Transcript What is an Eclipse

How to See the Eclipse in Singapore
9 March 2016
Koh Joo Beng
B. Eng (Elect), MBA, MSc (Astronomy), FIPS
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Overview
Part I
• When is the Eclipse
• What can I see
• How do I see it
• What else can I do
during an eclipse
• What if it’s cloudy
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Part II
• What is an Eclipse
• What are the types
of Eclipses
• Geometries of
Eclipses
• Phases of an Eclipse
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Part I
For the Impatient…
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“Wow” or “Meh”?
Are Solar Eclipses rare for Singapore?
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1965
1969
1974
1980
1983
1988 x 2
1993
1995
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1998
1999
2003
2004
2006
2009 x 2
2010
2012
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2013
2016
2019
2020
2023
2027
2028
Annular!
You should be able to see several in your lifetime, but there
are only a few significant ones. Do NOT miss the 2019 eclipse!
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When is the Eclipse?
• Singapore
– Next Wednesday
– 9 March 2016, 7.23am to
9.32am
– Maximum eclipse – at
8.23am
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What can I see?
• Partial Eclipse – Chomp
Chomp?
• Sun will still be very bright
– but it will be 89% covered
– and will feel only 1/7th of
the heat (and light)!
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How do I see the Eclipse?
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Need Solar Viewers
Or welder’s glass #14 only
Telescope with Solar Filter in front of lens
Binoculars with Solar Filters in front of lenses
If Cloudy, can look directly, but don’t override natural
instinct to look away.
With Hydrogen-alpha telescopes
#14 Welder’s glass
How should I NOT see the Eclipse
• Don’t stare at the Sun. Don’t override natural instinct
• Darkened film negative
• Any other Welder’s glass
• Reflection in Bucket of water
• Telescope or Binos without filters or with filters
behind lenses
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Where to Look
• The Sun will rise at 7.12am.
• Look to the East horizon towards the Sun
• Details:
– Max Eclipse at 95° from North and 17.1° from
horizon
– Direction: 94 ° to 96°
– Altitude 2.1° to 34.2°
• Check out direction the morning before.
• Avoid trees or buildings on Eastern horizon.
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What Else is there to Do?
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Pin hole projection
Pin hole art
Look at shadows of tree leaves
Feel the difference
Take photo with smartphone
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What if it’s cloudy?
• If it’s partially cloudy, keep
checking for holes in the
clouds
• Still go outside and see if you
can “feel” the difference
• Watch the live feed of the
total solar eclipse courtesy of
Panasonic at
http://news.panasonic.com/g
lobal/eclipselive2016.html
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End of Part I
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Part II
For Scientific minds
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What is an Eclipse
Wiki : An obscuring of the light from one celestial body by the
passage of another between it and the observer or between it and
its source of illumination.
My Simple Version : Casting of a celestial shadow onto an object
or an observer.
Solar
Eclipse
Lunar
Eclipse
Not to Scale!
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Types of Solar Eclipses
• Total or Annular? Is due to the
elliptical orbit of the Moon
(and also the Earth)
– Moon at apogee (furthest) =
Annular Eclipse.
– At perigee (closest) = Total
Eclipse
Not to Scale!
Total
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Annular
Partial
1 Mar 2016
Why not 13 eclipses a year?
• On Youtube at http://youtu.be/E1B3RLf1A1s
• Or search Youtube for “Solar Eclipse Educational
Video”
• Or click here.
• Interactive app
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Phases of a Total Eclipse
• 4 “Contacts” depending on which “limb” or edge
of Moon-Sun is in contact.
1st Contact
2nd Contact
3rd Contact
4th Contact
• Partial eclipse only has 1st and 4th contacts
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Total Eclipse - Extremely rare visual treats!
• Possible to see only during Totality (2nd to 3rd contact)
Composi
te
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Oddities
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The Corona!
1/64 secComposite
2 sec of 8
Composite
exposures
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Some trivia…
Eclipses are AWESOME for physicists and astronomers!
– Is it just LUCK that the Sun and Moon are the “same” size in the sky?
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Sun is 400 times larger than the Moon
Sun is 400 times farther than the Moon
Both subtend almost exactly the same angular size of 0.5 degrees!
– No other planet in Solar System has total eclipses
– Total Eclipses on Earth are “current”
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Earth is 4.5 billion years old
Moon is receeding 4cm/yr.
100 million years ago, no annular eclipses
100 million years later, no more total eclipses!
Eclipses are AWESOME for travelers and photography enthusiasts!
– On average, staying in same place – chance of seeing a total eclipse is 1 in 400 years!
– Photographic opportunity during totality is in order of 1-4 minutes. Very challenging!
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In Conclusion…
Don’t miss the Opportunity to see the eclipse next
Wednesday
Keep Fingers (and toes) crossed that skies in the East
will be clear and cloudless!!
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Questions?
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Thank you!!
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The End
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BACKUP MATERIAL
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DO YOU WANT TO KNOW MORE ABOUT ASTRONOMY?
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Basics of Astronomy
 Astronomical vocabulary, distance units, parsec, light year
 The motion of the planets, elliptical orbits, Keppler’s laws.
 Seasons, and why they occur, Earth’s tilt.
 The Lunar Cycle
 Eclipses, how they occur, differences between Lunar and
Solar eclipses
 Local coordinates, Celestial coordinates, Galactic
coordinates,
 Newton ’s Laws
 Nature of light
History of Astronomy
 The Scientific Method
 Ancient astronomers, Galileo, Copernicus, Tycho Brahe
 Archaeastronomy
Intermediate Astronomy
 Colour of Stars, Relationship of Colour to temperature
 Spectral lines and chemical composition
 The Inverse square law of brightness, H-R Diagram
 The Doppler effect
 Multi-wavelength astronomy, Radio, X-ray, Infrared,
Gamma-ray.
 Black Holes, Quasars and Active Galaxies, Neutron stars,
Pulsars, White Dwarfs
 Galaxies, The Milky Way


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Astronomy Equipment
 Refractors, Reflectors, Cassegrains and other telescope
designs
 Telescope mounting systems, Alt-Az vs Equatorial.
 Astrophotography, Polar alignment, Focusing in the dark,
CCD, Image processing
 Telescopes in Space, Hubble, Chandra.
 Large telescopes of the World, Keck, VLSI, VLT, ELT,
Solar system overview and Birth Theory.
 Earth
 The Moon
 The Sun as a star.
 Mercury, Venus, Mars
 Jupiter, Saturn, Uranus, Neptune
 Pluto, discussion of Pluto being a minor planet.
 Comets and asteroids, Meteorites.
Cosmology
 The Big Bang, Big Crunch
 Einstein’s Theory of Relativity, Special, General
 Relativistic Doppler Shift
 Cosmological Constant
 Hubble’s Law
 Expansion of the Universe
 Cosmic Microwave Background
 COBE, WMAP
And much much more....
To purchase your own telescope
or other astronomy-related equipment,
visit www.astrobargains.com
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1 Mar 2016
OTHER USEFUL LINKS
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Stellarium - Planetarium program www.stellarium.org
Celestia – Space Simulation www.shatters.net/celestia
Singastro – Singapore’s astronomy forum www.singastro.org
Singastro Wiki - Wiki for Astronomy Beginners in Singapore
www.singastro.org/web/mediawiki
Astronomy.sg – Singapore astronomy portal www.astronomy.sg
Printable Sky Charts – Cartes du Ciel www.stargazing.net/astropc
Interactive Sky Charts
 From Sky & Telescope :
http://www.skyandtelescope.com/observing/skychart/
 Astronomy Magazine : http://www.astronomy.com/asy/stardome
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