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Thursday, December 20, 2012

Solstice on Doomsday!

December 21st is a significant date for a few reasons.
Every year around this date the Earth reaches a position around the Sun that causes the south pole to lean/tilt towards the Sun at its greatest extent. This is known as Solstice, which means "Sun-stationary".
This could mean its an ideal time to buy lots of nice pens, pencils and rulers illustrated with smiley-face suns for Christmas or.... that the Sun, having gradually shifted more toward the South each day for the past few months, has now reached its Southern-most point in the sky. Therefore with each new sunrise after 21st December, the Sun appears to reverse course and shift back towards the Northern half of the sky.


The effects of the Solstice are the related to the seasons, as the intensity of sunlight varies at different places on the Earth.
Commonly known as Winter Solstice, it also results in the shortest daylight hours and longest night of year in northern hemisphere countries. At the same time, southern hemisphere countries experience their Summer Solstice or longest daylight hours/shortest nights.

Naturally there are lots of cultural events and festivals around this time. In Singapore, some of those of Chinese ancestry celebrate with family and friends by eating a dessert known as tangyuan 湯圓


The region that receives the most intense sunlight at this time of year is known as the Tropic of Capricorn. This is because the Sun's position in the sky during this time (i.e. its southernmost point), used to be directly in front of the constellation Capricornus.
However, the Earth's tend to wobble as it rotates and over thousands of years this wobble (known as precession) resulted in the Sun's southern solstice position shifting into the neighbouring constellation of Sagittarius. I guess someone should go re-label all those globes and maps and replace the Tropic of Capricorn with "Tropic of Sagittarius". At the same time they should also change the northernmost position of the Sun as well (i.e. Tropic of Cancer Gemini).



Solstice in Singapore
As mentioned in my previous post during the June Solstice, the effects on equatorial regions, such as Singapore, are much more subtle.

Slightly north of the equator, Singapore also experiences its shortest daylight hours, roughly 12hrs 3mins 2secs from sunset to sunrise, but this does not coincide with the latest sunrise, which occurs during February in the tropics.
Solstice marks the time when Singapore sunrise becomes later than 7am (i.e.7:01am). From now until February, sunrise will gradually get later and later, so you can enjoy a few extra minutes of darkness in the morning.

Sun's position 9am June - Facing east, Sun rises from North-East (left)

Sun's position 9am December - Facing east, Sun rises from South-East (right)
At June/Northern Solstice the Sun rises from the North-East direction and sets North-West.
In December, sunrise is from South East and sunset South-West. Therefore, those with south-facing windows can expect more sunlight at this time of year, while north-facing window enjoy more shade. However, in December its raining most of the time, so it probably won't make much of a difference.


End of the year world
Finally, 21st December 2012 is now more well known for its association with the ending of an ancient Mayan calendar.
Mayan Pyramid of the Moon
These ancient Central Americans kept track of the days in the following way:
1 day is called a k’in.
20 days is referred to as 1 winal.
360 days is called 1 tun.
A period of 20 tuns is called 1 k’atun
20 k’atuns are grouped into 1 b’ak’tun, which is equal to 144,000 days.


This so called Mesoamerican Long Count Calendar ends after a cycle of 13 b'ak'tuns, which when translated to our modern Gregorian Calendar finishes on 21st December 2012. 
Many scholars and scientists  think that after this date the calendar simply repeats itself or starts again, similar to how we always start back at January every year.
However, there are many other ideas out there that have developed over time, referring to doomsday and the end of the world. Many are based on scientific findings and events like asteroid collisions, planetary alignments and solar storms but have been extremely exaggerated and highly unlikely.
I think its all just a great excuse to make tonnes of movies, documentaries, write books and articles.
I guess we will find out soon!

