Stargazing on the green rooftop

Never underestimate the captivating power of a clear night sky. Since the last Sidewalk Astronomy at Yew Tee MRT station (check out our post here) (which attracted over 300 people in 2 hours), Scobbers headed out for an outreach event again last month. NIE’s Bachelor of Science Club (BSC) invited SCOB on our Facebook Page (Do like it if you haven't done so!) to conduct a stargazing session for the student teachers.

On 25th March 2014, Scobbers Alfred and Kin Guan brought starmaps (you can download them for free as well on SCS website) and a Celestron C8 telescope for the event. The venue was set at NTU’s School of Art, Design and Media (ADM) building. For those who have been there, the iconic curved rooftop is covered by grass patch completely. More importantly, the unobstructed view of the night sky was terrific. We were thrilled by the excellent choice of the stargazing spot.

Image Credit: NTU School of Art, Design and Media

At the start of the event, Kin Guan gave a short talk on the night sky to the audience who were enjoying pizzas at the same time. A tutorial on how to use the starmap was given as well as easy identification of stars and planets. After that, Alfred and Kin Guan manned the C8 telescope for viewing. We pointed out constellations using green laser pointers as well. At the end of the day, 50 student teachers enjoyed themselves and learnt one or two things about astronomy.

Scobber Alfred setting up the scope.

Alfred preparing the scope for viewing.

Scobber Kin Guan giving a brief introduction to the night sky.

Interested to have a sidewalk session for your club or school? Leave us a comment and we can arrange something together!

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.

June Solstice in Singapore

This week is June Solstice week, where the Sun reaches its most northerly point in the sky. Of course, this event is not due to the Sun's actual movement but instead the movement and tilt of Earth. Every year around 21st June, Earth's north pole points more towards the Sun than at any other time of year. This causes a number of significant effects here on Earth.

June Solstice signifies the start of summer in the northern parts of the Earth as well as the longest daylight hours for the whole year. At the same time, it also marks the start of winter and the shortest daylight hours in the southern hemisphere.
There's often a great deal of excitement and sometimes celebelation associated with solstice particularly in places like stonehenge in the UK, where crowds gather from sunrise (around 5am) to sunset (around 9:30pm). The stones themselves also mark the Sun's position at solstice.

Stonehenge - Credit: Pete Strasser - NASA.gov

In Singapore, the effects of solstice are a little harder to spot as near the equator the Sun's position varies only slightly throughout the year.
However, here are some of the signs to look out for in order to notice the solstice from 1 degree north of the equator:

1. Longest daylight hours and shortest night. As Singapore is technically in the northern hemisphere by 1 degree, we also experience the longest number of daylight hours for the year. How long? Exactly 12hours 11minutes 48seconds, from sunrise to sunset. Compare this to the shortest daylight hours of 12hours 3minutes 2seconds in December, the difference is only 8 minutes. Not much to celebrate about, but it is noticeable particularly if, like me, you find yourself reaching home around 7pm. Whilst walking home from the MRT station, bus stop or waiting for a ride, look up at the sky and see if it looks any brighter than usual. A slightly later sunset at 7:16pm should make the sky look brighter than at other times of the year.

Sunset/dusk in June - Longer daytime, later sunset, slightly brighter sky.

Sunset/dusk in April - slightly darker than in June.

2. Sunrise, Sunset and Northern Sun
If you're heading out to work or school around 7:30am or 8am, you may notice that the morning Sun is positioned slightly more to the left (i.e. North) than usual.

June morning Sun to the left (north) of the Science Centre entrance - After June 21st the morning Sun will gradually make its way south (towards the right)

After 21st June, take a look at the Sun every now and then over the next few months around 8am. You should find the Sun gradually moving more towards the right (i.e. south) every week, until it reaches the December solstice position on 21st December.
Similarly at sunset, the afternoon/evening Sun should be located more towards the right than usual. This can be a bit annoying if you happen to own a house, flat or condo with north-facing windows, thinking that you'll escape the brightness and heat of the afternoon/western Sun. Around June Solstice, you'll start to find what was once a nice shady spot is now lit by bright sunlight, as that north facing window is now tilted slightly towards the Sun for most of the day. Those with south-facing windows will experience the same thing in December.

