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How to See Sirius With A Telescope?

Photo: The Dogstar (Sirius A) and its Pup (Sirius B) 

Sirius, also known as the Dog star, is the brightest star in the sky found in late winter and spring. It has a tiny companion named Sirius B known as Pup which is basically a white dwarf star. Both of them make a binary star system that is visible through your telescope. Most of the time, they are seen combinedly as one glowing star as it is hard for the telescopes to detect their duality. 

The main star Sirius is twice as massive as the Sun whereas the dwarf star Sirius B is around the same volume as the Earth though has the same mass as the sun. Besides, the luminosity of Sirius B is 10,000 times less than Sirius A.

What is Sirius?

Sirius, also known as the “Dog Star,” is a binary star system located in the constellation Canis Major. It is the brightest star in the night sky, boasting a magnitude of -1.46, which is twice as bright as Canopus, the second brightest star. This luminosity, attributed to its intrinsic brightness and proximity to the Solar System, makes Sirius a prime target for telescopes of all sizes. Its white color with subtle undertones and a diameter of about 1.71 million kilometers render it an excellent subject for telescopes capable of observing in the ultraviolet spectrum. The primary star, Sirius A, is classified as a spectral type A1V, while its companion, Sirius B, is also visible through small amateur telescopes. At an approximate distance of 8.6 light years from Earth, Sirius is expected to draw closer over the next 60,000 years before receding and dimming. This celestial dance, with an orbital period of around 50.1 years, adds to the allure of observing Sirius through the lens of a telescope.
Sirius is a binary star system consisting of a main-sequence star, Sirius A, and a faint white dwarf companion, Sirius B. Sirius A is about twice as massive as the Sun and has an absolute visual magnitude of + 1.42, being 25 times more luminous than the Sun. The distance between Sirius A and Sirius B varies between 8.2 AU and 31.5 AU as they orbit each other every 50 years. The Sirius system is one of the nearest neighbors to Earth, being at a distance of 8.6 light-years / 2.64 parsecs away. The Sirius system is speculated to be between 200 to 300 million years old. Originally, the Sirius system was made up of two bluish stars but the more massive one, Sirius B, consumed its resources and became a red giant before shedding its outer layers and collapsing into its current state as a white dwarf around 120 million years ago. The star system has been known to the ancients for a long time, dating back to even 4,000 years ago by ancient Egyptians. The rising of Sirius marked the flooding of the Nile in Ancient Egypt and the “dog days” – hot days – of summer for the ancient Greeks. For the Polynesians, mostly in the Southern Hemisphere, the rising star marked the coming of winter and it was an important reference for their navigation around the Pacific Ocean. There are conflicting pieces of evidence that suggest Sirius appeared redder only 2,000 years ago.

How far is Sirius from planet Earth?

The space object Sirius is approximately 8.6 light-years away from planet Earth. The absolute magnitude of Sirius is 1.45, which signifies its intrinsic brightness. The key features of Sirius that make it a popular target for telescopes are its extreme brightness, proximity to Earth, and visibility from both hemispheres. The color of Sirius is white. Sirius serves as a reference point for aligning telescopes and other astronomical instruments, aiding in their calibration and adjustment for optimal viewing conditions. The visibility of Sirius from Earth can affect the choice of telescope for observing it, as a telescope with a large aperture, high magnification, and the ability to observe in the visible and near-infrared regions would be ideal for capturing detailed images of the bright star.

Can you see Sirius with a telescope?

Yes, Sirius is visible through a telescope. The recommended telescope size for viewing space object Sirius is at least 120mm aperture with a 1,000mm focal length. The magnitude of Sirius is -1.46, and its brightness makes it easily visible through a telescope. This type of telescope would provide a clear and magnified view of Sirius, which is known for its brightness and proximity to Earth. The best telescopes for viewing space object Sirius are the Celestron NexStar 8 SE Computerized Telescope, Orion Skyquest XT8, and Zhumell Z100 Altazimuth Reflector Telescope. Sirius can be seen with a telescope as small as 100mm, but the views are not sharp. An 8-inch telescope with at least 300x magnification can provide a clearer image. The best time to observe Sirius in the Northern Hemisphere is during the winter months, particularly January and February. A star map can be helpful in locating Sirius. Sirius B, the companion star of Sirius, can be seen with a 10-inch telescope using at least 500x magnification.

