Aurora: The celestial
Latest Updates on
Did men really land on
Astronomy at Home
James Webb Space
An inside look
Monthly Newsletter of
Chief Editor : Sachin Bahmba
Editors: Amit Verma &
Equinox or Equilux?
That’s the Big Q.
By C B Devgun
S No Topic Page No.
1 Universe In The School News 3
2 Blog : James Webb Space Telescope – An inside look 6
3 Events News 9
4 Astrophotography 13
5 Sky this month 17
6 School In Focus 19
7 Cover Story: Aurora: The celestial light curtains 22
8 Astroinquisites: Did men really land on the moon? 25
9 Guest Article: Equinox or Equilux? That’s the Big Q.
By C B Devgun, President, SPACE
10 Astronomy at Home : Shadow Dance 28
11 Astrotourism – Bonjour!!!! 32
12 Astroport – Sariska 33
13 SPACE is Hiring – Apply Now! 34
UNIVERSE IN THE SCHOOL NEWS
CENTRE FOR STUDENT EXCELLENCE PROGRAMME
Students and SPACE
Educator during the
Students participating in „balloon car‟
Student volunteer and Educator
demonstrating the working of
National Science Day at Step By Step, Noida on 4th March, 2014
SPACE EXPLORERS WORKSHOPS
SPACE conducted a wide variety of hands-on fun astronomy workshops at
various schools in Delhi:
Students learning the
construction of rockets
2. Rocket - A space vehicle workshop at Amity International School on 24th February, 2014
Students making their own rockets
1. Air Rocketry workshops at Bluebells International School on 7th March, 2014
Students learning about the
Students learn about air pressure Students make their own rockets
and get ready for launch
Students launch their rocket
and Winners of the competition
To Have Fun With Astronomy
& For UITS Updates
3. Astronomy Day at SUNCITY
SCHOOL on 28th February, 2014
4. Astronomy Day at DPS
International, Saket on
24th February, 2014
5. Astronomy Day at Srijan
School on 26th February,
them in their kit
JAMES WEBB SPACE TELESCOPE – AN INSIDE LOOK
Telescopes in space are the next big thing in the field of astronomy to get unresolved answers about our
mystical universe. In 1946, Lyman Spitzer, a professor and researcher at Yale University, argued that a space
telescope would offer great advantages over ground-based observatories. His paper, “Astronomical Advantages
of an Extra-Terrestrial Observatory”, explained that the Earth's atmosphere blurs and distorts light coming from
stars. Even the most precise and advanced telescopes on the ground cannot escape this phenomenon, but a
telescope in orbit can. Furthermore, the atmosphere blocks X-rays emitted from high-temperature phenomena
in stars and other objects, so they cannot be detected by instruments on the Earth's surface. A space telescope
would also allow scientists to accurately measure these emissions as well.
After many discussion and meetings, almost after half a decade the first space telescope was successfully
placed in orbit in 1990, the famous Hubble Space Telescope. It will be soon replaced by its successor, James
Webb Space Telescope (JWST), yet another achievement in this field.
JSWT, originated as the Next Generation Space Telescope (NGST) in 1996, based on generic planning for
Hubble successor in 1993. It was renamed in 2002 after NASA's second administrator James E. Webb (1906–
1992), noted for his role in the Apollo programme and establishing scientific research as a core NASA activity.
Address in Space
JSWT will not orbit the Earth, instead it will
sit at the Earth-sun L2 Lagrange point, 1.5
million km away! As Hubble is in Earth’s
orbit, it could be launched into space by the
space shuttle. Webb will be launched on an
Ariane 5 rocket and because it won't be in
the Earth’s orbit, it is not designed to be
serviced by the shuttle.
At the L2 point Webb's solar shield will block the light from the sun, Earth, and Moon. This will help Webb stay
cool, which is very important for an infrared telescope.
Goals of JWST
The James Webb Space Telescope will be a giant leap forward in our quest to understand the Universe and our
origins. The Webb will examine every phase of cosmic history: from the first luminous glows after the Big Bang
to the formation of galaxies, stars, and planets to the evolution of our own solar system. The science goals for
the Webb can be grouped into four themes:
The End of the Dark Ages: First Light and Re-ionization seeks to identify the first bright objects that formed in the early
Universe, and follow the ionization history.
