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Hobbies & interests

By Mohan Babu

seven sisters pleiades nebula
Orion constellation

It always takes some time for a baby to learn its first steps. The astronomy hobby can also be baffling at the start. Staying awake at night could be a challenge for some. On top of it, one has to fight the winter chill while watching the night sky. When we look up, we may look at thousands of identical stars and we may not know how to differentiate one from the other. We would simply not know how to get started. If we can overcome these initial challenges, then we can really start enjoying this hobby.

Constellations are groups of stars meant to aid night sky watching and for navigational purposes. Constellations are named usually after some recognizable shapes like scorpion or libra (scale). The moment we can identify one group of stars, we can locate many others by seeing their angular distance and direction. The easiest star grouping that we all can appreciate is Orion, the hunter. One would not miss the four bright stars forming the four edges of a rectangle.The three bright stars arranged in a line in the middle form the belt of the hunter.

Once we have spotted Orion, we should be able to find the other stars easily with the help of applications available in most iphones and smartphones. It is still better to understand the concept behind equatorial coordinates. This is an important tool to understand the position of stars and planets in night sky. The east-west directions are expressed in hours, minutes and seconds (From 0 to 24 hours). This is also called Right ascension (RA), a measure of angular distance in east-to-west direction. The North-South directions are expressed as declination (from 90 degrees North to 90 degrees South).

The bright red star on the bottom left in that picture is the star "Betelgeuse". It is having the equatorial coordinates of RA 5 h 55 mins and 7 degree north. Assume you want to find another star with RA 4 h 55 mins and 17 degree north. Twenty four hours make a day and that corresponds to 360 degrees in the night sky. So one hour would be equal to 15 degrees. Since the unknown star we like to check is one hour ahead of Betelgeuse, we should look at an angular distance of 15 degrees west and 10 degrees North of Betelguese.

How do we know the exact extent of ten degrees in night sky? Stretch your arm and look through your closed fist. The two ends of the closed fist is approximately equal to ten degrees. This should be a simple enough measure, right? So dive into night sky and learn swimming through the stars.

Learning to navigate night sky

Understanding equatorial coordinates