3. Noontime Shadows
Between 12:30pm and 1:30pm, the Sun is at its highest point in the sky but as the June Sun is at its most northern point, midday shadows on the ground will be at their longest as compared to other times of year.

June Solstice Shadows - Longest noontime shadows. Shadows point South

Morning Shadows in June - Sun rises from north-east, shadows point south-west 

If you compare your shadow at midday over the next few months you should find it becoming gradually shorter and shorter until finally its directly below your feet around late September, when the Sun is directly overhead (Autumnal Equinox). Also, as the Sun is located towards the North, all the June shadows should point in the opposite direction towards the South.


All parts of the world, will experience the effects of solstice in one way or another, the most obvious being  in those parts furthest from the equator.In Singapore, the changes may be small, but the clues to spot them are all around us, we need only stop for a while and look around at the environment we live in.

There are a number of other times in year in which the Earth's tilt causes other seasonal effects, such as the the position of the Sun, daylight hours, sunrise, sunset, planet growth, animal migration and seasonal weather patterns. Some of these changes have even influenced the dates of well know holidays and celebrations such as May Day, Halloween, Mid-Autumn Festival, Christmas and Chinese New Year as the movement of objects like the Sun and Moon, have formed the basis of many calenders for thousands of years.
The world may be full of different cultures, but we all share the same sky.
Happy Solstice everyone!

Speed of Light Experiment

In between workshops, shows and other events, we find time to explore ideas for new programmes. This week, over lunch, scobbers Yong, Kin Guan and myself had a number of discussions about how to demonstrate the nature of waves, light polarisation, the doppler effect and the speed of light, the kind of things that we science educators get very excited about, well some more than others. It was even more exciting when we remembered a popular demonstration that uses a microwave oven to measure the speed of light. So, coming back to the office after lunch we decided to try it out.

First we needed to find something that can easily melt so we quickly procured some chocolate chips from........... somewhere. Next we headed for the microwave in the 3rd floor lab staffroom.
Having removed our lab attendant's lunch from the microwave, Yong gave the glass plate a wash and covered with the chocolate chips.

The next step was to remove the plate's base from inside the microwave so that the plate cannot spin.

This is the important part as the turning motion of the plate helps spread the microwaves around whatever it is you're cooking to allow for even heating. However, for this experiment we do not want an even distribution of heat, we need to identify where the hot spots of the microwaves are, so no rotation.

We also used some handy bottle caps to raise the plate above to central hole and to keep it level.

After the all important set up, it was time for action. Our non-rotating plate of chocolate chips was placed in the microwave and heated at FULL POWER for about 20 seconds.
And voila! It worked.

As you can see from the pictures above, there were six separate partially melted areas (i.e. the shiny bits). These areas, arranged in neat parallel rows, are the so called hot spots, receiving more heat than other areas. The reason for this is due to the fact that microwaves behave like.......waves, meaning that they form peaks (crests) and troughs, which are the regions where the intensity is at its greatest.

Microwaves are just one form of electromagnetic radiation, similar to light. However, microwaves are long enough for us to be able to measure them using a ruler.
Measuring the distance between two of the melted areas gives you the distance between one peak and one trough, which corresponds to half a wavelength.

In our experiment, this distance was about 0.065 metres (or 65mm). Multiplying this number by 2, we got a wavelength of 0.13 metres.
Wavelength x frequency = speed (velocity)
The frequency is usually printed on the back of the microwave. Our microwave's frequency was 2450 MHz (2450,000,000 Hertz).
Therefore 0.13 x  2450000000 = 318,500,000 metres per second.