Assembly of Galaxies will determine how galaxies and dark matter, including gas, stars, metals, physical structures
(like spiral arms) and active nuclei evolved to the present day.
The Birth of Stars and Protoplanetary Systems focuses on birth and early development of stars and formation
Planetary Systems and the Origins of Life studies the physical and chemical properties of solar systems (including our
own) and where the building blocks of life may be present.
Instruments to achieve these goals
JSWT will observe primarily in the infrared
and will have four science instruments to
capture images and spectra of astronomical
objects. These instruments will provide
wavelength coverage from 0.6 to 28
micrometers (or "microns"; 1 micron is 1.0 x
JSWT will have a 6.5 metre
diameter primary mirror, which
would give it a much larger
collecting area than the mirrors
available on the current
generation of space telescopes.
Hubble's mirror is smaller with
2.4 metres in diameter and its
collecting area is 4.5 m2, giving
Webb around 7 times more
The infrared part of the electromagnetic spectrum goes from about 0.75 microns to a few hundred microns. This
means that Webb's instruments will work primarily in the infrared range of the electromagnetic spectrum, with some
capability in the visible range (in particular in the red and up to the yellow part of the visible spectrum).
The instruments on Hubble can observe a small portion of the infrared spectrum from 0.8 to 2.5 microns, but its
primary capabilities are in the ultra-violet and visible parts of the spectrum from 0.1 to 0.8 microns.
Why are infrared observations important to astronomy? Stars and planets that have just begun to form lie hidden
behind cocoons of dust that absorb visible light. (The same is true for the centre of our galaxy.) However, infrared
light emitted by these regions can reveal what is inside.
Hubble is 13.2 meters (43.5 ft.) long
and its maximum diameter is 4.2
meters (14 ft.) It is about the size of
a large tractor-trailer truck.
By contrast, Webb's
sunshield is about 22
meters by 12 meters (69.5
ft x 46.5 ft). It's almost as
big as a Boeing 737
How different it is?
The full-scale model is assembled on the lawn
at Goddard Space Flight Center, and displayed
during September 19 - 25 2005. The Webb
Telescope team took a group photo with it.
Seeing the people gathered next to it shows
its scale nicely.
By Neeraj Ladia
For other upcoming
SPACE Foundation with The Russian Centre of Science and Culture co-organised the 80th birth anniversary
of Yuri Gagarin (the first human to journey into outer space) and the 30th anniversary of Russian- Indian
joint space flight on 19th March’14 at The Russian Centre of Science and Culture, Feroze Shah Road, New
Delhi. The event started with the lighting of Lamp by the distinguished guests of the evening, followed by a
briefing on the event by Miss Anastasia V. Khokhlova, Head of Cultural and Information department at The
Russian Centre of Science and Culture. In this connection a photo exhibition was inaugurated – “Yuri
Gagarin- the first planet cosmonaut”. Later on various speakers expressed their views on the occasion.
SPACE Foundation President, Mr. C B Devgun shared his experience on SPACE initiative of Eclipse
Chasing in Novosivirsk, the capital of Siberia and said that, as human being started venturing into space,
we moved towards the advancement of Technology. He further talked about the achievements made by Yuri
Gagarin, the 1st Indo-Russian space flight, and Rakesh Sharma, the first Indian to travel in space and in 1st
Indian space flight and India space programme.
SPACE Technology & Education Pvt Ltd`
SPACE celebrated vernal equinox with students by measuring
the Earth’s circumference at Jantar Mantar on 20th March, 2014
On 20th March, 2014, SPACE celebrated vernal equinox by measuring the
circumference of the Earth, using Eratosthenes experiment, with its associated
students and conducting a walk at Jantar Mantar.
About 55 school students from class VI to VIII participated. 11 schools from
Delhi & NCR participated, including Bal Bharti Public School - Rajendra Nagar,
Indraprastha International School - Dwarka, GD Goenka Public School-Rohini,
Sachdeva Public school - Rohini, Amity International School – Pushp Vihar,
Gurgaon, Noida, Saket and Vasundhara, Chinmaya Vidyalaya – Vasant Vihar,
Navy Children School – Chanakyapuri.
