Blue Moon and how we see it

On 31 March we are witnessing Blue Moon. You might have encounter with term Blue Moon in news media. In media, news usually appear with Blue color moon picture and says 'this month we are going to see blue moon'. Many people wonders  how moon will be in blue color? it must be a great sight in sky seeing blue color moon. But, Blue moon is nothing to do with color. It is a name of moon which occurs as a extra full moon in a month or in a astronomical season.

Blue moon is not actualy blue in color

In every cultures moon has different names. In India too have different names according to seasons and festivals. In western culture, they also given name to full moon according to seasons. Like, October month moon is called as Hunters Moon because peoples who lives at northern hemisphere start collecting food and meat for coming winter. December moon is called as cold moon and March moon is called as worm moon. These names are not uniformly used in entire western culture. These also change from tribe to tribe or culture to culture. 

Every culture or tribe made their own calender based on sun or moon to maintain their yearly activities. Every season like spring, summer, fall and winter usually see three full moons. These seasons happens due to sun motion in Earth's sky. Sun takes 365.24 days to complete one cycle in Earth's sky which we called a year. (Earth move around the sun in space and from earth we see sun is moving in sky. Its a relative motion we observe.). But, to complete one cycle in sky moon takes 29.5 days. When sun colpletes its one cycle in 365.24 days, by the time moon complets 12.37 cycles. So, each calender year get around 11 extra days from moon cycle. Due to accumulation of these days from lunar cycle we see extra full moon in a season after two or two and half calendar year. This extra full moon is called as Blue moon. Indian calender make adjustment in calendar to stay with seasons by inserting Adhik Maas after two and half year. (Incorporating extra moon cycle vary with different calendars.)

Another way to describe Blue moon is, a second full moon in same calendar month. This calendar year 2018 has two Blue moon month one was January and second is March. This is rare, next calendar year with two Blue moon will be 2037. But, sinlge Blue moon month happenes every two and half year. Next, Blue moon will appear in Octber 2020. 

Astronomical events and news media

When people hear or read about blue moon, they usually think that moon will appear in blue color. Because, the way news media present this event. In age of Information and technology news media has become most unscientific mode of information. Many times not enough research happens aroud topic and to just grab attention of public, news are presented in dramatic way which leads to misconception. News Media also wrongly present other natural or astronomical events like eclipses, appearance of comets or when mars comes near to earth in its orbit. For example, news about eclipse will show less about science behind it and more about effect of eclipse on someones zodiac signs and how it will doom person's fate. This leads people and society towards superstions. I think every time nature gives us opportunity to become more rational and logical, we misuse it and becomes more irrational. News media has played very important role for social awareness time to time. Now, in this time it is very much required a role of scientific and rational media to create scientific attitude in society. 

Why we cant see Stars in day time?

Night sky with full of shining stars is always spectacular site to view from the country side. If moon is not present in the night then the site becomes fascinating. We cant see this view during day time. After sun set also we cant see stars suddenly appear in sky. It takes sometime for coming them out entirely until the sky becomes dark after sunlight totally goes off. Question that why we cant see stars in day time wonders most us. Whats the reason behind it?

Straight answer we get for this is due to sun's strong light we simply cant see them. But, what exactly happens when sun comes in our sky and how it limits us from seeing stars. Our Earth's atmosphere plays key part in this phenomenon. When sun comes in our sky sun's light is scattered by the atmospheric gases and dust particles. Due to this scattering earth's sky illuminates. Due to this illumination day time sky outshine other stars.

Night time sky with full of stars

We have seen that on Full moon night we do not observe much stars due to moon light. Sky near the moon is much brighter than rest of sky so in this area we see very very few stars. Same during dawn and dusk also we can see very few stars. We can understand this phenomenon by recalling our experiences, what happens if we lit small bulb in front of much brighter street lamp? in this case we could hardly see light coming from small bulb. This can be observe during night driving, if a small bike is riding ahead truck we could hardly notice bike in front of trucks brighter light. For our eyes it is difficult to sense small intensity of light in front of big intensity light source. 

Then how much brighter object we can see in our day time sky?

Many times astronomers looks distance space objects like galaxies which having magnitude more than 14. In such conditions astronomers looks for the very dark sky means having magnitude more than this object. As atmosphere scatters light due to dust and gas particle it behave as light or illuminated object. If sky appear more brighter then such faint object will disappear. Object visibility in the sky depend on how much object is bright and how much sky is bright or dark. Sky conditions varies during dawn or dusk, presence of sun  or moon in sky and nowadays light pollution from greater cities affects sky views.