Wednesday, December 19, 2012

December Updates - Part 2

It was a fascinating night last Friday, with one of the clearest skies we had at SCOB in several weeks. A large patch of cloud drifted by in the early evening but towards the end of the session, things cleared up again and, with no Moon around, many of the familiar December stars were free to shine as best they could in our light polluted sky.
Photo of the constellations Orion (top), Canis Major with Sirius (right), Canis Minor and Procyon (below in cloud) and parts of Gemini (lower left).
Initially, most of our attention was focused on Jupiter. During the most crowded period we were watching as Jupiter's moon Io gradually appeared out from the giant planet's shadow.
Didn't have a camera handy at that point but after closing time I took a few snaps of the Jupiter and the surrounding area of Taurus, including the Pleiades (M45) star cluster.
Long exposure photo of Taurus (v-shaped) with Jupiter (brightest object) and Pleiades Star Cluster (centre).

To finish the evening we had a last look at the great Orion Nebula (M42). I attached the camera to our main 16 inch telescope but didn't manage to reach the correct focal point, so switched to the 6 inch refractor for a "quick" 30 second exposure before the battery went flat. Next time, must remember to be more prepared and get all this photograph stuff ready early. I'm still new to astrophotography and with all the other things going on it tend to be last on my mind.
Orion Nebula M42 through 6 inch refractor telescope using a Nikon D70s camera.  The central collection of stars is known as the Trapezium, because of the four brightest stars but if you look closely there are actually 6 stars. 

The central collection of stars is known as the Trapezium, because of the four brightest stars but if you look closely there are actually 6 stars. Many visitors often confuse the three stars at the bottom with Orion's Belt. I guess its easy to form a connection between the two as the telescope is roughly pointing in the same direction as the belt, which makes it harder to grasp the concept that what we're looking at only occupies a tiny speck of sky and cannot be fully observed by the eye alone.

At one point that night we tried pointing our telescope at the Andromeda Galaxy M31, with an experienced eye I could make out the faint glow of its core but to many of our visitors it was almost invisible, I recall seeing a few blank expressions as I tried to explain about using averted vision :/

That's all for now!

Wednesday, December 12, 2012

December update

Its's 12-12-12, and I haven't done any update yet for December.
As expected the weather is still very cloudy and rainy. There were a few clear nights last week so once again I was out with my camera to take a few shots of this month's bright celestial highlights.
In particular Jupiter, Taurus and Orion. The Bull and Hunter always appear in the East during the early evening in December. This year, they are accompanied by the largest  (and second brightest) planet, Jupiter.


Over the next few weeks,  Jupiter will slower move away from Taurus's bright star Aldebaran (the follower). Later in the evening and toward the end of the month, Sirius, the brightest star in the sky will also appear, shining brightly south-east of Orion.

December is usually a good month for watching meteors/shooting star, with the Geminids meteor shower peaking around 13th-14th December (this week in fact!).
With an expected high rate of meteors and no Moon in the night sky, its bound to be the best shower of 2012.
However, in a bright city like Singapore, in the middle of the rainy season, the chances of seeing any shooting stars are significantly reduced, oh well. If we get a clear night sky of the next few days and you stare at the sky for a few hours after midnight it will increase your chances.


Other things happening this month include, Venus and Saturn still there in the early morning around 6am-7am towards the East. Mercury is there too but low altitude makes it very difficult to spot in the usual morning hazy.

21st December is southern solstice, which makes the southern most position of the Sun in the sky. Southern hemisphere countries will also experience their longest daylight hours, while the north has the shortest daylight hours. More on this in a future post.

Moon Dates for December:
We'll be observing the Moon at SCOB on Friday 21st Dec & Friday 28th Dec.


Finally, our school holiday activities are still available and going strong at SCOB every Friday evening this month.

During the past few weeks the planetarium has been the most popular activity, with light painting a close second. We also have a few items, such as astronomical 3D postcards, for sale. Surprisingly, the astronaut ice cream as been an unexpected hit.

Occasionally, we have a few visitors pop by, who appeared to have lost their way. For instance, this guy, who kept asking about some rebel base?????????


Thursday, November 29, 2012

School holiday activities

From now until the end of December we've added a few more activities to our regular Friday night stargazing sessions. Normally, we'd focus our attention on the sky outdoors, however, with an increase in the amount of cloud and rain at this time of the year as well as being close to Christmas, it seemed like a good excuse for some indoor activity as well.