Most of the participating schools achieved more than 90% accuracy in their
This year, SPACE also participated in an international activity – „The Eratosthenes Experiment 2014‟ which is organized in
the framework of the Open Discovery Space Project, an educational outreach programme based in Europe. Under
this, students from schools across the world measured the Earth‟s circumference by performing the experiment of
Eratosthenes. They partnered with cities along the same longitude, shared the data and made the calculation jointly with
With the help of experts at SPACE the students replicated this experiment wherein they used the shadows cast by the sun
to calculate the circumference. The participants were also taken on a guided walk around Jantar Mantar where they learnt
about the usage of the ancient instruments.
Ms. V. R. Geetha, a student co-ordinator from Bal Bharti Public School, Rajendra Nagar said, “Session was well
conducted by SPACE group members. The working of various yantras was well explained by SPACE educators. This is
nice way to popularize hands-on science and promote learning in an informal atmosphere as a group activity. “
PAST EVENT – Project Paridhi SPACE Educator Abhinav explaining the
Eratosthenes experiment to the students
at Jantar Mantar. Click here for more
During the month of April, SPACE will
be celebrating Global Astronomy Month
2014 (GAM) with its client schools.
Organized by Astronomers Without
Borders (AWB) every year, GAM is the
world's largest global celebration of
astronomy. It brings new opportunities,
and brings enthusiasts together
worldwide, celebrating AWB‟s motto,
One People, One Sky.
Out of the gamut of activities that AWB proposes this year, we have selected six activities for our client schools. The
activity reports sent by schools to us will be further sent to GAM/AWB. The activities suggested by SPACE are:
Solar Observation - April 25th
Mars Observation - 11th April
Vesta Watch - 10th April
International Earth and Sky Photo Contest - 10th March to 24th April
Globe at Night – 20th to 29th April
Astropoetry Contest - 1 st April to 1st May
This year we are also celebrating the 30th anniversary of the first flight of an Indian into space. On 2nd April, 1984,
Rakesh Sharma became the first Indian cosmonaut to venture into space, as part of the a joint programme between
Indian Space Research Organisation (ISRO) and the Soviet Intercosmos Space programme.
To commemorate this achievement, SPACE invites messages from its associated teachers and students for Rakesh
Sharma, ISRO, Sonia Gandhi and the Russian Ambassador to India. The best messages would be selected by us and
presented along with the name of the sender to the intended audience.
To leave your messages, please visit the link: Message Form
For more details, visit http://space-india.com/gam.html
All India Asteroid Search Campaign - 2014 will be organized by SPACE for its associated students in
April. It is proud to be able to bring this campaign to the Indian students for the fifth time
The campaign is conducted in collaboration with International Astronomical Search Collaboration
(IASC, Hardin-Simmons University, Texas, USA). SPACE is the coordinator for this highly recognized
programme in India.
Under this project, the University offers the participants exclusive access to images taken by 24”
telescope and 32” telescope positioned in Astronomical Research Institute (ARI) Observatory, USA.
Participants then download these images and analyze the data with specialized software provided
during training to search for asteroids. Objects reported by students could be potential discoveries. All
observations contribute to the Near Earth Object (NEO) data compiled by NASA and Jet Propulsion
The campaign begins on 29th April. For details, visit http://space-india.com/aiasc.html
Astrophotography is a specialized type of photography that entails
recording images of astronomical objects and large areas of the night sky.
A S T R O P H O T O G R A P H Y
PHOTO 1 : ORION NEBULA IN H ALPHA FILTER
By C B Devgun, President, SPACE
Imaging through hydrogen alpha filters can bring remarkable enhancement to objects in the hydrogen-alpha
line. Most of the gas in space is made of hydrogen. When the hot, energetic, ultra-violet light from young stars hits
the hydrogen atoms, it strips off electrons. This forms a plasma that glows and emits light as the electrons and
atoms recombine and give off light at particular, specific wavelengths. The visible portion of the electromagnetic
spectrum ranges from approximately 400 nm to 700 nm. The strongest emission wavelength in a hydrogen nebula is
in the deep red part of the spectrum known as the hydrogen-alpha line.
