"Science of Lunar Eclipse through FAQ & Celestial Beauty of Saturday"

A Week prior to the 10th Dec 2011 Total Lunar Eclipse, AKG is beginning the Lunar Week from Sat ( 03rd Dec) to 10th Dec 2011. 

The Lunar Week's inaugural article is here.I am proud to present this article titled as "Science of Lunar Eclipse through FAQ & Celestial Beauty of Saturday" 

The article focuses on explaining the science of Lunar Eclipse through Frequently Asked Questions I have encountered with written in a simple language to enable the readers to understand it. Also given below are the datas from Eclipse NASA giving insight about the event on 10th Dec 2011 when a Total Lunar Eclipse will be visible. 

The Eclipse is important for me and my hometown as the next eclipse ( Total Lunar) will be visible nearly after 6 years !!! 

So sit back and enjoy and wish you a Happy Lunar Week.

AND!!

FOR THOSE WHO WILL BE ABLE TO SEE THE ECLIPSE: MARK THE DATE --- Sat,10th Dec 2011

Akshay Deoras

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"Science of Lunar Eclipse through FAQ & Celestial Beauty of Saturday"

By Akshay Deoras

The coming Saturday,10th Dec  is going to be a wonderful evening for all the astro lovers! There will be a Total Lunar Eclipse on the evening of Saturday which will be the second one of the year ( After 15th June 2011) when the first total lunar eclipse was seen. 

However, the weather didn't allow any view of the eclipse from Nagpur. 

The Eclipse is going to be visible completely  in East Asia,Australia,New Zealand.In India the moon will rise before the beginning of penumbral eclipse in North East states,East central region,Eastern Jammu and Kashmir. For central India including Nagpur,and the remaining regions the moon will rise in the penumbral eclipse. Penumbral Eclipse happens when the moon enters the penumbra or outer faint shadow of the Earth. As a result the TOTALITY PHASE will be seen by these areas. 

However for much of Africa,Europe the eclipse last stages will be seen and so it will just be restricted to Partial Lunar Eclipse for them. The Eclipse will not be visible in extreme west africa,South America and Antarctica prominently. 

The Details for India

I must say that cities in the entire Seven sister states,West Bengal,Sikkim,Bihar,Jharkhand and some parts of Chattisgarh,Extreme eastern J&K  will have the moon rise before the P1 stage. So they can experience the entire phenomena. 

For Kolkata moon will rise on 10th Dec around 1637hrs (1107UT).

The general timings are - 

P1 = 11:33:32 UT ….. (0503PM IST)…..  Moon enters the penumbra 

U1 = 12:45:42 UT …. (0615PM IST)…..  Moon enters the umbra 

U2 = 14:06:16 UT ….. (0736PM IST) …  TOTAL ECLIPSE BEGINS

GREATEST ECLIPSE - 1432UT ( 0802PM IST)

U3 = 14:57:24 UT …. (0827PM IST) 

U4 = 16:17:58 UT….. (0948PM IST) … MOON LEAVES UMBRA

P4 = 17:30:00 UT …. (11PM IST) …     ECLIPSE ENDS 

WHAT WILL THE PEOPLE SEE (INCLUDING NAGPUR) ?

Nagpur Special*

For Nagpur, the moon rise on 10th is at 1723hrs IST (1153hrs UT)

Moon enters the Umbra - 0615PM IST 

Total Eclipse Begins - 0736PM IST

MAXIMUM - 0802PM IST

Total Eclipse Ends- 0827PM IST

Partial Eclipse ends - 0948PM IST

Penumbral Eclipse ends- 11PM IST

THE NEXT TOTAL LUNAR ECLIPSE TO BE VISIBLE FROM NAGPUR WILL BE ON 31ST JAN 2018

Apparent View of the Moon and Earth's shadow in Real time at 0802PM IST

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MOON'S APPEARANCE WILL BE SIMILAR AS SHOWN IN THE ABOVE FIGURE

At 1133UT, the moon's appearance will start fading slightly which is often not noticed by naked eyes. This happens as less dark shadow of Earth falls on the Moon. As the Moon starts progressing towards the Umbra Region, from 1406UT, the Totality will start and the Moon's surface will begin to cut off due to the earth and moon will start getting darker but there will be appearance of Red shades will increase and at 1432UT the moon will be BRICK RED. The reverse process will again follow as the moon leaves umbra completely at 1618UT. 

The Eclipse will be over at 1730UT! 

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The Myth of Eclipses

The phenomena of eclipse wasn't as enjoyable thousands of years ago as it is today especially to see the copper red moon of totality.

