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Rise of the Harvest Moon

On the 15th day of the 8th lunar month, i.e., 8 September 2014, many in Asia will be enjoying mooncakes and parading lanterns at night in celebration of Mid-Autumn festival, an annual celebration for the year’s harvest. Parents and teachers will also share tales of Chang’e’s ascension to the full moon during this night. While under the moonlight, observe if there’s anything different about the moon. Does it seem to be bigger, brighter and fuller?

Photo credit: EarthSky
This is the rise of the Harvest Moon. 

No, it is still the same, loyal moon that shows up on most nights. So what’s so special about this moon you ask? The Harvest Moon is the full moon that appears nearest to the autumnal equinox, a day in September when the length of day and night is the same, i.e., 12 hours, all over the world. But what makes the Harvest Moon so special is its coincidental occurrence with the other rare astronomical phenomena.

On average, the moon rises about 50 minutes later each day. But when a full moon (aka Harvest Moon) occurs near the autumnal equinox, the moon rises quicker at about 30 to 35 minutes later daily for several days before and after the Harvest moon.

Photo credit: EarthSky
The narrow angle of the ecliptic causes the moon to rise farther north on the horizon on 
consecutive nights, resulting in the perception of a few full moons on consecutive nights.

In the northern hemisphere, the ecliptic, aka the moon’s elliptical orbital path, makes a narrow angle with the evening horizon around the time of autumn equinox. As a result, successive moonrises around the full Harvest Moon have shorter rising time, and are seen to rise farther up north.  The period between successive moonrises drops to a minimum, and thus seem as if there are several full moons for a few nights in a row. The full Harvest Moon will appear in the northern hemisphere on 9 September 2014. However, for countries at the equator such as Singapore, the Harvest Moon cannot be observed. One needs to be really up north or south of the Earth's equator in order to appreciate the extended moonlit nights.

So why name it the ‘Harvest Moon’ then? As it takes lesser time for the moon to rise during this period, the dark period between sunset and moonrise shortens. According to EarthSky, the name might have been of European origin as northern Europe is much closer to Arctic than to the tropics. For farmers, the earlier moonrise provided more light after sunset, enabling them to continue harvesting their crops. 

As for you, do look out for the big and bright full moon in the night sky this Mid-Autumn festival period. Have a Happy Mid-Autumn Festival and do join us for our special planetarium shows featuring stories about the Moon and many others, every Friday night from 5 September to 3 October 2014 (excluding 12 September).

For more event updates and astronomy buzz, like our Facebook page!

Solar Observation on Summer Solstice Week

When in Singapore, everyday feels like summer - mostly hot ( average of 24- 32°C) and humid. We do not experience the transition of the environment through the 4 different seasons. However, if you were in the northern part of this world, e.g. America, you would be looking forward to this weekend as Summer hits the region. During Summer, the warmest season of the year, the sun will stay up in the sky for longer, resulting in a longer day time and hotter days as compared to the rest of the year.

What happens during Summer Solstice?

The summer that people in the Northern region will be experiencing is a result of the Earth’s position in relation to the Sun. Happening from June to September, the hottest season begins with the Summer Solstice celestial event which happens around 21 June every year. The word 'solstice' comes from the latin words, sol (which means 'sun') and stitium (which means ' to stand still') as the sun appears to stop moving. On this day, the northern region will experience the longest day of the entire year.

Everyday, the Earth faithfully revolves around the Sun, as well as rotate about its own axis. As the Earth does not spin around a vertical axis, i.e., it has a tilted axis (23.4 degrees towards the plane of Earth’s orbit), the amount of Sunlight that reaches the different parts of the Earth changes as it orbits around the Sun. During this 3-month Summer period, the Earth’s axis tilts towards the Sun, and as a result, the northern hemisphere receives more direct sunlight rays than the southern hemisphere.  

Photo: BBC Science

Summer in America is Winter in Australia

While people in the Northern hemisphere are donning on their bathing suits and getting ready to hit the beach, people in the Southern hemisphere, such as Australia, are putting on extra layers to brace themselves for the chilly winter. As the northern hemisphere is tilted towards the Sun and receives more direct light, the Southern hemisphere, which is at  the opposite side, receives less sunlight and experiences shorter daytime. Hence, regions at the opposite poles experience extreme differences in weather and different seasons.

