Sky tonight for this month

Friday, August 22, 2014


For the 11 year in a row, a message about the Red Planet is popping up in email boxes, whtsapp and other social media groups around the world. It instructs readers to go outside after dark on August 27th and behold the sky. "Mars will look as large as the full moon," it says. "No one alive today will ever see this again."

Don't believe it!!!!!

Here's what will really happen if you go outside after dark on August 27th. Nothing. Mars won't be there. On that date, the red planet will be nearly 318 million km away from Earth and completely absent from the late night sky. This mail is a hoax but it has done some service to Astronomy by making it popular among masses so that they can at least have a discussion on the matter. We will just go through the mail again and see why it is a hoax. The original mail is in bold and italics followed by explanation

1. Since this won't happen again between 5,000 and 60,000 years...might be worth a look now: Mars - The Red Planet is about to be spectacular!

Mars always looks spectacular as a small red dot in the black skies!!

2. This month the Earth is catching up with Mars in an encounter that will culminate in the closest approach between the two planets in recorded history. The next time Mars may come this close is in the year 2287. Due to the way Jupiter's gravity tugs on Mars and perturbs its orbit, astronomers can only be certain that Mars has not come this close to Earth in the last 5,000 years, but it may be as long as  60,000 years before it happens again.

Mars comes close to earth once in 2 years (26 months to be precise) and that’s called opposition. Last time it happened was in April 2014 and will happen next time in May 22, 2016. Also when planet is closest, then Mars rises as sun sets but in this case mars is setting within 3 hours of sunset.
This month on 27th August it will be at a distance of 1.35 AU from the earth (Approx. 201 million kms from earth). Jupiter’s gravity tug has got nothing to with the phenomenon. It came closest to earth in last 60000 years on 27th August 2003 and that’s the only resemblance with the date.

For your information last 4 oppositions and the next one is given below:

2007     Dec 24                  0.5929 AU          88.7 million kms
2010     Jan 29                   0.6639 AU          99.33 million kms
2012     Mar 03                 0.6743 AU          100.93 million kms
2014     Apr 08                  0.6175 AU          92.3 Million kms
2016     May 22                 0.5032 AU          75.2 Million kms

3. The encounter will culminate on August 27, 2014 when Mars comes to within 34,649,589 miles of Earth and will be (next to the moon) the brightest object in the night sky. It will attain a magnitude of -2.9 and will appear 25.11 arc seconds wide. At a modest 75-power magnification…

When it says it will be brightest object next to moon and with a magnitude of -2.9 and will appear 25.11 seconds of arc, the statement has no meaning. But the catch in this statement is that through a 75x magnification from the telescope it will look as if you are watching the moon with naked eye. For you information, full moon has a magnitude of -13 which as compared to -2.9 is huge (around 10000 times difference in brightness). Moon as seen with naked eye looks as a circle of 1800 seconds of arc (half a degree) in comparison to Mars as mere 7 arc sec. Mars on 27th August, 2014 will be shining meekly at magnitude 0.5 which is almost quite fainter than what is written about mars on that day (its like watching at 100 w bulb at a distance of 39 kms) and it will 201 million kilometers away from earth. In fact Venus will be the brightest object in the skies this august but in the early morning skies.

4. Mars will look as large as the full moon to the naked eye. Mars will be easy to spot. At the beginning of August it will rise in the east at 10 p.m. and reach its azimuth at about 3 a.m.

Totally false statement. As per previous Paragraph, Mars can never look as large as full moon to naked eye. Mars will set by 10:30 pm on that day.

5. By the end of August when the two planets are closest, Mars will rise at nightfall and reach its highest point in the sky at 12:30a.m. That's pretty convenient to see something that no human being has seen in recorded history. So, mark your calendar at the beginning of August to see Mars grow progressively brighter and brighter throughout the month.

Totally false statement: Moon is not a planet first of all. And in august around 27th  mars will rise at around 11:48 am IST, will be achieving its highest point at 3:00 pm IST and will set by 10:30 hrs IST and Moon will be in its waxing phase just after new moon on 27th August and will rise set by 19:30 IST. Full Moon occurred on Aug 10th, on the day of rakhi festival.  The mail/message which you have received is a copy of the mail meant for 2003 closest approach. These two heavenly bodies will never be in the same sky at any given time.