1) Planetarium Shows
Our inflatable planetarium has been very popular at the Singapore Science Festival and other events over the past year or so. Now its time to bring it to the observatory.
Inside the dome you'll be taken an out of this world journey through the constellations of the night sky and the planets of the solar system. During the 25 minute show, a presenter will explain the details of the celestial wonders displayed above you.
Price:$5 per participant
Duration: 25 mins
Maximum capacity: 25 visitors per show
Floor seating with cushion
The is a dark enclosed environment not recommended for children below 3 years old.




2) Light Painting
Another favourite at science festival events. Inside a darkroom, you can choose a light and use it to draw/paint an invisible picture in front of a camera. Using a long exposure your light painting will be captured on a photograph, which is then printed for you to take home.

Price: $2 per go/photo
Light painting can be done individually or in groups of twos or threes. Only one photo is issued per two dollars.

video



3) Light Catcher 
This hands-on, model making activity involves using a variety of reflective and translucent material to capture light and create many colourful effects.
Price $2 per set


In addition to these we also have our free colouring cards and a small collection of reference books available, should the clouds refuse to move away.
Of course, our telescopes will still be open for free stargazing, once the sky is dark and clear enough.

Happy stargazing and Merry Christmas!

Wednesday, November 28, 2012

Venus and Saturn Conjunction

This week and next week there are a couple of nice planetary alignments.
On Tuesday 27th November, Venus and Saturn were in conjunction  meaning than Venus (the faster and closer of the two) moves in front of Saturn and begins to overtake it.


When viewed from Earth they appear very close together in the sky during the early morning (6am-7am). Each day moving further apart as Venus flies past Saturn, further away from Earth towards the other side of the Sun.

I missed the actual conjunction on Tuesday morning, it was rainy, but managed to wake up half an hour early this morning (Wed 28th Nov) to take a few photos.
Fortunately, it was very clear, apart from a bit of mist and hazy. I didn't have a large tripod handy so had to make do with a small portable one (which I got free at an IT fair). Had to hold it steady with my hands whilst lying down on the ground. Got a few curiosity looks from some passer by on their morning run.
The photo turned out alright apart from a slightly elongated shape to Venus and Saturn due to the movement of the tripod.
Venus (brightest) and Saturn (above) - 28th Nov 2012 6:15am - Singapore

Next week is Jupiter's turn to align with Earth, in what's called opposition, where it will be at it brightest, but not by much compared to how it looks this week.

Wednesday, November 14, 2012

1 night, 3 planets, 2 satellites, the Moon and stars!

Last weekend on the evening of  9th-10th Nov, there were lots of bright and interesting things up in the sky. Fortunately, the night was partially clear and I was ready with my camera to snap some photos.

First up was an Iridium Flare. These bright communication satellites only reflect sunlight for a few seconds at specific points in their low earth orbit (LEO). On Friday night 7:48pm we assembled the volunteers and visitors at our stargazing session together to witness the event.
Faint Iridium Flare - thin white line, centre, amidst the clouds - Friday 9th Nov 2012
This was my first attempt at photographing an Iridium flare. In my haste I didn't quite get the exposure and ISO setting correct, so it didn't turn out so bright but it was partially hidden by clouds also.


Next was Uranus. I've been trying to get a shot of this dim planet for more than a month now but the sky was always too bright and cloudy. Towards the end of last Friday's session, attempted to locate it in a clear patch of sky near the zenith. A bit of a challenge as our right ascension coordinates on our 1980's Pentax telescope controller are no longer working accurately. However, I was able to locate it in the finder with the aid starry night software and Google Sky Map.
Uranus - 9th Nov 2012 - Taken with Nikon D70s DSLR through 16" Cassegrain

Several visitors patiently waited until the the end of the session to catch a glimpse of Jupiter around 10pm.
Afterwards, I swapped the eyepiece for a T-Adapter and took a few shots. It was hard to get a sharp focus due to Jupiter's low altitude at the time (around 20degrees). It was nice to see the four Galilean Moons flanking Jupiter, with two on each side.
Jupiter - 9th Nov 2012 - taken using Nikon D70s DSLR through 6" refractor telescope.

Jupiter with Galilean Moons - from the top: Ganymede, Europa, Jupiter, Io, Callisto - 9th Nov 2012 - taken using Nikon D70s DSLR through 16" Cassegrain telescope.