Meanwhile in the South...

View the Sun on International Sun Day!

Have you been avoiding direct eye contact with the Sun because your parents or teachers have told you the Sun’s bright rays are damaging to your eyes? They are definitely right! Staring at the sun for too long is damaging to your retina and may even cause partial blindness.

We know you are curious about how the Sun looks like (and itching to look at it even for just a few seconds!). Here’s your chance to view the Sun directly and safely on International SUN-Day, which is held on 22 June 2014, the Sunday nearest to the Summer Solstice. The Astronomical Society of Singapore (TASOS) will be setting up some specially outfitted telescopes for solar observation at the Observatory for public viewing. Through these modified telescopes, you will be able to observe sunspots, prominences as well as the sun’s corona.

So make this SUNday a meaningful one by joining us to marvel at the beauty of the big flaming star. Everyone’s invited!

SUN-Day Solar Observation

Date: 22 Jun 2014 (Sunday)

Time: 3.00pm - 6.00pm

Venue: Science Centre Singapore Observatory

Cost: FREE for everyone!

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!

With Dr Neil deGrasse Tyson & Ann Druyan

On 13^th and 14^th February 2014, Scobbers Danny and Kin Guan were invited by National Geographic Channel to follow Dr Neil deGrasse Tyson around in Singapore.

Yes, you heard it right. The sexiest astrophysicist in the world, the guy who made many kids cry by demoting Pluto to a dwarf planet, the frequent guest on The Daily Show and The Colbert Report, and the meme immortalized online.

Image Credit: knowyourmeme.com

He came to Singapore to promote his newest TV documentary series COSMOS: A Spacetime Odyssey. This 13-part series, combining drama, fantasy and stunning natural reality, is the follow-up of Carl Sagan’s classic COSMOS: A Personal Voyage produced thirty years ago. Covering a wide range of scientific topics such as the origin of life and the universe, Sagan did a terrific job in communicating science to a wide public audience. The programme has been broadcast in more than 60 countries and seen by over 500 million people.

Image Credit: Wikipedia

It was such a precious legacy left by Sagan to us. Since his death in 1996, his widow Ann Druyan has been trying to create a new version of the series. Together with Dr Tyson and Seth MacFarlane (yes, the Family Guy), she managed to secure funding and TV channel (Fox TV) for the show.

In Southeast Asia, the first episode “Standing Up In the Milky Way” will premiere on simulcast across National Geographic Channel (NGC), NGC HD, Nat Geo WILD, Nat Geo People, as well as FOX, FX, and FOXCRIME.  Danny and Kin Guan, along with other media representatives, had the privilege to watch it during the press conference and media preview on Thursday (13^th February) held at ArtScience Museum.

Image Credit: National Geographic Channel

Image Credit: National Geographic Channel

Free from the shackles of time and space, Neil tells us the story of humankind and universe in his signature Ship of the Imagination. We were all amazed by the stunning visual effects and the splendorous views. The concept of compressing the whole history of the universe into one year opens up our eyes and mind – Human is so insignificant when placed in such a long scale of time. This is what Neil calls a “Cosmic Year”. For example, in the last second of the Cosmic Year (31 December, 23:59:59), human firstly observed the Moon in telescope and landed on it (which spans 400 years in real time)!

Image Credit: National Geographic Channel

Ann Druyan pointed out that the major differences between the old and new series are the cinematic experience and elements of skepticism. She mentioned that one 9-minute scene where the viewers are plunged into the heart of Titan, Saturn’s largest Moon. She believes that this new addition to the series will surely amaze the generations and beyond.

Image Credit: National Geographic Channel

Image Credit: National Geographic Channel

When asked how the rise of social media affects the science education for young generation, Neil was not worried over the phenomenon. Being an avid user of Twitter having 1.6 million followers, he found that the social media is not distraction at all. On the contrary, the power of visual splendour and storytelling bestowed by social media is staggeringly huge and provides an uplifting force to the society.