Location: Mayhill, New
Camera: SBIG STL-11000M
with H-alpha filter
f/5.0 astrograph (T14
Focal Length: 530mm
Exposure Time: 300 sec * 4
Processing Software Used:
MaxIm DL, Adobe
PHOTO 2 : A NIGHT AT WORK
By Rishabh Jain, Educator, SPACE
Students ( near Bonfire ) and
Educators rewind after an
overnight observation during the
Messier Marathon weekend. The
summer arm of the Milkyway
Galaxy can be seen above the
Camera: Canon 6D
Lens: Tokina 11-16/2.8
Focal Length: 16mm
Sensitivity (ISO): 5000
Exposure Time: 30 sec.
Processing Software Used: DPP,
Adobe LR and PS
Sun rising on the day vernal (spring)
Instrument Used ( issued from
Camera: Canon 1100D
Lens: EFS 18-55
Focal Length: 55
Sensitivity (ISO): 200
Exposure Time: 1/200 sec.
Processing Software Used: Adobe
PHOTO 3 : SUN RISING ON THE VERNAL (SPRING) EQUINOX!!!
By Neeraj Ladia, Educator, SPACE
Photo 4: A FOALA
By Aanchal Tandon, Educator, SPACE
*Astroport is SPACE's new sky observation facility cum research centre at Sariska, Rajasthan, India
Andromeda Galaxy - Our
galactic neighbor is a spiral
galaxy approximately 2.5
ms) from Earth in the Andromeda
constellation. It contains One
TRILLION (1012) stars, at least
twice the number of stars in the
Milky Way galaxy.
This is the farthest object that we
can see with unaided eyes.
About 5 billion years from now,
our home galaxy – The Milkyway
and the Andromeda Galaxy will
merge to form a newer bigger
Instrument Used: Camera body: stCanon 1100D (Issued from SPACE )
Lens: 50mm/1.8 ( borrowed from Rishabh Jain | SPACE)
Location: Astroport, Rajasthan
Specifications: Focal Length: 50mm
Sensitivity: ISO 800
Exposure: 6 sec * 50
Stacking software used: DSS
Processing software used: Adobe PS
SKY THIS MONTH Stay updated about the events of the sky this month
Evening ( Dusk )
North - Cassiopeia, Ursa Major, Ursa Minor
East - Leo, Bootes, Corvus, Crater
West - Aries, Perseus, Taurus, Auriga, Gemini
South - Canis Major,
Zenith - Cancer
North - Ursa Minor , Ursa Major
East - Lyra, Corona Borealis, Bootes,
West - Cancer, Leo, Gemini
South - Libra, Corvus, Crater, Virgo
Zenith - Leo, Cancer
Morning ( Dawn )
North - Ursa Minor, Ursa Major,
East - Cygnus, Pegasus,
West - Bootes, Virgo, Corona
South - Scorpius, Saggitarius
Zenith - Hercules, Lyra
Moon Phases, April 2014
Last Quarter – April 3, 4:36
New Moon – April 10, 9:35
First Quarter – April 18, 12:31
Full Moon – April 25, 19:57
All timings follow Universal
Time (UT) standard
SCHOOL IN FOCUS
Sachdeva Public School, Rohini
Sachdeva Public School, Rohini established in April 1992 is a recognized School affiliated to
C.B.S.E., governed by the rules, regulations and curriculum of C.B.S.E. and is run under the aegis of
the “Shri Laxman Dass Sachdeva Memorial Educational Society(Regd.)” Under the brilliant
guidance of Chairman Sh. S.K. Sachdeva, the school aims to achieve to perfection its fundamental
motive of moulding the growing generation of the nation, through impeccable training in education, as
well as environment.
Principal, Dr. (Mrs) Ravija Prakash aptly summarizes the futuristic vision of the school through her
message to the students and parents,” We have stepped into a world where the horizons are
unlimited. At one end of the spectrum is nano technology where the entire communication system
proposes to be of the size of an air molecule; and at the other are the new frontiers vanquished in
SPACE has been associated with Sachdeva Public School since 2008 and has had a very good
astronomical relationship. The students have always shown a lot of interest and enthusiasm and have
even pursued the subject till Module-3.