We measured the distance between another pair of melted areas and got a second wavelength measurement of 0.12 metres. This gives a speed of 294,000,000 metres per second.
Taking the average between these two speeds, we measured the speed of light to be 306,250,000 metres per second.
The actual speed of light is approximately 300,000,000 metres per second.

Therefore, we declared this experiment a success! Our crude attempt at measuring the speed light turned out to be realtively close to the actual value, we were only out by about 6,000,000 metres per second (hmm, maybe it sounds better if I say by 2%).
There are many examples of this experiment on YouTube as well as other places. It can also be tried using, large bars of chocolates, cheese or marshmellows, although heating times may vary :)

Simple science in a kitchen, and the best part is that you can eat your experiment after you're done.

Astronaut Photography of Earth

Dear all, long time no see... It's been a busy start of the year for all of us at Science Centre, and we finally made it to March! The Science Centre Observatory will be open as usual tonight, and because it is the start of the 1 week school holidays, we are expecting a surge in visitors. Feel free to come and join us! Our Colour-Wall is reaching completion soon, and since a few weeks ago, visitors have been making their own sundials and bringing them home as souvenirs.

If you have always been a fan of our Omnitheatre movies, Forces of Nature is an upcoming movie all about natural hazards such as earthquakes, tornadoes and volcano eruptions. While doing a research on natural disasters, I came across a really cool website by NASA.

The Gateway to Astronaut Photography of Earth

Packed with 481,761 rare photographs from the International Space Station, you can search for any feature on Earth, and get a vast list of stunning photographs from their database.

A search for "volcanoes" gave me a list of beautiful volcano pictures, much like looking down on Earth from an aeroplane. A colleague searched for "Tokyo at night", and got this:

For those who love beautiful pictures, or anyone who needs a photo resource of the earth, this is definitely a webbie worth bookmarking.

An Amazing Visual Treat

Thanks for the recommendation, Terence! This video achieved 8766 five-star ratings on Youtube, and when watching it, I found myself holding my breath, 'cause it was simply awesome.

The Known Universe takes viewers from the Himalayas through our atmosphere and the inky black of space to the afterglow of the Big Bang. Every star, planet, and quasar seen in the film is possible because of the world's most complete four-dimensional map of the universe, the Digital Universe Atlas that is maintained and updated by astrophysicists at the American Museum of Natural History. The new film, created by the Museum, is part of an exhibition, Visions of the Cosmos: From the Milky Ocean to an Evolving Universe, at the Rubin Museum of Art in Manhattan through May 2010. For more information visit http://www.amnh.org/.

Water on the Moon - CONFIRMED!

Today's Google Logo above.

Water on the moon has all along been suspected but never proven. But scientists have recently CONFIRMED the presence of water on the moon! COOL.

Here is a short article from telegraph.co.uk:

What exactly has Nasa found?

The equivalent of 24 gallons of frozen water, mixed in with the rock and dust that was thrown into the air when a rocket was deliberately crashed into a crater near the Moon's south pole last month. It is far from the science fiction fantasy of an underground lake, but still pretty impressive for a satellite long dismissed as arid and dull.

Didn't we know there was water on the Moon already?

Scientists have long suspected that there was water on the Moon, but have struggled to prove it. The sensors on orbital craft have detected evidence of hydrogen on the lunar surface, but the quantities were tiny. A major breakthrough came last September, when India announced that its Chandrayaan-1 craft had detected that chemical reactions producing water are still taking place.

Where does the water come from?

No one is certain. One theory suggests that hydrogen released by the Sun in solar winds could have reacted with compounds containing oxygen in the Moon rock, producing tiny amounts of H20. Another explanation proposes that the water came from vapour produced when comets and meteors crashed into the Moon's surface.

What does this all mean?