The last question asked was on his wrestling stint in Harvard: If he chose the road not taken and became a wrestler, what would be his ring name? The answer, of course, is related to astronomy. One very special property about the Moon is that it always faces the Earth with the same side. This effect, called “tidal locking”, can be true in the other way too! When the Earth faces the Moon with the same side, the phenomenon is called “double tidal lock”. Voilà, that’s Neil’s ring name and signature move.

What a menacing move from Neil the wrestler! "Double Tidal Lock"
Image Credit: National Geographic Channel

For a more detailed Q & A, please check out the blog post (link) on Science Centre website written by Danny!

Cosmos: A Spacetime Odyssey premieres on 15th March, 10pm (SG time), on the National Geographic Channel (SingTel mio TV Ch. 201 & StarHub TV Ch. 411). Don’t miss it!

Image Credit: National Geographic Channel

Sidewalk Astronomy at Yew Tee

Last Friday (7th February 2014), Scobbers Alfred, Everlyne and Kin Guan showed the wonders of the night sky to the public in Yew Tee for the first time this year. This was a collaboration between Science Centre Singapore and Yew Tee RC Zone 10.

We brought our C8 Celestron telescope out and set the venue up with the help of RC volunteers. The venue was Yew Tee MRT Open Space (In between Yew Tee Square and Yew Tee Mall). (Google Street View)

Cloudy weather around 7pm on Friday. What could we see?

Scobbers having a briefing with RC volunteers.

Setting up the banner. 

We started the telescope viewing at 8pm and the queue was already forming:

Thanks to the clear sky (the clouds kindly made way for us), we were able to observe first quarter Moon (it's a half-lit moon from Earth's perspective) and Jupiter. Alfred manned the telescope and introduced some fun facts about Jupiter and Moon:

Everlyne interacted with the public in the queue and handed them Star Map. It is a handy tool to identify the objects in the night sky!

Look, a shooting star! (and what happened to Comet ISON?)

Our Solar System is an amazing place. There are a bunch of objects whizzing around the Sun including planets, asteroids and comets. Comets, often called "shooting stars", are very interesting. They are strikingly beautiful, relatively rare and worth studying.

Comet ISON, called the "Comet of the Century" on various media, has been a popular topic since its discovery on 21 September 2012. Below we explain some basic features of comets, illustrated with the example of Comet ISON.

What is a comet?

Great Comet of 1882.

In simple term, a comet is a dirty ice ball moving around the Sun. When passing close to the Sun, it evaporates and displays a thin cloud and sometimes a tail. In scientific terms, the ball is called nucleus and the cloud coma.

Originated from Kuiper belt or Oort cloud, a comet mainly consists of rock, dust, ice, and solid gases such as carbon dioxide and methane. Its dimensions are from few hundreds metres to few kilometres. 

Comet ISON: It is around 2 kilometres long according to Hubble Telescope observation. 

How do we name a comet?

Many naming systems have been used to name comets, therefore many comets have more than one name. 

Comets are named after the year of discovery...

Great Comet of 1680. Isaac Newton used it to verify Kepler's Laws.

Or after the names of discoverer...

Halley's Comet. Discovered and predicted by Edmond Halley, it can be seen every 76 years.

Or according to IAU (International Astronomical Union) system. Comets are designated by the year of the discovery, followed by a letter indicating the half-month, and a number indicating the order of discovery. Prefixes are used to describe the nature of the comet as well.

Comet ISON: Comet ISON was discovered in Russia by International Scientific Optical Network (ISON). Its formal name is C/2012 S1:

• C/ means that it is non-periodic. It is not likely to revisit the Solar System. Even if it comes back to the Sun next time, it will be another 400,000 years at least!
• 2012 denotes the year of discovery.
• S denotes the second half-month of September.
• 1 indicates it is the first comet discovered in that period.

What is the fate of a comet?

A comet can end up in very drastically different outcomes. The possible fates are:

• It comes back regularly, for example Halley's comet (period of 76 years).