Brightness of celestial objects measures in magnitude. There are two types of magnitudes astronomers use, apparent and absolute. Here we will discuss only about apparent magnitude scale. If we look at the night sky, we can see stars with different brightness. Some stars are much brighter on the other hand some are so faint that we hardly notice them. Astronomers in ancient time made a comparative scale to measure intensities of stars. They took one star for a reference which they denoted as 1 magnitude star and with the caparison to this they measure fainter stars and brighter stars. If star appear 2.5 times fainter then it will be 2 magnitude star. If it is 2.5 x 2.5 times fainter then it will be 3rd magnitude star. so, 3rd magnitude star will be 6.25 fainter than 1 magnitude star. Human eyes could observe 6 magnitude star which is 100 times fainter than 1 magnitude star. same way for brighter object if object is 2.5 brighter than 1 magnitude then it will be 0 magnitude. Brightest star of night sky is Sirius which is having magnitude of -1.45 means it is much brighter than fainter stars visible to human eyes. this measurement scale is very ancient. This method is adapted and developed by various astronomers time to time in historical time course.  If we take full moon it have magnitude of -12 and sun is having magnitude of -29 means it is trillion times brighter than any star.

Venus can be observe in day time if know its exact location in sky

Seeing objects in day time depends on many conditions like brightness of object, sky conditions and position of object from sun. Near sun, sky is much brighter so its very difficult to see anything near it although we know exact position of object. if moon is in big enough in size then its easy to spot it in day time. Venus is the second object which can be observe in day time when you know its exact position. Venus shows magnitude of -4.4 means magnitude of day time sky at that region must be below this magnitude. It also depends on position of object from the sun in sky. Sky at different distance have different brightness. It will be maximum near to the sun and as moving away from sun its brightness decrease. Many astronomers do these activity of finding stars or planet in day time sky. Its interesting and test many skills of astronomers. On various website one can get information about this. Human eyes are very poor in spotting celestial objects in day time. For spotting object you also need fine instrument like telescope and position data too. Try out how many celestial objects you can see in day time.

Note: Images used in this article are taken from various internet sources. for information I have referred astronomy books like The Sky by David Levy and Bad Astronomy by Philip Plait and many other internet sources

Total Lunar Eclipse of 31 January 2018

Hi, everyone this is long time I have written anything on my blog. I have been doing my astronomy activities but did not shared them on this blog. Today i am going to share our some experiences and photographs of total Lunar eclipse of 31st January 2018. The special thing about this lunar eclipse was it was on Blue moon means it was second full moon in the same month. This Lunar eclipse was visible from the all of Asia. From India we could not see the first half of the eclipse. When moon rose in our horizon it was almost began the totality of eclipse.

Many people do not find Lunar eclipse exciting as solar eclipse. There might be many reasons like time duration. Lunar eclipse runs for longer than solar eclipse. Solar eclipse produce far more marvelous views than Lunar eclipse. But, I think lunar eclipse is impressive by its own way. It also produce fantastic views, mine favorite is traveling of Earths shadow over lunar landscape. if we observe it through telescope it definitely make you excited. In total lunar eclipse moon never disappeared like sun does in solar eclipse. In fact moon become red in color when it goes to total phase.

        Moon was in total phase when rose in sky

When earth comes in between sun and moon, suns light do not get cut entirely. But due to to earth's atmosphere which stands almost 60 kilometer high turns some of the sun light towards moon. This redness is different in different eclipses. It also depend on the dust particle activities in atmosphere. If dust particle get more in atmosphere then moon color turns more deep red.

 

Earth's shadow shape can be seen here

                                          Last touch of earth's shadow:The eclipse getting over

We arranged event for observing this lunar eclipse with some government teachers and some community members also came. it was nice to have interaction with them. teachers showed full interest in this event. First time they were looking eclipse through telescope. However, we noticed that some of the community members hesitate to watch lunar eclipse. They might have thought that this can bring bad omen to them. We had discussion with them that there is no such thing like bad omen. But for grown ups its very hard to leave their notions.
Before, this eclipse we went to some schools in rural areas and discuss about eclipse with students over there. Students were more curious to know about such things. In my own experience I believe that young students can help us to work towards such myths rooted in society. They are open towards learning. they asks questions to at least their parents and relatives and make them to watch such events which people thinks bad.
Anyway, such events like eclipse gives us opportunity to go in common people and talks about the scientific thinking and rational against traditional thinking of religions and myths. It also help us to make dialogue on such issues and make people aware against false beliefs.