Chinese people had mentioned first about Solar Eclipse long way back around 2134BC. People of the ancient times used to fear from the eclipse as they thought it was a curse. Even the famous war between Lydians and Medes ended after 5 years at once as the day turned dark due to Solar Eclipse- A phenomena which they didn't understand. 

  For those who don't know the science of the eclipse, lets learn it through Frequently Asked Questions (FAQ)

Q.Ingredients for the recipe of Total Lunar Eclipse?

 A. Sun,Earth,Moon

 Lunar Eclipse occurs when the Earth's shadow falls on the moon.When I am standing in front of a tube light my shadow falls behind ( Say there is a screen). This screen is the moon and I am the earth for consideration

Q.How is the moon's orbit around the Earth?

A.The orbit of the moon around the Earth is an ellipse ( curve obtained when you join letter "u" from top with inverted "u"). Moon's orbit around the earth makes an angle of 5 Degree 14 mins with the ecliptic ( Ecliptic plane is the plane in which Earth orbit's the Sun)

Its like when you consider a clock let the minute hand pointing from 9 to 3 be ecliptic. So the second's hand pointing from 10-4 and 8-2 is the moon's orbit around the earth but in the real three dimension of space.

Thus the second's hand crosses the plane two times.At 9'o clock and 3'o clock.The same is the concept of Moon.

Moon's orbit crosses the ecliptic two times during one orbit referred as nodes( Explained below)

Thus for earth's shadow to be casted on moon or moon blocking the solar disc, the moon must be in a common plane with earth and sun i.e have co-planar orbits.

 Q. When Moon crosses the ecliptic twice a month, then why there isn't eclipse twice a month?

      A. Consider the below figure

COURTESY- DWIGHT ENNIS

The Nodal axis is a line joining the two nodes. That is for eclipse moon must be at one node which it does twice in its orbit BUT the sun ALSO must be at the  other far end of the stick ( Nodal axis). It is supposed to happen every 6 months. 

Q. Why doesn't the Eclipse re-occur at the same date after 6 months?

A.The combined gravitational pull between Earth-Moon-Sun creates a wobble in that nodal axis and so it oscillates. Due to this the dates of eclipses aren't repeated at the same dates.

Q. WHY MOON APPEARS RED SHADE DURING TOTALITY?

A. When the Totality stage arrives, the moon enters much of the Darker portion ( UMBRA) of earth's shadow. Logically one says that during maximum eclipse, the moon's view must be blocked totally making it dark and invisible for sometime but it doesn't happen. 

It appears Brick or Copper Red ! 

The reason is at this  stage, the sun's light is still traveling in the earth's atmosphere. We know that the WHITE light is composed of seven colors but as per Rayleigh's Scattering, the color having less wavelength will scatter more i.e prominently Violet,Blue and others. Since the Red color has higher wavelength than other colors, its less scattered and so when the sun's light exits the earth's atmosphere the red color spectrum is dominant. This light falls on the moon and we see its reflection. If there is more dust,volcanic ash etc in atmosphere then Moon's color will appear different !  There is a scale known as Danjon Scale which determines the color of moon which will be seen during total lunar eclipse 

The French astronomer Andre-Louis Danjon proposed a useful five point scale for evaluating the visual appearance and brightness of the Moon during total lunar eclipses. 'L' values for various luminosities are defined as follows:

     L = 0     Very dark eclipse.Moon almost invisible, especially at mid-totality.    

     L = 1     Dark Eclipse, gray or brownish in coloration.                Details distinguishable only with difficulty. 

      L = 2     Deep red or rust-colored eclipse.  Very dark central shadow, while outer edge of umbra is relatively bright.  

     L = 3     Brick-red eclipse.Umbral shadow usually has a bright or yellow rim.   

     L = 4     Very bright copper-red or orange eclipse.Umbral shadow has a bluish, very bright rim.

Courtesy- Arvind Paranjpye

Q.Is Lunar Eclipse SAFE to Watch?

A. Absolutely YES!

Infact I will encourage the readers to hunt with their telescopes or binoculars or simple naked eyes to watch this celestial beauty..

Q.Is Lunar Eclipse connected to any Natural Calamity,disasters etc. 

A. Absolutely not. 

Q.What is the speed of the moon during this projection through Earth's shadow?