“The exploration of the cosmos is a voyage of self
discovery”. The universe has infinite horizons and a
journey into space, opens unending marvel for students
to unlock some of its greatest secrets.
Milky way is quite fascinating and its incredible mysteries are
yet to be unravelled. I hope that the journey of our students
into these realms will provide the budding astronomers with
an insight into the vast field that is astronomy.
Message from the Director, Sachdeva Public School, Rohini
Messages from Club Coordinators
“It is astonishing how short
a time it takes for something
wonderful to happen”. In our
universe, a plethora of enthralling
events are occurring some of
which are being taught to our
students in the Astronomy Club.
It is just the start of a never
ending study of this enigmatic
“The study of Astronomy
compels the soul to look
upwards and lead us from this
world to another.” Exploring
the outer realms of the vast
universe is like hurling oneself
into the undiscovered. This
club has provided the students
a true manifestation of the
Ms. Aditi Sen Gupta Ms. Manisha Shokeen
Director, Mr. Sanjay Sachdeva
Students with Club Coordinators
at Jantar Mantar for Project
Paridhi on 20th March,2014
Students showing the comet
made by them in Comet
making club session
SPACE Educator guiding the
students to perform the
Students viewing sun through pin
hole projector made by them
Students showing their elation
after receiving the Astronomy
Telescopic observation by students
and teachers during Evening
Observation session in school
Aurora: The celestial light curtains
After having been associated with over 70 schools in our long journey of popularizing science and
Astronomy, we thought of getting in touch with some of our students and asking them how Astronomy
and SPACE have impacted their lives. This is what one of them, Ambar Prasad, Class XII of Amity
International School, Noida, had to say.
My family planned to visit Iceland in late 2009 after my Astronomy
teacher told me about the incoming Coronal Mass Ejection and the
effect it would have on the Aurora Borealis. And, in March 2012, we
landed at Reykjavik Airport, Iceland. The solar activity was predicted to
be ideal. Highly optimistic, all of us, my father, mother, brother and I,
drove around the empty roads of this tiny island nation, looking for
anything that resembled bright green lights. Clouds, the greatest enemy
of a star gazer, soon struck. We would get excited at any sign of a
luminous haze, but which turned out to be mostly city light pollution.
On the eighth night, with the weather on our side, I finally noticed a faint
haze. I went out with my tripod and camera, thinking that in real life the
photos were a result of trick photography. We were heading back, everyone
half asleep, except for my father who was on the wheels. My brother
pointed two mongooses running across the road and my mother turned
back to try and spot them. All of a sudden, she screamed and the car
screeched to a halt. Behind us, going unnoticed, was the greatest light
show on the Earth.
Bright green columns of light emerged from the clear, dark sky. The green
flowing light curtains illuminated the entire snowy landscape. The Arctic
winds were blowing fast enough to shake our car. Soon I found my tripod in
mid air, flying away from me; I caught it a few metres away. After a few
photos, we couldn‟t stay outside and retreated to the car.
In the October of 2013, my parents decided that they hadn‟t seen enough of
the Aurora just yet. With the end of the 11-year solar cycle, March 2014 was
our last chance. Early that month we landed in Tromso. This time we were
prepared with a better camera, heavier tripod, better equipment and our
eyes knew what they had to look for.
Our best chance was on the night we landed, equipped with coffee to
counter the jet lag, we had planned to stay up all night. Clear skies, again,
was scarce but, I pointed out the famous Orion to my father, who made me
turn my head to see a bright green Aurora in the sky. In the middle of the
runway, I started to take photos, and just gazed at the lights. If we could see
it from a brightly lit airport over one of the biggest cities in the north, we‟ll
see it everywhere. We were wrong.
So we drove out. Clouds had filled up the sky, with few clear patches. And
just like in Iceland, we‟d left the camera in the hotel. Only this time we didn‟t
see any activity that night.
During the last few nights that we were there, the weather worsened. We
drove out in a blizzard, countering heavy snow and rainfall. The solar activity
had decreased, with the band of the Aurora barely in the range of Tromso
and then gone completely, contrary to the prediction.
