Archive for the ‘Gibbous Moon’ Category

3 May 2012

Since we wrote the last blog, we have joined a Star Hoppers group led by our US mentor Greg. Most of the members are on the east coast of the US. We are the only two, as far as I know, Down Under. The aim of the group is to apply the classic advice of Sherlock Holmes – learn to “observe,” not simply to “see.”

And what should we observe in the first two weeks of May?

 “Good targets for viewing under dark skies are the Beehive (with binoculars or a low power scope), several double stars in Cancer and Leo or the galaxies in Leo.”  

We have to pick 3 – 5 targets on any given night.

The targets for May are fortunately also in constellations in our southern sky.

Constellations of Cancer and Leo

Stellarium image of constellations of Cancer and Leo (click on image to enlarge)

Waiting, waiting

Primed and ready – we waited for the weather to give us a break.

When weather reports of the last few months promised clear skies, they often didn’t mention the evening clouds that creep in, uninvited, and destroy any chance of viewing the stars.  So we’ve invented a new game to amuse ourselves: it’s called “Wither goes the weather?”

On the evening of the 3rd May, around 8 pm, we were pleasantly surprised to find the sky was clear of pesky clouds. When we walked out on to car deck observatory the panorama was breath-taking even with lights on everywhere and moonlight bathing the street. And the air was cool and calm. Perfect for viewing!

Dish of the sky

Stellarium image: Dish of the sky (click on image to enlarge)

Sure our view wasn’t quite as detailed as this, but with all those fairly large objects in view, we were very excited.

Starting from north – Mars was pretending to be one of the stars of Leo, forming a neat triangle with Regulus and Algieba.

Moving past the fat Gibbous Moon, and going east was Saturn, a golden brooch on the skirt of Virgo.

Looking south over Francis Street were the Pointers doing their job of showing us the Southern Cross.

Southern Cross and Pointers

A slide along the Milky Way and we were looking west at Canis Major (Big Dog) lying on his back wearing Sirius like a trophy on his chest. And caught in the moonlight (or should I say despite the moonlight) a hare, Lepus, being chased by the Big Dog. What a beautiful constellation this is! A neat curve of stars.

Just below the Big Dog is his master Orion slipping down sideways behind the trees!

View of western sky

Our photo: View of western sky (Click on image to enlarge

Spoilt for choice

How to choose three targets? Spoilt for choice, weren’t we? So we did what one does at a smorgasbord crammed with too many delectable dishes. We decided for our first night of star hopping to sample every big star and planet we could see and look for doubles and galaxies and clusters before we committed ourselves to three.

 Using our binoculars we star-and-planet hopped. With the Moon between Leo and Virgo, we were lucky to see Regulus and Algieba, but swinging to the Cross we saw the Jewel Box displaying its contents near Beta Crucis. And in the vicinity was the king of globular clusters – Omega Centaurus.

Going down the Milky Way, watered down by the light of the Moon and the lights on in every home in Francis street (people don’t believe in curtains or blinds), we looked for M41 in Canis Major, and found it rather faint. Caught M42 in Orion’s sword just before the Hunter slipped off on his perpetual chase of the Scorpion.

With the sky still clear at 8.30 pm we decided it was time to bring out the scope and look at the planets. Mars was a nice round reddish disk, but Saturn, despite the light of the Moon, beat the god of war in the beauty stakes. Saturn is certainly the pin-up boy of the planets! We could just see its moon, Titan; the other moons were drowned out by the light of the Moon.

Had we been able to see them, this is what we would have seen.

Saturn with moons

We’ll keep that treat for another night.

Turning our sights to the Moon

Having had our fill of stars and planets we turned the scope with the 6mm eyepiece on the Moon. OMG! The angle of the light from the sun lit up craters and mares perfectly, casting shadows to show them in 3D. We have never seen crater Aristarchus with Vallis Schroteri and  crater Herodotus  in such good light. It was the feature of the night.

Some features of the Moon

Another striking feature in this light was the Bay of Rainbows with crater Bianchini clearly visible as were the other four or five craters in the neighbourhood. And then looking toward the edge of the Moon was a rather angular crater with a prominent peak. I think it is Babbage, or perhaps Pythagoras.

We could even see the Rectii range, an unusually straight range in the Sea of Showers.