6. Share this with your children and grandchildren. NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN

Yes, share the news with your children and grandchildren because it will invoke their interest in Astronomy!!!! Do see the Mars in the evening skies these days with help of a telescope.

Written by C B Devgun, President, SPACE Foundation.

Friday, July 11, 2014

SuperMoon of 2014

Have you ever wondered about or even tried to look at the size of the Full moons in different times throughout the year? You may ask why? Moon goes around the earth in an elliptical orbit so it is not at the same distance from us all the time (as its not a circle), as a result it appears to grow and shrink (not too much) as seen in the skies (though it does not grow or shrink physically!!).

And its more apparent on the day of the full moon when we see the whole disk illuminated. Now just imagine seeing a bigger full moon - it means that moon is at perigee (point nearest to earth) or near perigee at that time. As its a bigger moon then there has to be a name to it as we humans are very much inclined towards giving names to each and every thing!! They call it SuperMoon!! And this word was coined recently in late 70’s(if we talk about time scales in astronomy).

And its interesting to know that SuperMoon is a word which was not coined by astronomers but by an astrologer , Richard Nolle, who is credited with coining the term supermoon. He arbitrarily defines this as
. . . a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth. But for us its the Perigee full/new moon happening at the exact time of perigee so there is no ambiguity about the definition. Now our new definition becomes - . . . a new or full moon which occurs with the moon at its closest approach (perigee) to Earth. The technical name is the perigee-syzygy of the Earth-Moon-Sun system. We astronomers do not use the term “Super Moon” but to take it among the masses its a catchy word! As we have Supermoon, there has to be Micromoon which happens at Full moon at the time of Apogee. And if you happen to click both the moons with same setup, you would find a drastic change in diameter which is around 14% and thats quite large!!

Now lets see how many Full Moons fit into this definition. We have not taken New Moon in this category as it can't be seen at all!!! But a supermoon at new moon at the time of the eclipse play a different game, that i leave to you people to ponder. 
In present century we have the following SuperMoons which fit in the definition of Full Moon and Perigee moon happening exactly at same time (Perigee happening at F +/- 0 h):

2011 356577 km    3/19/2011    
2012 356953 km     5/6/2012   
2013 356989 km     6/13/2013   
2014 356896 km      8/10/2014   
2034 356447 km     11/27/2034   
2054 356511 km     1/24/2054   
2073 356720 km    5/23/2073   
2094 356867 km      8/26/2094   
2095 356685 km      10/13/2095   
There are quite a lot of more so called supermoons if we relax our stringent rules to allow for few hours +/- difference between Full Moon and Perigee Moon

We come back to our discussion about supermoon again. You can see that there is one supermoon coming on 10th August 2014. So what big deal about it? Well On that day the Full Moon will be approximately 14% bigger than the Full Moon on Apogee and will be 30% more brighter than it. If you plan to click the image on that day then make sure that you click with same setup another image on March 5th next year when we have the Full Moon happening near to Apogee and then you can actually calculate the difference we have talked about. Above Image is an example which we did in 2011. And interseting when you see the above image and the once you will take, you will see the phenomenon which we call as liberation of the Moon, well that's another story to tell!!!! But Do enjoy the illuminated Moonlight dinner on that night with your near and dear ones!!

Monday, July 7, 2014

Sun as seen at two vantage points in the earth's orbit

We all have learnt that earth while going around the sun in an elliptical orbit comes closer and goes farther away from the sun and in an year during its orbit, we have two days perihelion (earth being closest to Sun) and Aphelion (Earth being farthest away from the sun).