A. Around 1.6km/sec 

More questions are welcomed at- 

akshaydeoras@hotmail.com

SCIENCE OF ECLIPSE ( LUNAR) AND THE JUNE 15 2011 TOTAL LUNAR ECLIPSE

ABOVE-

THE SIMULATION SHOWING HOW THE TOTAL LUNAR ECLIPSE WILL APPEAR OVER NAGPUR,INDIA

TIMES DISPLAYED ARE LOCAL = GMT + 5.30HRS

ABOVE- PHASES OF MOON

ONLINE LIVE ECLIPSE ( DURING THE EVENT)

The Central Lunar Eclipse will be shown live through WEBCAST -
By Sky Watchers Association of North Bengal(SWAN) Siliguri, West Bengal
http://www.skywatchersindia.com/
or
http://www.livestream.com/swansiliguri
By Eclipse Chaser Athaenium New Delhi
http://www.ustream.tv/user/eclipsechasers
By Astronation.net at http://www.astronation.net/webcam/10022/342/mondfinsternis-juni-2011.html

The decade's first lunar eclipse as well as the first total lunar eclipse of this year & decade shall take place on Wed 15th June 2011

The Moon shall turn Coppery Red as the scattered light due to Rayleigh's effect strikes the moon and gives the glow!

Science of Eclipse-

Like known by all an Eclipse is an obscuring of light from any celestial object as another cellestial object passes in between the source and observer or the light from the source is blocked by an object leading to visible shadow of that object on another.

Lunar Eclipse is annually occurring phenomena.

Orbital Configuration of the Moon

Since Earth-Moon form a Planet-Moon system, both of them rotate about their centre of mass referred as Barycenter. This barycentre is about 4700km from Earth's centre which

is about 3/4th of Earth's Orbit ( Apx 6400km)

( Right- The Earth as centre and the moon revolving about centre of mass shown as PLUS sign)

The orbit of the moon around the Earth is elliptic. Moon's orbit around the earth makes an angle of 5 Degree 14 mins with earth's celestial equator as well as the ecliptic ( App

arent path of Sun in Earth's sky as viewed from earth or the path traced by earth as seen from the sun)

Its like when you consider a clock let the minute hand pointing from 9 to 3 be the so another minute hand pointing from 2-7 is the moon's orbit around the earth but in the real three dimension of space

Thus moon's orbit crosses the ecliptic two times during one orbit referred as nodes( Explained below)

Moon completes a revolution around the Earth in 27.231 days

( IMG COURTESY- ARVIND PARANJPYE)

Nodes of moon's orbit around the Earth-

Nodes are the two positions in the orbit of moon around the earth where the moon's

orbit intersects the ecliptic. Thus for earth's shadow to be casted on moon or moon blocking the solar disc, the moon must be at a common plane or have co-planar orbits.

But it is not necessary that every approximate 15 days when the moon reaches the node ( Descending Node- When the moon is declining from the ecliptic axis MOVING NORTH TO

SOUTH and

Ascending node- When the moon is inclining the ecliptic axis MOVING SOUTH TO NORTH) eclipse will take place as its not necessary that the relative angular separation of sun and moon is 180 Deg ( Case of Lunar Eclipse) when the moon passes from non sun facing side of the earth or 0 Degree ( Case of Solar Eclipse) when moon is in between earth and sun

For any eclipse, Solar or Lunar- New Moon or Full Moon is required respectively. ( Node and Ecliptic)

Why is this??

When there is New Moon, the moon is in between earth and sun ( Not necessary that its always in a liner path) but remains in inclined or declined position depending on its motion.

During full moon, the moon is in opposite direction that is at the non sun facing side of the earth.

Thus as per definitions of solar and lunar eclipse relating to position of Moon with respect to earth the above condition is satisfied.

During every orbit, moon has the same cellestial longitude required for eclipse ( In 29.53 days) but the celestial latitude is not proper and the concept of Ecliptic limit is introduced

Ecliptic Limit-

It is that minimum angle between the position of moon and the node of the moon's orbit required for an eclipse to occur

Its of two type-

Major Ecliptic Limit

A Lunar Eclipse MAY occur when the moon is at

11° 38' ( Celestial Latitude) of a Node, and a Solar Eclipse MAY occur if there is a New Moon within 17° 25' of a Node.

For a Solar Eclipse to occur, the Moon's Celestial Latitude cannot exceed 1° 27', and must be less than 58' for the Solar Eclipse to be Total or Annular.

• Major Ecliptic Orbit A Lunar Eclipse MUST occur if there is a Full Moon within 9° 39' (Celestial Longitude), of a Node, and a Solar Eclipse MUST occur if there is a New Moon within 15° 23' of a Node.

• If a New or Full Moon occurs within 5° of a Node, the Eclipse will be Total or Annular.