Blindingly brilliant were Copernicus, Kepler and up at the top Tycho. But another crater that stood out very clearly, so that we could even discern where its rim is broken, was Gassendi on Mare Humorum. With Gassendi A, this crater looks like an engagement ring with a big diamond.

After a month’s starvation of night sky viewing, we feasted on this evening’s gifts of a clear and still night.  An hour and a half of uninterrupted viewing was more than we hoped for, so when the clouds came over at 9.30 pm, we folded our scope without a word of complaint.

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12 Mar 2012

Lately we have been getting an occasional glimpse of bright planets between clouds.

This evening a friend from Melbourne, who is also enthused about celestial happenings, excitedly rang to read us an item on the movements of Jupiter and Venus in the western sky. Thanks to that reminder we went out into Street Observatory at 8 o’clock. Our street runs east to west.

We had to walk up the street a little and stand near the middle of a traffic lane to get the best view.  Fortunately traffic was light, and Dom had a red torch to warn oncoming cars.  We looked west and beheld Venus and Jupiter – beautiful and bright.

As Greg, my mentor said, “Despite all my fascination with telescopes, I still get a thrill out of simply seeing the planets in the night sky and watching them change positions. It helps – for me, anyways – to understand what’s going on ‘backstage’. But people need to rediscover what you have found – simply look up at night – it’s a great show, we spend too much time in our caves!”

Venus and Jupiter on 12th March 2012

Venus and Jupiter on 12th March 2012 (Click on image to enlarge)

Having had our fill of Jupiter and Venus in the backdrop to our street, we folded the tripod and turned towards home. The celestial backdrop continued to the north.  We recognized Mars above the roof line of houses. Placing the tripod on a neighbour’s driveway I was focusing on Mars when a car stopped and the driver leaned out and said, “What are you photographing?” just in case we were spying into someone’s window.

“Mars”, Dom told the astonished man, “Right over the roof there!”

“So it is,” he said. “And it is red! Wow!”

Mars on 12th March 2012

Mars on 12th March 2012 (Click on image to enlarge)

We turned again and looked the other way downFrancis Street and lo and behold! The Cross and Pointers were looking down on us!

Southern Cross and Pointers

Southern Cross and Pointers (Click on image to enlarge)

I thought, hopefully, “Maybe at last, good sky watching times are here!”

After processing the photographs, I went to Bedroom Observatory at about 11 pm. Another planet, this time Saturn with the star Spica in Virgo were shining due east. Looking further east was the bright glow of the Gibbous Moon. I grabbed the binoculars and noticed that the angle of light had the section between Tycho and Mare Nectaris clearly outlining the craters.  I had not seen the SE sector so clearly. Craters everywhere. Several caught my eye and I tried to memorize their positions. Though the angle was awkward for the camera, I had to get a shot.

Gibbous Moon

Gibbous Moon (click on image to enlarge)

Dom and I pondered over the map a long while to identify Theophilus with the imposing central mountain. Tucked into the side of  Theophilus,  is Cyrillus.  The third in this neat threesome on the banks of Mare Nectaris is Catharina. The map is beautiful, but oh! how much more gorgeous is the real thing especially when the craters are in 3D.

Oh! what a night!

I need to spend more time studying some of the other craters that were clearly in the light.

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4 February 2012

When the weather forecast for the next three weeks promised only two clear nights, I knew those two were going to be very long nights glued to the binoculars. My patience was rewarded.  The Gibbous Moon shone splendidly outside Bedroom Observatory, and we photographed it easily. 

Gibbous Moon

Gibbous Moon (click on image to enlarge)

The first thing I notice is there’s a smorgasbord of features. So, like a diet conscious eater, I am going to pick out just the most delectable. The maria, centre and left, are beautifully displayed, so I decide to start with them. Up the top is the small Sea of Nectar. In shape it looks like a big dark D with a cherry on top. The straight edge of the D is to our east where it abuts the terrae that separates it from the Sea of Fertility. In that terrae, several mountain peaks of the Pyrennes mountains sparkle in the light.

 The “cherry” on the top of the D of the Sea of Nectar, I discover, the Crater Fracastorius which is a flooded crater whose rim is disintegrating. More interesting is the bright spot to the north of Fracastorius which is Crater Rosse. With its high albedo, Rosse a mere 12 km across, stands out against the dark volcanic lava of the mare. A feature of the Moon does not have to be large to catch the eye! Rosse does not have its own rays, but notice the ray that comes all the way from Tycho, brushes past the western wall of Fracastorius and then points to Rosse – that’s quite a long ray – at least 1800 km!