So that in layman's term means we should see Sun slightly bigger on the day of Perihelion day and slightly smaller on the Aphelion day (as compared to average distance what we call as the 1 Astronomical Unit). To put that to visual understanding, I clicked one image of the sun near Aphelion day on 6th July (though 4th July was Aphelion day but clouds did not permit me to click the sun, anyways in 2 days earth hasn't moved much as far as astronomical distances are concerned) and my next target is to click it on Perihelion day on around 3-4 January and then compare the size of the sun's image. While searching through my archives, I found that I clicked few pics of sun during December last year with same set of equipment. That was on 1 December, 2013. So I tried comparing these two images just to get a visual idea as how much the difference is there. You can have a look at the combined image and see how big and small sun looks while being at perihelion and aphelion. It is quite a visual treat to see the difference, and also a nice tool to teach our educators and students as how and why we have longer total solar eclipses in July and not in January!! Well that's another point to ponder about!!
For those who are technically aligned, here are the numbers to play with during the days i took the image
Canon 500D, 250 mm FL

On 6th July, 2014:

earth distance from Sun: 1.017 au or  152.1 million kms
Apparent Size of Sun:  31 arc min  26 sec

On 1 December, 2013
Earth distance from sun: 0.9859 au or 147.5 million kms
Apparent Size of sun:  32 arc min  25 sec
So we have almost 1 arc min difference in apparent dia of Sun
Have a look at the image and enjoy!!

Written by CB Devgun, President, SPACE Foundation

Wednesday, July 2, 2014

Earth farthest from sun

Earth farthest from sun

4th July, 2014 – Aphelion day

We all know that earth goes round and round around the sun. Well it almost does that but there a small twist to the statement. It ALMOST goes in a circle. Thanks to Kepler, who gave us insight into how these wanderers go around the sun, all planets in our solar system travel around the Sun in elliptical orbits. It's Kepler's 1st Law. Some planets go around sun in more elliptical orbit than others. Most planets follow orbits that are more elliptical than Earth's orbit. So in a sense earth’s orbit is closest to being a circle in the whole solar family. Even then the slight deviation from a circle gives us two positions of earth when it’s farthest and closest to sun.

The orbits of Mercury (red), Earth (blue) and Mars (black). The solid lines indicate each planet's elliptical path around the Sun. The dotted lines show circular paths with the same mean separation from the center. Earth is almost exactly the same distance from the Sun at aphelion and perihelion, but the orbits of Mars and Mercury depart significantly from a circle.

On July 4th, 2014 at 15 hrs UT or at 20:30 IST, the Earth is at its farthest point from the Sun (aphelion), the distance at that time is 152,097,040 km, which is about 5 million km further away than its closest point in early January. It does appear strange that in July we have earth farthest away from sun. Isn’t it? And to top it all total energy received from sun by the globe on aphelion is around 7% less than what we receive when it is closest to the sun (perihelion).

Now you may ask if sun is farthest then why is the temperature not going down?  There are many reasons to it. Blame it on the tilt of earth’s axis. Actually, our seasons are determined by the tilt of the Earth and not by how close the Earth is to the Sun. Well that’s another story to tell.

Sunlight raises the temperature of continents more than it does oceans. (Land has a lower heat capacity than water) In July (aphelion) the land-crowded northern half of our planet is tilted toward the Sun. Aphelion sunlight is around 7% less than sunlight at perihelion, but it nevertheless does a good job warming the continents. In fact, say climate scientists, northern summer in July when the Sun is more distant than usual is a bit warmer than its southern counterpart in January.

So enjoy the warm or rather scorching sun (or cloudy day!) on 4th July as a celebration to the Aphelion day.

Friday, June 13, 2014

Full moon on Friday " the 13th" !!!!

Don't miss out !!!
Full moon on Friday " the 13th" !!!!

Friday the 13th is a superstition in western world for no reasons but still the date and the day invoke a sense of fear but here we astronomers are not bogged down by these days and dates but sometimes some interesting coincidence make these days and dates quite memorable, Today 13th June, friday happens to fit in the friday the 13th superstition but on top of that we have a full moon on this day and as the western world has a name for every full moon (though how irrational is the way they name it) and as the June moon does not rise quite high in the skies it is termed as Honey Moon (not to be confused with those nuptial knots kind!!) Lets see how much fun we can get from numbers here. Moon get full today at 4:14 UT (9:44 IST) and lets see when was the last time we had full moon on Friday the 13th and that too in june. Well the date comes to be Friday Jun 13th 1919. Interesting, isnt it? Now lets see when will it be again full moon on Friday the 13th in june? It would be in 2098!!! So lets just enjoy the number game and make astronomy more Fun by sharing these things with your friends and near ones!!! Just make sure that you tell them that Friday the 13th is just a normal day while Erath keeps on going across the sun for Billions of rounds!!!