Nasa has been so keen to find water on the Moon because it brings the dream of a permanent lunar base one step closer. If water exists in the quantities that Nasa now believes, it could be drunk by astronauts, turned into oxygen to make stations inhabitable and – most excitingly – converted into fuel. The Moon could then become the space equivalent of a service station – acting as a staging post for manned missions to Mars.

Today's Google logo shows this:

The Galileo's Telescope :)

Today's Google logo shows this:

And that means it is a special occasion, and you should be verrrrrrrry excited.

It is the 2009 Perseid meteor shower!

The name Perseid originates from the constellation Perseus which the meteoroids appear to come from. (The meteoroids do not actually come from Perseus. Perseus is made up of stars light years away, while these meteoroids are only miles away, passing through our atmosphere.) This meteor shower is an annual event which happens every year early August. The Earth passes through rock and dust fragments left behind by the comet Swift-Tuttle, and as these small particles collide with the Earth’s atmosphere, they burn-up, often creating a beautiful streak of light across the sky.


Can we see this meteor shower in Singapore? Andrew says yes☺. Face eastward tonight (slightly to the north) and look high up from 11pm to 5am, it is going to be a wonderous spectacle. But it would require a relatively clear sky and what you see may be affected by the brightness of the moon. As always, the darker the better. Depending on the sky conditions you may see about 10- 20 meteors per hour. The peak time for meteor showers is usually around 2am to 4am.

Note that you need just your naked eye to see the meteor shower, a pair of binos may come in useful if you have one. It is best to have a comfortable chair or mat that you can rest on and gaze at the sky for a few hours.


We wish you luck.

Check out NASA's article on Perseids here.
Source: IYA2009, Sky and Telescope

A short video of what you may see:

Good Morning!

Long time no blog, and I apologise >.< < >June school holidays brought us many many visitors and we are elated that there are so many people interested in Astronomy. Hope you guys come back soon! There are new and exciting things coming up in the Friday nights ahead, as you would be able to see on the "July Highlights" on your right that Andrew has updated. For those of you who want to see Mars, do check out "A Little Something For the Morning". For those of you who are excited about the upcoming Solar Eclipse, check out "Upcoming Events - Solar Eclipse". Thanks a lot Andrew!!!!!!!

While doing some research for our new space programmes, I came across this webbie by MSNBC. And I couldn't take my eyes off! The Month in Space showcases rare photographs related to Astronomy, and it archives 2 months back. So that's 60 eye candies to share with our beloved blog visitors. :D

Just a glimpse of what you'll see:

Go see it right now!
Meanwhile, what do you think of our blog? And which part of the Observatory did you enjoy the most? We certainly want to keep the Observatory a happy and warm place where the passion of Astronomy is shared. Do drop your comments or talk to us or share your knowledge with us via the tagboard on your right.

Thank you and have a good week ahead! See you on Friday :)

Why Isn't Pluto a Planet Anymore?

Hi, long time no see! I stumbled across this video on Youtube and I thought I must share it. Very often we get visitors asking us, "What has happened to Pluto? Why isn't it a planet anymore?"

Well the answer is, nothing has happened to Pluto to make it not a planet, it is actually we humans who decided Pluto should not be classified as a planet, but a dwarf planet instead.

Why? Check out this very very informative and cute video to find out. :)

Photoelectric effect and how it relates to the colour of stars

Photoelectric effect is the emission of electrons when light shines on a metallic surface. The emission of electron from this effect is called photoemission.

Materials such as metal will produce the photoelectric effect more readily. This is because the electrons in metals are free; they are only bonded lightly with its nucleus. That is the reasons why metals are good conductors (the electrons move when a voltage difference is placed across them) A collective movement of electrons is what we call “current”. Contrary to conventional thoughts, it is the movement of electrons or the negative charge that underlies the idea of what we consider “electricity” not +ve charge or protons.