 Crater Rosse was named after the Irish Astronomer William Parsons, the 3rd Earl of Rosse. His claim to fame: building the largest telescope in 1847 and cataloguing many galaxies.

Gibbous Moon with Sea of Nectar

Gibbous Moon with Sea of Nectar (click on image to enlarge)

On the other side of the Pyrenees range is the large Sea of Fertility. Tucked into its eastern side is a large white circle which is the Crater Langrenus. The Flemish Astronomer Michel Florent van Langren who was the first to draw a lunar map named this crater after himself. When Riccioli and the others renamed all the lunar features, they left Crater Langrenus be!

The features of Langrenus are not too clear in this light but I will look at it during other phases. Astronaut James Lovell described it during the Apollo 8 mission as “quite a huge crater; it’s got a central cone to it. The walls of the crater are terraced, about six or seven terraces on the way down.”

Gibbous Moon with Sea of Fertility

Gibbous Moon with Sea of Fertility (click on image to enlarge)

To the west of the Sea of Fertility across a large terrae with several bright peaks is the Sea of Tranquility. The top (south) part of this sea looks like a clenched fist with an outstretched thumb on which balances the Sea of Nectar. There are many interesting features of the Sea of Tranquilityto investigate, but the one that catches my eye is the light grey patch which nestles along the north-eastern edge facing the Sea of Crisis.

Called Pauli Somni, (Marsh of Sleep), it has a higher albedo than the lunar mare and has a diameter of 143 km. In 1907 the marsh was described as having “a color which is unique upon the moon, a kind of light brown, quite unlike the hue of any of the other plains or mountain regions”. Not sure about the light brown as I just saw it as grey through the binoculars.

Hugging the top edge of the marsh is the curve of Sinus Concordiae (Bayof Harmony) and at the bottom edge, Sinus Amoris (Bayof Love). Sleep between Harmony and Love — sounds like a good recipe for Tranquility!

Gibbous Moon with Sea of Tranquility

Gibbous Moon with Sea of Tranquility (click on image to enlarge)

The Sea of Serenity is the last mare I am looking at tonight. Both Luna 21 and Apollo 17 landed near the east border of this sea, in the area of the Montes Taurus range.

As I look at the Sea of Serenity, I pick our two craters Menelaus and Posidonius.

Posidonius was a multi-talented Greek: a philosopher, politician, astronomer, geographer, historian and teacher. In astronomy, among other things, he worked on the size and distance of the sun and moon from Earth. All this in 90 BCE, and all without any of the sophisticated equipment we now have!

An interesting note:

“The Luna Society voted unanimously to designate a Lunar crater for Michael Jackson (formerly Posidonius J) in honor of the legendary entertainer and prominent Moon property owner.” Michael Jackson would have been pleased – he did perfect the moon walk!

With my binoculars I can’t see this tiny crater on the rim of Posidonius, but what caught my interest in this little item was that one can buy real estate on the Moon!

Crater Menelaus is on the southern shore of the Sea of Serenity. You can’t miss it with its high albedo and it’s amazing to see a ray from the crater clearly crossing the mare. The crater is named after Menelaus of Alexandria, mathematician and astronomer. Some suggest it could be the Menelaus in the Iliad, whom Helen ditched to take off with the handsomeParis, causing the Trojan War! Somehow I don’t think it is that Menelaus!

“I hope you are going to show where Apollo 17 landed! After all it was the last manned lunar landing!” Dom suggested

“Oh okay! I’ll put a little star at the approximate spot!” Little boys!

Gibbous Moon witih Sea of Serenity

Gibbous Moon witih Sea of Serenity (click image to enlarge)

Having identified 10 new features, I call it a night. More to-morrow – the second clear night promised!

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11 Jan 2012 

Today at sunset black clouds covered the overhead sky and the vital eastern horizon.  “Patience,” I advised myself, for there was still time before moonrise; time enough to watch some mindless TV repeats.  Ho-hum.    

I looked out the window around 9.30 to see if the clouds had shifted – nah! It was about the time the Moon was rising. Oh well, I was resigned to not being able to see it to-night. 