On our last day, we drove up to a lake in Sweden, as the weather
conditions were supposed to be more favourable than in Tromso. We
started to drive out at 11 in the morning, in a four-hour drive. My brother
had an early flight the next morning, so we knew that we would have to
drive all night back. We reached the lake early in the evening. The weather
didn‟t seem all that better with as much the cloud cover as in Tromso. We
left from the lake, onwards to a city with better conditions. On our way, it
started snowing heavily, and then, suddenly, the sky became crystal clear.
The moon light reflecting off the snow filled the landscape. A few kilometres
ahead, the blizzard started again. Conditions in the city became terrible.
We all headed back, disappointed.
We reached that clear spot again, but the solar activity wasn‟t on our side. I
took a few photos of the landscape so that I don‟t go home empty-handed.
We were out of time, and I went out to pack up my camera, when my mom
pointed out a very distinct green haze. I screamed with joy when I saw the
preview, a bright green band among the clouds. It was a very dull and faint
Aurora, but the photos came out great anyway. And, as a proof that all
Aurora is accompanied with a wild animal, we spotted a wild reindeer
grazing across the road. After taking a bunch of photos till the Aurora died,
we headed back. This spot, with the clear sky is called a „Blue Hole‟. It was
surrounded by heavy snowfall.
We got back to Tromso in the nick of time, after driving all night
through a horrific blizzard, high on coffee and energy drinks. My
brother caught his flight, and I went back to the hotel, and slept all day.
Contributions from the Prasad family and SPACE Educator, Rishabh
Photo courtesy: Prasad family
Watch out for our next issue to know how to best plan your
trip for an Aurora sighting!
Over the several decades, the moon landing has always been
an object of scrutiny. Some have implied that it would have
been physically and technologically impossible to land men on
the moon and return them home. So was it all a hoax, after all?
One of the questions raised by conspiracy theorists was that
why there are no stars in the photos taken on the moon?
Apparently there is considerable amount of sunlight reflecting
off the lunar surface. So, in order to take crisp pictures, the
camera is needed to be set at a small aperture setting, so it
cannot gather enough light from the stars to be seen.
Why Is the American Flag waving even in the absence of air on
the moon? Due to the design of the flag, it has rigid,
extendable support pieces on the top and bottom so that the
flag would look taut.
The flag when being installed, was unfurled and started
swinging like a pendulum due its rigid structure. This is
possible both in presence or absence of air.
Why do the shadows point in different directions? Well, the
shadows points in the same direction when they are at the
same level and in uniformly grey terrain of the moon; it is
sometimes difficult to distinguish changes in elevation.
Also, why Is there no visible flame from the rocket? Simple.
The type of fuel that was used (a mixture of hydrazine and
dinitrogen tetroxide) mixes together and ignites instantly,
producing a "flame" that is transparent.
Did men really land on the moon?
Equinox or Equilux that’s the big Q.
By CB Devgun, President, SPACE
An equinox occurs twice a year (around 20 March and 22 September), when
the tilt of the Earth's axis is inclined neither away from nor towards the sun,
the center of the sun being in the same plane as the Earth's equator. The
term equinox can also be used in a broader sense, meaning the date when
such a passage happens. The name "equinox" is derived from the Latin
aequus (equal) and nox (night), because around the equinox, night and day
are about equal length......... Well almost equal but not equal and that‟s the
We all have been told and taught about this in our geography lessons but
never dared to question the simple fact presented to us. Let‟s find out
what exactly happens on equinox day and whether its equal day and night
This year’s equinox day (20th March) will have sunrise at 06:26 IST and sunset at 18:32 IST -
so it’s not equal day and night.
The moment of the equinox is defined as the point at which the centre of the sun‟s disk crosses an
imaginary line in the sky called the celestial equator, the projection of the Earth‟s equator out into
The sun (and the Moon and all the planets) move along a line in the sky called the ecliptic, the
projection of the disk of the solar system out into space. These two lines, the equator and the
ecliptic, circle the sky, and because the Earth‟s axis is tilted at around 23.5 degrees the angle
between the equator and the ecliptic is 23.5 degrees, and the two circles meet at only two points,
called equinoctial points.