When the photoelectric effect takes place, scientists can measure the electrons that are released by measuring the electrical voltage. They found out that it happens only with certain kinds of light. By doing further test, they discovered that what causes photoelectric effect is the frequency of light. The frequency of light also determines the colour of light that we see. Red colour is in the lower frequency and violet the highest frequency that our eyes can observe.

The higher the frequency, the more likely electrons will be emitted. The lower the frequency, the less likely photoelectric phenomenon will take place. It doesn’t matter how much power is used, you may use a thousand watts of low frequency light, but it would not cause the photoelectric effect to take place!

This has a really important implication, by discovering that energy is linked to light frequency. Increasing the intensity of light will produce more photons (or light) but it will not produce photoemission if the frequency is not high enough. The energy of the electrons emitted will also correspond to the energy or frequency of the light incident on the metallic surface: high frequency light will produce high energy electrons.

Conversely the energy of a system may be measure by the frequency of light it produces, a simple one is that produced by the Bunsen burner. The blue flame produced is actually hotter and energetic than the yellow flame. The same could be said for stars, the younger they are, the more energetic, as they age they will tend towards the lower frequency such as yellow and red.

Dark Adaptation of Our Eyes

To view objects in the sky which are sometimes dim, our eyes need to first adapt to darkness.

Dark adaptation takes time. The eye’s pupil expands to its maximum diameter in seconds after the lights go out. The main cause of dark adaptation, however, is chemical and not related to the size of the pupil. Over the first 5 to 10 minutes in the dark, cone cells in our eyes reach their maximum level of dark adaptation. But over the next 20-40 minutes our eyes can gain 2 or more magnitudes of sensitivity. - MIT

This often makes a difference!

Red flashlight, however, helps protect your night vision. The rod cells in our eyes are not sensitive to red light. Rod cells are those that helped our eyes gain 2 more magnitudes of sensitivity after dark adaptation as mentioned above. The lamps in SCOB are covered with a red film, and red pocket flashlights can be purchased from Astronomy shops to read sky maps with during star gazing.

So the next time you are gazing at objects in the sky - stars, planets, nebulae... Do not blind yourself with bright flashlights from cameras. They often leave white spots in front of your eyes which hinder your own vision! :)

Space Rocks!

Space rocks comes in many shapes, sizes and can be constitute of many various substances! Scientists believed that Space rocks may be the remains of a planet that was destroyed billions of years ago or that it could be the debris left over from the formation of the solar system. No one really knows...Perhaps one day one day we will have confirmation on which one is more correct. The reason why scientists believed that space rocks may once be part of a planet is that some of them can be entirely made up of Iron and other heavy metals which are usually found in the core of planets!

Most of the space rocks are found in orbit around the sun. That orbital path is called the Asteroid Belt the other name for space rocks floating out in space is also Asteroids, smaller space rocks are called Meteoroids.

Any space rocks that has a diameter smaller than 1.6km is called a Meteoroid.

The picture above is drawn with artistic license, so please take it up with the proper authorities.

Sometimes the orbital path of a space rock would fall outside the Asteroid belt and come closer to earth than usual. Sometimes the gravitational pull from Earth may pull it even closer, and sometimes the gravitational pull of it may even cause the poor space rock to fall onto the surface of Earth at such great speed that the rock may create a streak of fire forming a long tail. We call this phenomenon "shooting stars" or meteors, we never call them asters. Occasioanlly if the space rock is large enough, or is made of denser substances like Iron, they may survive the journey all the way from space and smack right into Earth forming a crater. The left over space rock that survived is called meteorite.

This is the artist's childlike impression of a particularly large shooting star.

Earth Hour 2009

Dear all! This is my 1st post on this blog! And although it's not going to be about astronomy, it's about something that affects everyone! (Drumroll....)
It's Earth Hour 2009! Today, 28th March 8.30pm -9.30pm!

Vote for Earth against global warming. And let your light switch be your vote.
Alright, it's 8.28pm now and I'm going to switch off my lights as soon as I finish this post!
Have you voted yet?