Quick Guide to Observe Sirius 

Select a star map before you begin; it will aid in observing Sirius. The majority of January and February, or the winter months, are the greatest times to watch Sirius B in the Northern Hemisphere. Even a 4-inch telescope will be able to see Sirius B by the 2030s. For a 6-inch telescope, use a 400x magnification, and for an 8-inch scope, a 300x magnification. First, try to find Orion. On top is Betelgeuse, a bright red star. You can find its renowned belt, which is made up of three brilliant stars, in the center. Just above the belt is Sirius. Follow the stars down and to the left. You will find Rigel, a distinctive bright star of blue-white color, there. Sirius and its companion Sirius B are nearby.

Before starting, choose a Star map, it will help with Sirius observation.

There are several star charts that can show you the location of Sirius that night. ‘Clear Sky Chart site’ is an app that helps you to find the best location near you to observe the star by analyzing the weather condition and airspeed. If it forecasts vigorous turbulence, there is no point to try. Plan for observation when the seeing forecast is merely good at least.

How to find Sirius A & Sirius B?

  1. Try to locate Orion at first. 
  2. Bright red Betelgeuse is on top.
  3. In the middle, you will find its famous belt composed of three bright stars. Sirius is just upward the belt.
  4. Follow the stars left and down. There you will get a distinct blue-white color bright star, Rigel. Nearby you will find Sirius and its companion Sirius B.
  5. Take a high-power eyepiece, adjust it in the scope, and point the tube towards. 

What is the best time to observe Sirius?

In the Northern Hemisphere, the best time to observe Sirius B is in most parts of January and February i.e in winter. During this time Sirius is at its highest in the sky in the early hours. It is important because the viewing experience could be worse when Sirius is too low in the sky due to turbulence near the horizon. On 1st January, the best time is at midnight, on 1st February, around 10 pm, and on 1st March at around 8 pm. As April comes, Sirius begins to get down shortly after sunset.

Photo: Separation between Sirius A and from Earth on a 50-year cycle.

The two stars orbit each other at around 20 AU (astronomical units) which is the same distance between the sun and Uranus. It is almost 3 to 11 arc seconds on a 50-year cycle. In this year 2022, these two are at their highest separation. So this last month of 2022, is the best time to see these two stars and look for them after midnight. 

3 Tips to observe Sirius in the best way.

  • Sirius B will be visible throughout the decade the 2030s, with even a 4-inch telescope. 
  • Theoretically, Sirius B is just outside the bundle of the brightness of Sirius A. However, in reality, it is mostly hidden by the glare of Sirius. But for a few moments, you will be able to see the round pattern of Sirius B.
  • If your eyes get tired of searching for Sirius B, take a break and observe the other stars and then try again. If you can not see it, try again the next day.

What can you see on the Sirius with a telescope?

  • You will find another binary star Rigel and its companion Rigel B.
  • Sirius B or the Pup is right there. 
  • Alnitak (Zeta), Alnilam (Epsilon), and Mintaka (Delta)are the three bright stars on the belt of Orion.

What telescope to see Sirius?

Celestron RASA 8″, Meade LX200-ACF 8″ f/10 Telescope, and Orion SkyQuest XT8 Classic Dobsonian are great telescopes to see Sirius. A list of telescopes has more telescope options that can see Sirius very clearly.

What size telescope to see Sirius?

With a 100mm telescope, you can spot Sirius but the views are not sharp. An 8-inch telescope with at least 300x magnification can make a great image of Sirius. But to detect the Pup, you need a 10-inch telescope with at least 500x magnification. The larger scopes will show sharper images.

What magnification is required to see Sirius?

You should try the highest power available on your telescope. Use 300x magnification for a 6-inch telescope and 400x magnification for an 8-inch scope. Use more magnification for the larger scope.

Enjoying Sirius? Here are other things to see with your telescope

Viewing Sirius through a telescope is an amazing experience. However, your telescope can show you more gems of the night sky. All the planets of our solar system, the sun, satellites, asteroids, comets, stars, nebula, and myriad night sky objects are waiting for you to show their amazing appearance. Grab a telescope and hunt for them. ‘List of things to see with a telescope’ can be a guide to knowing where and how to find different objects with your telescope.

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