The understanding night sky is essential for every astronomer. Here is TelescopeStargazer.com’s short guide to sky and basic astronomy.
In the ancient times, shepherds and mariners could study and understand the sky. For most of us, this is not possible due to a polluted atmosphere and living under roofed structures, which means that we do not get a naturally clear view of stars. Nonetheless, even at the moment when we, as amateurs, have a clear view, we are still unable to discern much apart from noting that numerous stars are up there.
We can understand the night sky if we comprehend how the shape of our planet and its movement affect our view of the night sky. This will allow you to visualize how stars travel across the sky, as well as know where to look for specific planets and even certain constellations of stars. You will also understand how latitude affects your view, and why certain constellations are only visible at specific dates and times. Understanding “how the sky works” is essential for every amateur astronomer, so let’s take a closer look what is going on up there!
Sky Changes Daily
If you observe the sky for a short duration of time, for instance, 30 minutes, you are unlikely to notice any changes. However, if the sky is observed for hours during night-time, you will notice a lot of changes. To begin with, you will be able to observe stars moving across the night sky as a single formation.
Our planet rotates on its own axis, and it spins from the west towards the east, and as the earth spins towards any heavenly body, including a star, it gradually comes into view and as the earth spins away from it, the body gradually disappears from view. Like the moon and sun, stars are observed to rise in the east and then set in the west.
Nonetheless, you can not see all the stars rise and set. This is because your view of the stars is determined by the latitude of your location. For instance, if you are in the Southernmost part of Australia, you can see the Southern Cross constellation of stars move in a circle in the night sky. In reality, the stars are not the ones circling the night sky, it is we, as earth inhabitants, who are spinning. The explanation for this phenomenon is provided hereafter.
The earth has a north pole and south pole. When you are standing in either pole and observe the night sky, you will the stars circling the sky. This is because the earth rotational axis runs from the north pole to the south pole, and people located in either pole will always see the night sky circling above them. If you are at the south pole, the point directly overhead in the sky is called the celestial south pole, and the stars are always observed to be circling the night sky, neither rising nor setting.
If you are located at the equator, you will observe a different night sky as compared to those living in either pole. The rotational axis of the earth is set at right angles to the equator. This means that if you are at the equator, you will observe the stars rise and move in a straight path across the night sky before setting in the west. However, you can never see the stars circling in the sky above.
It is therefore evident that the latitude of your location determines your view of the stars above. This also applies to people living in places located between the equator and either pole. In this places, the latitude determines how you will see the trajectory of the star across the night sky with those in the southernmost latitudes viewing circling stars while those near the equator viewing the stars moving in a relatively straight path.
Therefore in Southern Australia, you are near the poles but are at an angle (not a right angle) to the rotational axis. This means that you will see the stars move across the sky by they will not pass straight overhead. As the stars rise, they appear to move further north, and when they are setting, they appear to move further south. In other words, the stars travel across the night sky at an angle when viewed from the ground.
You can also observe planets in the night sky. All the planets in the solar system orbit around the stationary sun in the same plane and their orbital paths around the sun are collectively referred to an ecliptic. For star watchers, knowing the path of the sun during the day allows them to locate and observe the different planets in the night sky.
Watch: Understanding The Night Sky video:
Sky Changes during a Year
Our planet orbits around the sun, and this means that during different months of the year, we will see different parts of our universe. This means that our sky changes as the year progress. This also means that constellations of stars that are located in different parts of the universe can only be viewed during specific periods of the year.
Even so, if you observe the sky for six months from the same place, you will note that some constellations have disappeared while others have appeared. You will also see some constellations for the entire duration of six months, which correspond to half the duration that earth orbits the sun.
The zodiac constellations consist of 12-star constellations that are in the same plane, and can, therefore, be viewed, just like the sun and planets, from anywhere on earth. This explains their popularity in ancient cultures where astrology was prominent. These constellations also span the entire breadth of the sky, and you can therefore never view all of them at any particular time or season.
However, at any time of the year, you can always observe at least 4 zodiacs in the night sky. As the earth rotates, you will see the zodiacs rise in the east and as the night progresses you will see more and more zodiacs coming into view (sometimes up to 10), before they disappear as they set in the west. Therefore, understanding the sequence of the zodiac constellations as they rise across the night sky will allow you to spot your desired constellation.
As mentioned earlier, latitude affects your view of the night sky. Still, people located at the same latitude will have the same view of the sky. For example, people in Adelaide in Australia and those in Santiago, Chile, have the same view of the night sky, and they see the same constellations, despite being located thousands of miles apart.
However, people in the same longitude have different views of the sky because are located at different distances from the equator. For example, people in Adelaide in Australia and those in Tokyo, Japan, have different views of the night sky, and they, therefore, see different constellations, despite being located at the same longitude.
Observing stars with optics
Of course, it is possible to observe stars and planets using naked eyes. However, if you want to get closer, more detailed view, you will need some kind of optics. The good choice is for beginner amateur astronomer is for example Celestron 71020 SkyMaster Binoculars. Those give amazing view of the sky, and it is quite easy to carry. If you want go the step further, the excellent choice is Orion 8944 SkyQuest XT6 Telescope. Compared to binoculars, it gives much more detailed view of celestial bodies. Be sure to read also our telescope buying guide.
If you have any questions or comments about the how the night sky works, please leave a reply below!
Hopefully, this was helpful for understanding how things work at the sky!