Additionally:

• For a Lunar Eclipse to occur, the Moon's Celestial Latitude at Full Moon cannot exceed about 55', and for that Lunar Eclipse to be Total, Celestial Latitude cannot exceed 26'

*** Also

THE MOST IMPORTANT OF ALL - FOR ECLIPSE A PERFECT LINEAR ALIGNMENT,THE SUN-MOON-EARTH NEEDS TO BE PERFECTLY ALIGNED AND THIS CAN HAPPEN ONLY WHEN THE MOON IS AT ONE OF THE NODES AND THE SUN ALSO AT ONE OF THE NODES OR WITHIN THE ECLIPTIC LIMIT

***

An Interesting animation here

Thus for any eclipse to happen,above condition mentioned be satisfied.

June 15 2011 Total Lunar Eclipse-

The June 15 2011 Lunar Eclipse shall be the first lunar eclipse of the year and THE FIRST ECLIPSE SINCE 2000 WHERE THE MOON WILL PASS THROUGH THE CENTRAL PORTION OF EARTH'S SHADOW ( UMBRA)

THE PREVIOUS LUNAR ECLIPSES ( NOT OF THE 2000 LUNAR ECLIPSE),MOON PASSED NOT THROUGH EXACT CENTRAL UMBRA BUT SLIGHTLY ABOVE CENTRAL UMBRAL REGION.

THE ECLIPSE BEGINS WITH THE FIRST CONTACT ( P1)

AT 17:23:05 UT ON WED,15TH JUNE 2011

Visibility-

Europe, Africa, Asia, Australia, New Zealand, southern South America and eastern South America. Places that won’t see the eclipse at all include Hawaii, North America, northwestern South America, Greenland, Iceland and the Arctic.

WITH THE SUN SETTING OVER EUROPE, THE CONTINENT SHALL WITNESS THE ECLIPSE AFTER SUN SETS TILL AROUND MID NIGHT.

EUROPE SHALL SEE A UMBRAL ECLIPSE MISSING THE INITIAL STAGES OF ECLIPSE AS THE MOON WILL BE BELOW THE HORIZON. THUS THE MOON WILL RISE IN ECLIPSE ONLY IN EUROPE

*** TOTALITY SHALL NOT BE SEEN BY NORTHERN SCOTLAND,SCANDINAVIA***

EAST ASIA,EAST AUSTRALIA AND NEW ZEALAND WILL MISS LAST PHASES OF ECLIPSE AS THE MOON SETS IN ECLIPSE ONLY

TIMINGS- ( UTC)

P1 - 17:23:05

U1- 18:22:37

U2- 19:22:11

GREATEST- 20:12:37

U3 - 21:03:22

U4 - 22:02:35

P4 - 23:02:15

TIMING IN INDIAN STANDARD TIME ( IST= GMT+5.30HRS)

2011	stage	Phase	time (IST)
Jun 15	1	Moon enters penumbra	22:52:52
Jun 15	2	Moon enters umbra	23:52:24
Jun 16	3	Start of totality	00:51:57
Jun 16	4	Maximum eclipse	01:42:24
Jun 16	5	End of totality	02:32:50
Jun 16	6	Moon leaves umbra	03:32:22
Jun 16	7	Moon leaves penumbra	04:32:02

CHARACTERISTICS-

*** DARKEST ECLIPSE SINCE JULY 16 2000 LUNAR ECLIPSE AS THIS TIME MOON'S CENTRE PASSES THROUGH 5.3 ARCMINUTES OF SHADOW AXIS***

*** NEXT DARKER ECLIPSE ON JULY 27 2018***

*** EARTH'S SHADOW FALLS IN CONSTELLATION OPHIUCHUS NORTH OF SCORPIUS***

B9.5Ve spectral class star BSC 51 OPH TO LIE IN THE UMBRA OF THE EARTH'S SHADOW

RIGHT-

THE MOON AS THE CENTRAL COPPERY RED OBJECT SURROUNDED BY EARTH'S SHADOW AND BSC 51 OPH TO ITS LOWER RIGHT AS TO BE SEEN FROM NAGPUR,INDIA DURING PEAK ECLIPSE

SAROS- 130

GAMMA- 0.090

PENUMBRA ( MAGNITUDE) - 2.712

UMBRA ( MAGNITUDE) 1.705

TOTALITY- 100 MINS AND 52 SECONDS

FOR INDIA-

ECLIPSE DURATION - 22:52 ( 15TH JUNE) TO 0432 ( 16TH JUNE) IST

MAXIMUM ECLIPSE AT 0142( 16TH JUNE) IST

REFERENCES AND COURTESY-

1] ARVIND PARANJPYE FOR TABULAR FORM AND IMAGE

http://www.iucaa.ernet.in/~scipop/Eclipses/Luna15jun11/lunar_eclipse_1106.htm

2] WIKIPEDIA

3] ECLIPSE @ NASA

4] CARTES DU CIEL SOFTWARE