15 November 2016

Aldebaran occultation by Moon tonight

Most of you would have enjoyed the supermoon yesterday evening and most of you have taken wonderful photos. Today evening we have one more exciting astronomical event and that is occultation of star Aldebaran by Moon. Tonight moon will occult giant Aldebaran. since both objects are bright enough it will be easy to observe even with naked eye, a pair of binoculars and of course with telescopes. I would suggest you get all the setup ready before the given time and wait for the event rather than waiting until last minute. The chart below will be helpful to show the entry point and exit point of the star during occultation. 

Astronomers have used occultation to know about the size, shape and distance of the objects. Aldebaran is the brightest star in the constellation of Taurus, it is at a distance of 65 light years from Sun. By measuring the time taken for that star from disappearing and reappearing and getting reports from different parts of the world we get a pretty good idea of the shape of the object. Today evening moon will occult Aldebaran from the south near the crater Tycho. Use the chart below to follow the star from disappearance to its re emergence. Try and measure the time taken between the star disappearance and re emergence using stop watch. All the best and hoping for clear skies. 

Time of disappearance 15:26:46 UT
Time of re emergence 15:57:45 UT

 Moon in the constellation of Taurus and close to star Aldebaran.

Moon about to Occult the star.

Aldebaran re emerging after Occultation.

14 November 2016

A Hype called Super Moon:

I am sure you have come across this Super Moon through print media, TV Channels, blogs, Face Book, Twitter or through friends. Today's Full moon will be the closest in 70 year and if you miss it now, you will have to wait until 2034 for next Super Moon. Moon in its orbit around earth come close to earth and this is called Perigee and moves farthest from earth called Apogee every month. Perigee can happen at any phase of the moon, it may be in Crescent, Half or gibbous phase. When Perigee and Full moon phase coincides, the name given is Super Moon.

What to Expect?

Looking at this picture of Moon can you tell if the Moon is bigger or smaller? 

You will agree just by looking at the picture its not possible, you will need reference, something to compare with or measure the size. This is the same thing that will happen when you go out tomorrow and look at the Moon. Lets for a moment see the numbers involved. This month perigee distance is close to 3,56,509 km and when we compare this with last perigee month's perigee in the month of October, distance which was close to 3,57,861 km the difference is just 1352 km. This when we convert it to angle subtended by moon in the sky and the difference from two perigee is 0.127 arc minutes. This as you can imagine is not possible to notice just by looking. You may need to photograph this full Moon and take photographs of upcoming full moons with the same settings and compare the difference.

This is also the implies to the brightness of the moon today. If we have not really observed the moon form some time it will not be evident to casual observer the difference in brightness in this light polluted conditions.

I would suggest that people should observe the moon not during full moon, but to observe in crescent to half moon and take guidance from local astronomy group. If you come to ABAA on any Sunday evening, you can learn about night sky and also when there is moon in the sky you can use our telescope and learn to observe moon and other celestial objects.