At 10.45 pm, on my way to bed I glanced out and gasped in surprise… clear skies! The Moon was shining through our neighbour’s palm tree. Big and bright.

Moon rising through palm tree

Moon rising through palm tree (Click on image to enlarge)

We watched it rise and then looked at it through the binocs and instantly recognized the prominent craters: Tycho (the belly button of the rockmelon or cantaloupe); Copernicus (the large one); Kepler (the prominent one) and Aristarchus (the bright spot).

Four craters on 11 January 2012

Four craters on 11 January 2012 (Click on image to enlarge)

Even to the naked eye, the surface of the Moon is uneven – it has patches of bright and rough areas as well as dark and smooth areas. The rough areas are called terrae, the Latin word for land; and the dark areas are called maria pronounced mahr-ee-uh. It is the Latin word for ‘seas’; the singular is mare pronounced mahr-ey. Early astronomers mistakenly thought these dark areas were bodies of water. We know now that the lunar maria consist of volcanic basalts. Massive impacts with meteoroids created basins which later filled with lava and cooled.

 Being rich in iron the ‘seas’ are not as reflective as the higher terrae and so appear dark. The maria cover about 16 percent of the total lunar surface, most of them being on the side we can see from Earth. They are much older than the craters — some billions of years old — and much, much wider.

 We noticed that as the Moon was beginning its waning cycle: the left side was sliding into darkness. On the top left, on the edge of darkness, we could see very clearly a big dark spot with a distinctive ridge. This is the mare named the Sea of Crisis; it is 418 km wide.

Sea of Crisis

Sea of Crisis (Click on image to enlarge)

To the right of the Sea of Crisis are a series of three maria.

  • the Sea of Fertility is 909 km wide – about the distance from Sydney to Melbourne,
  • the Sea of Tranquility 873 km, and
  • the Sea of Serenity 707 km.

    Four Seas of the Moon

    Four Seas of the Moon (Click on image to enlarge)

The small dark mare to the right of the Sea of Fertility is the 333 km wide Sea of Nectar– a little more than the distance between Sydney and Canberra.

In 1651 Riccioli systematically named the features of the Moon, but the naming of the seas does not have the romance of the naming of the craters. For the craters he used names of people: from ancient Greece and Rome and scholars, writers, and philosophers from medieval Europe and Arabic regions.

For the maria, Riccioli dipped into the lore of the Moon.  The Moon was supposed to affect human conditions as well as the weather.  Based on the imagined influence of the Moon, Riccioli came up with names like the Sea of Crisis, Sea of Serenity and Sea of Fertility. Also Sea of Clouds, Sea of Storms and so on. Riccioli named them in Latin; I’ve used the English translations.

Nine Seas and four Craters of the Moon

Nine Seas and four Craters of the Moon (Click image to enlarge)

Swinging to the right, in the big less defined dark patches of the Moon, the maria from the top are:

The Sea of Clouds, closest to Tycho; then to its right, the Sea of Moisture, 389 km wide. The Ocean of Storms is the very large patch, 2568 km wide, around Kepler and Aristarchus. And to the left and below Copernicus is the Sea of Showers, 1123 km wide.

I have noted the widths of these maria, more to be impressed than to remember them.

Now a quick peek at what we saw on the 12th Jan 2011. The Moon is becoming more egg-shaped and the area of the Moon that is close to the edge of darkness is becoming very sharply defined. To the left of Tycho the ruggedness of the terrae is becoming apparent.  Further down, to the left of the Sea of Serenity, two perfectly scooped craters are clearly visible.   We playfully call them “snake-eyes”!

Moon on 12th Jan 2012

Moon on 12th Jan 2012 (Click on image to enlarge)

This phase, known as the Gibbous Moon, is when the illuminated portion is greater than half but less than a full Moon. Gibbous means hunch-backed.

The phases of the Moon have to do with the position of the Moon and Sun in relation to Earth. At Full Moon on the 9th, the Sun and Moon were on opposite sides of the Earth at 180-degrees. After that the angle has begun to narrow, and the Moon has become Gibbous. Next it will be Half, then a Crescent, then “No Moon” before it starts to wax and go through the cycle to Full Moon again.

A comparison of the Moon on the 11th and 12th January 2012 shows how the Moon is waning.

Moon on the 11th and 12th Jan 2012

Moon on the 11th and 12th Jan 2012 (Click on image to enlarge)

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