The orbit of Halley's comet. The next visit is in 2024.

• The nucleus evaporates by the Sun's immense heat and radiation. The comet is said to fade or extinct. 

3552 Don Quixote.

• The nucleus may break up under the Sun's gravity or radiation. The remnants are still spectacular.

Breaking up of 73P/Schwassmann-Wachmann in 1995. This animation covers three days.

• It may fall into the Sun or smash into another planet. Comet Shoemaker-Levy broke up and collided with Jupiter in July 1994.

The brown spots indicate the crash sites of Comet Shoemaker-Levy on Jupiter in 1994.

Comet ISON: According to NASA Comet ISON Observing Campaign, it is very likely that Comet ISON does not survive the trip. Most of the nucleus has been disintegrated by the Sun's gravity pull and intense radiation. All hopes are not lost yet, as a very diffused remnant emerged after the passage. The following short clip shows the time-lapsed images on the NASA STEREO spacecraft. 

(Big animated gif, please be patient... it is worth it!)

We may have been denied the opportunity to observe a bright comet in the night sky, but the scientific data collected is highly valuable. Scientists will know more about the behaviour of comets when they are very near to the Sun, and are able to predict such comets (called Sungrazing comets) better in the future. 

Reference:

1. http://hubblesite.org/hubble_discoveries/comet_ison/blogs/measuring-the-size-of-ison-s-nucleus-point-spread-function
2. http://www.isoncampaign.org/karl/a-trail-of-questions

Halloween Special: Spirits in Space

It's a spooky halloween! Pictured above is an eerie nebula (SH2-136) that is
located about 1,200 light years away from us.
Photo credit: Adam Block, NOAO, AURA, NSF

If you have watched the recent sci-fi space movie, ‘Gravity’ (starring George Clooney and Sandra Bullock), you would have realised the extremely risky nature of space expeditions. When things go seriously wrong up there, death is almost inevitable.

For the Celtic people who lived 2000 years ago, Halloween falls on the eve of their new year, which happens on 1 November. On Halloween (31 October), it is believed that the boundary between this world and the next becomes unclear. This is when the ghosts of the dead start to return to earth.  As we prepare to dress up in our spookiest costumes this Halloween night, let us take the time to remember the heroes who have sacrificed their lives up in space...

Before Neil Armstrong became the first human to conquer the moon, there had been hundreds of animals that were sacrificed in the name of space exploration. Animals such as monkeys, chimpanzees, dogs, mice and other animals were used as test subjects in space to analyse the effects of space environment such as microgravity and radiation exposure on human during spaceflight.

Laika, the space dog, was the first animal in space. Unfortunately,
she never return as a re-entry plan had not been worked out.
Photo credit: NASA

Unfortunately, the earlier designs for spacecraft construction were still in the experimental phase. As a result, many animals that were sent for spaceflights died from starvation or dehydration during flight and in explosions while on board the shuttle. In some cases, the spacecraft in which the animals flew in were never recovered. This has led to speculations of abandoned ships that might be drifting in orbit together with their animal astronauts.

It is not just animal deaths that happened during space travels. In 1971, three Soviet crew members of the Soyuz 11 spacecraft, Georgi Dobrovolski, Viktor Patsayev and Vladislav had died in space as a result of space decompression during preparations for re-entry. Technically speaking, these are the only human fatalities that occurred in space (100km above sea level) so far.

The unfortunate crew members (from left to right: Georgi Dobrovolski, Viktor Patsayev and Vladislav Volko)
of Soyuz 11 were the first men to occupy the world's first space station.
Photo credit: Joachim Becker/ SpaceFacts

Thanks to the sacrifices of these animals, astronomers are now able to better understand the requirements of bringing a living being into space and also what lies in the universe out there. So the next time you wish upon a shooting star or wonder what that mysterious looking object in the night sky may be, remember that there is more than meets the eye...

Happy Belated Mid Autumn Festival!

Scobbers were so busy that we forgot that Mid Autumn Festival has past! Other than filling ourselves with mooncakes and playing with sparklers, we found out some amazing facts about the Moon that you might not know.