Jupiter - 9th Nov - taken with Nikon D70s camera using 2x Barlow lens through 16" Cassegrain telescope.

Reaching home around 11:30pm, I set my alarm for 5am to see a bright ISS flyby.
At 5:30am (Sat 10th Nov) I was ready outside with my camera, tripod and the mosquitoes.
It took about 4 mins for the space station to go from SW to NNE, however I kept my exposures to 30 seconds as I was worried the background sky would become too bright if I'd opened to shutter for longer.
ISS travelling between constellations Canis Major (above) & Orion (below), towards Canis Minor (top).



Fully awake with a bunch of bright objects in the sky, I continued to take more photos for the next few hours.
Jupiter (bright object at the bottom) with Orion (centre), Sirius (top left) and Procyon (Canis Minor, top right)

Moon (top) and Venus (below) - 6:20am Sat 10th November - Singapore

Waning Crescent Moon


Finally, sunrise came and as I leave near Changi Airport, I also got a shot of some planes before the sun came up.
Out of focus "Solar Pillar" phenomenon before sunrise 6:40am Sat 10th November

Plane landing at sunrise 6:50am


The Sun - shortly after sunrise - 7:20am Sat 10th Nov

Thursday, November 1, 2012

November Night Sky

Halloween is over and November is here. As mentioned in my previous post, this is the time of year that Singapore experiences its earliest sunrise and sunset.

For the first half of November the Sun will rise at about 6:46am and set at 6:50pm. From now on, sunrise and sunset will gradually get later and later until around February 10th, where they reach their latest times of 7:17am and 7:21pm (in Singapore and other equatorial regions). Only half an hour different but it is noticeable  so enjoy those brighter morning this month.

Weather-wise, its still very rainy as we head further into the end of year rainy season. Although there are still some hot and sunny days here and there.
Here's a number of things can be seen on those occasional clear night.

The Moon

The best nights to observe the Moon at SCOB will be Friday 16th Nov (crescent Moon) & Friday 23rd Nov (Gibbous Moon).

Wednesday 28th November 2012, is the smallest Full Moon of the year, as this month's Full Moon coincides with the Moon's apogee or furthest distance from the Earth (roughly 406,364 km away).

However, the effect will be hard to notice as the size difference in the sky compared to other Full Moons will only be very slight. Although, I'm sure many photographic illusions will appear at this time to make the moon appear teeny-tiny.


Stars and constellations
Constellations in the early evenings of November are pretty dim. The brightest are located towards the North, the most obvious being the square shape of Pegasus and three bright stars forming the backbone of Andromeda (the Princess).

Located within this area are a few interesting objects:
1) Andromeda galaxy (M31) - one of the brightest and closest galaxies to our own Milky Way. Not such a great sight from Singapore, due to light pollution, but on a really clear night with no Moon, I've seen it as a  dim glow in our main 16inch telescope. (9th Nov and 30th Nov will probably the best Fridays to try this).
2) Gamma Andromedae - a bright double with a distinctive gold and blue colour pair of stars (when seen through telescopes).
3) The Triangulum - small constellation of three stars easily visible in binoculars and the naked eye.

Later in the evening towards midnight the bright constellations of Taurus and Orion begin to appear.

Planets
Uranus and Neptune are still around, high up in the sky, but they only appear as tiny faint dots.
Jupiter, one of the brightest planets in the sky, is visible just before 10pm. So we'll be aiming our telescopes towards Jupiter at the end of our Friday night stargazing sessions.



Thursday, October 25, 2012

Halloween in the tropics - an astronomical event

Next week is Halloween. This festival is normally associated with death and spook things but it also has an astronomical significance, just like alot of other seasonal holidays.

Halloween occurs on 31st October every year, which is in the middle of the season of Autumn or Fall in the Northern temperate regions of the Earth. During this time the leaves on many trees (so called "deciduous trees") start to turn brown and fall to the ground, in preparation for the approaching winter months.
I'd imagine that the disappearance of alot of the summer flora and fauna was one of the key influences for the "death" theme of Halloween, as at this time life simply seems to fade away, to be replaced by a cold, barren, frozen landscape.
A typical British street during winter - with leafless trees and frost or snow covering the ground.

