Astronomical observations #7 : Deep sky objects - Introduction

in #steemstem6 years ago

Hello. After the planets, the time has come for the rest. Planets are able to see even from the city center, while deep objects can be seen only from the dark, rural sky. But believe me, it's worth going out of town with a telescope.


By NASA link [Public domain]

What are deep sky objects? They are all kinds of nebulae, star clusters and galaxies. They are more demanding in observations from planets, but actually the planets themselves are boring to an experienced observer. A large telescope is purchased precisely for viewing distant objects, which in the sky we have hundreds of times more than planets. Already the 8 "telescope (200 mm) and the village away from big cities about 30 km gives us the opportunity to observe the wonderful space. Unfortunately, I must disappoint you a bit. In amateur telescopes, you will only see the colors on the planets! The objects of the deep sky are too weak for our human eyes to see their colors in real time. The photos at the beginning of the article are the result of astrophotography, i.e. photos with a long exposure time, where the camera collects low light of the nebula or galaxy even for several hours! Then, beautiful colored objects appear in the picture. So we have black and white views. Note the low surface brightness of the deep sky objects. Brighter planets are small points with magnitude from -4 mag (Venus) to +2 mag (Mars most of the time). The brightest nebula has a brightness of about +4 magicians and isn't a point. It takes up as many as two discs of the moon in the sky! Think about how weak the objects are. You don't need to zoom in here, because most deep sky objects are simply large objects. We need as much light as possible, i.e. a telescope with the largest diameter and dark sky, so that the object doesn't blend with the background of the bright sky.

It seems to you that the game isn't worth the candle? Take a look at some astro rally. Look at what it looks like with your own eyes. Believe that seeing such distant objects is something amazing. There have been occasions when an astro amateur watching a distant galaxy saw that a very bright star suddenly appeared in it - he thus discovered a supernova in another galaxy. We see these objects as they were millions of years ago. However, maybe we will be lucky and the light of a great event from the past will reach us just when we look at the sky. In the following parts I will describe you specific objects of the deep sky.

Greetings to lovers of Astronomy!

Sources:

Deep-sky object
Nebula
Star cluster
Galaxy
and my knowledge...

All rights reserved by @astromaniac 2018

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