Over the course of the year the sun, as seen from Earth, appears to make one
complete circuit around the ecliptic, as the Earth in fact orbits the sun. And so on
two days each year the sun‟s path crosses the equator. This means a number of
1. that an observer at the equator will see the sun directly overhead at mid-day on
2. that the sun will rise due east and set due west on the equinoxes (on all other
days the sun will rise either north or south of east, and set north or south of west)
3. the length of day and night are nearly equal
On this last point, they are not exactly equal, for two reasons:
1. the sun appears as a disk in the sky with a radius of around 16 arc minutes, and so the top of the sun appears to rise
while the centre of the disk is still below the horizon, and the instant of the equinox is measured with respect to the
sun‟s centre, and
2. the sun‟s light is bent, or refracted, in the Earth‟s atmosphere, so that rays from the sun can light you up even before
the sun rises, and keep you lit after it sets, with the degree of refraction being around 34 arcminutes
These two factors combine to mean that the sun will appear to have “risen” when the centre of the disk is still 50
arcminutes (16 + 34) below the horizon, making the amount of daylight longer than the expected 12 hours. How much
longer depends on where on Earth you are, but in the Delhi the length of the day is approx. 12 hours 7 minutes, rather
than exactly 12 hours.
Due of this effect, the days on which the length of day and night are exactly equal, called the equilux, occur a
few days before the spring equinox and a few days after the autumn equinox. This date will vary depending on
where on the Earth you are, whereas the equinox is a fixed instant in time. In Delhi “Equilux” will happen on
16th March when sunrise and sunset would be at 06:30 and 18:30 IST!!!
This year’s Vernal Equinox slated for the 20th March at 16:57 UT or 22:27 IST
ASTRONOMY AT HOME
The purpose of this activity is to understand how the shadow moves with respect to the
movement of light and also to understand the relationship between the angle of light source and
the shadow's length. After conducting the activity we shall be able to understand how shadows
form, how they behave based on different type of light sources and their correlation.
What You'll Need
1 – tube of glue
1 – Square card Board of any size larger than 6” in size.
1 – Square cardboard of 2”X2”
1 – Gnomon
1 – flashlight
What to Do
Cut a small square piece out of the cardboard an inch each side. Next, push a toothpick
into the centre of the small cardboard piece. Put this piece on top of a larger piece of
cardboard at one end.
Shine your flashlight on the gnomon to create a shadow line. Try different ways of making
the shadow line change its direction and its length.
1. Moving the Flashlight: Without moving the gnomon, make the direction of the
shadow line change by moving the flashlight.
E X P E R I M E N T
This way you will observe the shadow moving in the direction opposite to the direction in
which you are moving the torch. This is possible only when the source of light is close to the
shadow casting object
2. Moving the Toothpick: Without moving the flashlight, but keeping it pointed at the
gnomon, move the gnomon around and observe what happens to the shadow.
3. Using the Sun as the Light Source: You can also form a shadow line by placing a gnomon
under direct sunlight. This can be done by going outside. What happens to the shadow when you move
the gnomon around in the sunlight? How is it similar or different to the shadow created by the flashlight?
What's going on?
As we move the source of light or board we will see the shadow moving in the opposite direction which
tells us that shadow always falls in the opposite direction. The shadow will be longer and fainter as the
source of light is far whereas it will be short and dark as the source is close to the gnomon.
You should notice some interesting differences between shadows created by the flashlight and those
created by the Sun. Because the Sun is so far away, you may have noticed that the angle of the
shadow pointed in the same direction when you moved the gnomon whereas in case of the flashlight,
the shadow moves in different angles, always opposite to the flashlight. Since the light source of the
flashlight was much closer, the shadow behaved differently.
Also one more thing we can observe is the length of shadow gets shorter when the source of light goes
higher, almost vertical whereas it grows longer as the flashlight comes close to the board with light
falling parallel to the board.
When you observe the shadow using the sunlight, the shadow will moves in the same direction which
shows that the shadow will not change if the source of light is very far away.
Fill your observations in the Log Sheet. The log sheet will give you a quantitative
analysis of the shadow movement with respect of the movement of source of light. One
can learn and understand the motion of shadow with respect to the motion of light
Log sheet for Shadow Measurement
Serial Number Direction of Shadow
Movement (Same or
Length of Shadow
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