1. The Moon was created in a huge impact event by a Mars-like object

Artist's Impression of Giant Impact event (Source: Wikipedia)

Termed as "Giant Impact Hypothesis", most scientists think that the Moon was formed after a great collision between the Earth and a Mars-sized object 4.5 billion years ago. It explains why the Earth and the Moon spin in similar ways. Scientists also did some calculations to show that if the post-impact Earth revolves in a 2-hour period, i.e. a day is 2 hours instead of 24 hours, we can explain some of the observations.

After the direct impact, the cores of the Mars-sized object and the young Earth fused. The collision made the post-impact Earth spin so fast that a significant portion of the Earth's mass was ejected to form the Moon. By the conservation of angular momentum (a quantity to describe an object's rotation), the Earth-Moon system has similar spin directions.

Also, if the Moon was created from the Earth's material we can explain the fact that the Earth and the Moon have similar chemical compositions. For example the isotopes of oxygen and titanium were found to have identical ratios in both lunar and terrestrial rocks.

The Mars-like object is commonly known as Theia. In Greek myth, Theia is a titan who gave birth to Selene the Moon, Helios the Sun and Eos the Dawn. That's why we use Selen- (or lunar) and Helio- to describe stuff related to the Moon and the Sun respectively.

2. We are always looking at the same side of the Moon

Near side of the Moon (Source: Wikipedia)

Far side of the Moon (Source: Wikipedia)

Readers may have known this fact a long time ago. The "dark" side of the Moon has also been depicted in movie as well. Of course, there are neither giant robots nor military bases located at the far side of the Moon, as shown in the NASA Astronomy Picture of the Day on 16 September 2013. (Direct YouTube link)

There is nothing hidden behind the Moon as shown in photos taken by lunar probes. There are only craters at the far side of the Moon (the side that is not facing us). On the other hand, the near side of the Moon (the side that is facing us) has more interesting features. Apart from the craters there are valleys, mountains and maria (meaning Sea in Latin). Maria appear dark as they mainly contain iron compounds that are less reflective. People in ancient times made up stories for the observed patterns, such as the Moon rabbit legend in Chinese culture. Do you see it in the following picture?

Did you see the Moon Rabbit? (Source: Wikipedia)

Regarding why the Moon always faces with the same side, we need to know how gravity works. Every massive object in the universe attracts each other with a force called gravity. For instance, an apple drops to the ground due to the Earth's gravity (the apple also attracts the Earth, but the effect is very negligible due to the Earth's much larger mass). The strength of the gravity depends on the distance between two objects, so in this case the near side is more attracted than the far side is, making the Moon face towards the Earth with only one side. This effect is called "Tidal Locking".

3. One day, we will lose the Moon

The Moon exerts a gravitational force on the Earth (and vice versa), pulling the water nearer to itself and causing high tide on the Earth. As the Earth rotates underneath the water (we can imagine Earth being a solid rocky ball covered by water), it tugs the tides and loses some of the rotational energy. As a result, the Moon picks up some of the energy and then speeds up, ascending from its orbit. On average, the distance between the Earth and the Moon increases by around 4 cm every year.

It has an interesting side effect: as the Earth loses rotational energy it will rotate slower and slower. The length of a day will increase as a result, amounting to 2 millisecond per century. Wish to have 48 hours per day? Perhaps if you're still around after 4 billion years!

Reference:

1. Wikipedia. Moon. Retrieved 20 September 2013, from http://en.wikipedia.org/wiki/Moon
2. Geology 5835 - The Moon - Fall 2006. University of Colorado Boulder. Retrieved 20 September 2013, from http://lasp.colorado.edu/life/GEOL5835/Moon_presentation_19Sept.pdf
3. A New Model for the Origin of the Moon. Harvard University. Retrieved 24 September 2013, from http://www.fas.harvard.edu/~planets/sstewart/Moon.html
4. M. Ćuk, S.T. Stewart (2012). Making the Moon from a Fast-Spinning Earth: A Giant Impact Followed by Resonant Despinning. Science Vol. 338 no. 6110 pp. 1047-1052.