These changes are mainly triggered by a reduction in the amount of sunlight, resulting in a lose of chlorophyll (the green stuff responsible for photosynthesis) in leaves.

Basically Halloween signifies the middle point between the Autumnal Equinox (22nd Sept - where night and day are equal in length) and the Northern Winter Solstice (21st Dec - the shortest daylight hours of the year).

Although we don't experience the same seasons here in tropical Singapore, there are a few  astronomical clues that can be observed around Halloween:

1) Early Sunrise/Sunset
If like me you wake up for work around 6:30am-6:45am, you may have noticed recently that the sky is already bright compared to a few months ago when at the same time it was still dark.
This is because on the day after Halloween (1st Nov) Singapore (and other tropical areas) experiences its earliest sunrise for the whole year. Sunrise on this day occurs at 6:46am compared to the latest sunrise of 7:17am on 10th Feb (incidentally close to Valentine's Day and Chinese New Year).
In the tropics, early sunrise also means early sunset. So if you get home around 7pm, over this next week, it should be almost dark as sunset on 1st Nov (and Halloween) is at 6:50pm.
All this is a result of the orientation of Earth's tilt relative to the Sun at this time of year.

9am Morning Sun during June  - Sun located towards North-east (on the left).
9am Morning Sun in October - Sun is slightly higher and more towards the South (right) than earlier in the year.

2) Southern Sun
During Equinox (22nd Sept) the Sun is directly level with the equator, which from Singapore, results in the Sun rising due East and setting due West, with the midday Sun directly overhead.
On December 21st (solstice) the Sun rises from its most southern point in the sky. Around Halloween the Sun will be halfway between these two positions. So the daytime sunlight will come from a slightly southern direction. Bad news for those with south-facing windows, as for the next few months you can expect more and more sunlight on that side of your house.

This effect can also be seen in the orientation of shadows on ground.
Back in June (close to northern solstice) the Sun was at its northern most point so shadows appear to point south.
12:30pm - Midday shadows in June (solstice) - shadow are long and point south (left).

During Equinox, shadows pointed more or less east and west as well as directly below our feet.
12:30pm - Midday shadows in September (Equinox)  -  shadows are short, gradually pointing west and east in the morning and afternoon.
Lunchtime shadows in September (Equinox) are directly  below our feet

Around Halloween shadows now point slightly north (i.e. opposite the Sun).
12pm - Midday Shadows in October (close to Halloween) - shadows point slight North (towards the right)
Of course Halloween has alot of other cultural and religious influences, but its timing is primarily astronomical in basis and represents one of the four so called "cross-quarter dates" that occur between solstice and equinox.


Being an astronomer in Singapore has its uses, sometimes to share these little tidbits of information with others whilst walking out for lunch, to pause for a few seconds in order to look around and observe the small occurrences of the Earth's daily wanderings through space before we ourselves resume going about our own daily life.

Thursday, October 11, 2012

October sky highlights (sounds like a movie review but its not)

I'm a bit late this month's stargazing guide as I've just come back off holiday.
Weather's been quite bad lately as we're entering the rainy season. If the sky clears up the Moon makes an appearance in the early evening during the last two weeks of the month.

Friday 19th October sees the Crescent Moon close to Mars and the constellation Scorpius. At the same time the red planet Mars will be close to its twin, the bright red star Antares.
Red in colour, it would be nice to see these two bright objects below the moon like a pair of eyes, however there'll be quite low to the ground so good clear skies are needed. 8pm is probably the best time to spot them, I'll try to have a camera ready.


Finally, as the bright planets Mars and Saturn disappear from view, faint planets Uranus and Neptune slowly rise in the east. Almost impossible to spot with the naked eye in our light polluted sky. We'll be aiming our telescopes in their direction every Friday over the next few months hoping to catch a glimpse.

As mentioned previously, Uranus and Neptune are incredibly tiny but quite nice and blue. I always feel a great sense of achievement every time I find them, especially without the aid of computerised GO-TO telescopes. A nice challenge, can't wait!