer from the floor of the crater stood out prominently, while the shadow filled Cyrillus A clung to the deteriorating south west verge. At this point I took a moment to examine Cyrillus’ wall’s and noted the state of deterioration, but it was nothing compared to Catharina’s decimated appearance.

An irregular and ruinous formation; Catharina presented itself in all it’s ramshackle glory not far from Cyrillus. This crater was also formed around the Nectarian period, but it was clear to see that it had suffered extensive damage from further impacts. The shadowy veil of Catharina P made a bold impression where it had obliterated the northern wall, while little remained of the crater embankment to the north east where Catharina B, and G had impacted. Casting my gaze towards the southern interior I easily spotted the dark silhouette of Catharina S watching over the remains of the crumbling rampart, while the shadowy outline of Catharina C embedded itself into the outer exterior of the crater.

There is so much detail to be had from this region of the Moon that it will keep you coming back again and again. If you want to study a good example of crater degradation then this trio will not disappoint.  All are visible with 10×50 binoculars and personally speaking I have had some pretty good views through my 25×100 binoculars. However for seriously good observations a telescope in the region of 90mm and above will be needed.

To see Theophilus, Cyrillus and Catharina at their best I would recommend observing them when the Moon is either four to six days old, or when it is nineteen to twenty days old. So make sure you mark those times in your diary, and be sure to get out and take a good look at this display of “beautiful devastation”.

MoonWatch: Day 9

Sunday (05.04.09) marked the end of MoonWatch week, which for me has been a fun event to celebrate even if the weather has not always cooperated. On this occasion the promising blue evening sky had given way to the fog like veil of cirrostratus cloud later that night, which I would have cursed at any other time if it weren’t for the hazy lunar corona that it was helping to create.

waxing-gibbous-moon-050409

With Regulus in Leo sitting just above the Moon I decided to use the Bresser 10×50s mounted on the tripod to make a wide field observation. Trying to identify the number of lunar objects that I could see at this magnification was also quite fun. Near the southern terminator I could partially discern the Mare Nubium while to the north I could easily make out the giant ray crater Copernicus and the Mare Imbrium. The vast bay of the Sinus Iridium and the dark, lava filled crater Plato were also clearly visible in and around this area.

Looking eastwards I had no problem observing the dark stains of the brightly lit Maria — this included the Mare: Serenitatis, Vaporum, Tranquillitatis, Crisium & Foecunditatis — while the bright rays of Langrenus and the outlines of Petavius as well as Furnerius were all visible. I also managed to catch (with some added scrutiny) the smaller ray craters Manilius, Menelaus and Proclus, all of which looked like minute pin-pricks of light against the lunar surface.

By the time I had finished making a preliminary sketch the cloud cover had grown just that little bit thicker. It looked more and more likely that a blanket of stratus would begin to roll  in from the west quite soon so I was happy to have made the observation when I did. All in all I have to say that this short lunar jaunt was the perfect way to end the first MoonWatch week. The second MoonWatch week won’t take place until late October, just after Jupiter SkyWatch week — both of which I’m really looking forward to. In between then and now I’m hoping to complete the Binocular Messier Club list and make some headway with the Lunar 100, which is more than enough to keep this amateur astronomer busy for some time.

[Post edited: 07.04.09]