Planets and the moons are not the only things astronomers intend to observe in the sky. Stars are always mysterious that can reveal dramatic detail even with a 4-inch telescope. The sun is the nearest star to us and also the only night sky object that may cause harm to our eyes.
Observing the Sun can burn the retina of your eye and make it blind even if you take a glimpse of it without proper protection. You need to block more than 99% of the sunlight before it gets into your eyes.
Quick Guide to Observe the Sun
The sun is best viewed in the morning or late afternoon when it is cooler and there is less chance that its brightness would injure your eyes. Use a telescope with an aperture of 2-4 inches. When studying the sun, make sure the filter is securely fastened in front of the telescope so that wind or jerks cannot cause it to move. Direct viewing through a telescope while wearing a suitable filter and projecting the picture of the Sun onto paper are two safe ways to observe the Sun.
Two Safe Methods to view the Sun:
1. Direct Viewing using a proper filter in front of a telescope
Aperture filters can provide a risk-free view of the sun protecting eyes from both visible and invisible radiations and the telescope from excessive heat. Two kinds of aperture filters are available on the market. Metalized Mylar plastic aperture filters are cheap but it makes the solar view blue. In contrast, filters made of metal on glass deliver a natural look but cost more.
However, the best filters are metal-coated on glass or Mylar on both sides. They prevent the sunlight from getting into the mini scratches and the pinhole to provide extra protection to your eyes from these unwanted rays.
2. Projecting the image of the Sun on a piece of paper
Photo: Projection Method to view the sun
Hold a white paper or card around 1-2 feet behind the eyepiece of the telescope. Shade the paper to get a better image. Focus the lens of the telescope until you get the sharpest image. You will find almost all the details in the image including the sunspot. The advantage of this method is you can mark the spots on the image and preserve them as records for further use in the next observation.
Photo: The image of the sun using the projection method
What is the best time to observe the Sun?
- Choosing the best time is a part of taking protection while observing the sun. The best time to view the sun is the morning or afternoon time when the heat is less as the possibility of the brightness of the sun harming your eyes is also less. Besides, the motion of air due to heat from sunlight may cause distortion in the view through the telescope. In most locations, you will find that morning is the best time. But somewhere like near mountains, mountains heat up early in the morning and make air unstable which means afternoon is the best time to view the sun in that type of area.
- Another safest and best time to view the sun is seconds just before and after the totality during a solar eclipse. You need some safety and precaution throughout the whole time of a solar eclipse except the time immediately before totality when the last vestige of sunlight disappears and the corona becomes visible like a diamond ring. This time is known as Baily’s Beads. Only at this moment, you can remove filters from your telescope for a few seconds. You have to be extremely careful as you do not have a long time to observe the sun like this without protection. It is safe until the second diamond ring appears. You will be able to see the reddish chromosphere just after the first diamond ring disappears but it lasts only for a second. And it is the only time you can identify the chromosphere without the Hα filter. You will also see the solar prominences and observe the corona’s overall configuration. But be prepared to close or retract your eyes and telescope at the moment the second diamond ring vanishes.
How to set up a telescope to observe the Sun?
Step 1: Choose the correct eyepiece
2-3 inches of the aperture is enough for a telescope to view the sun. Use a low-power eyepiece. If your telescope has a large aperture, make it smaller by cutting down a circular hole in cardboard and adjusting it in the front of the tube.
Step 2: Adjust the Solar filter
Take a solar filter and adjust it in front of the lens. It will block the intense sunlight making the image pretty neat. You will be able to see the sunspot too. Without the solar filter, you cannot keep your eyes on the eyepiece or put a phone camera there as it is extremely harmful to both your eyes and the camera.
Step 3: Align the Finder Scope
Take the scope and turn it around where the sun remains. You just can follow the shadow of any object. Sun is right in the opposite direction of the shadow. Then look through your telescope and align it. It is better to use a solar finderscope that will center the Sun in the eyepiece. H-alpha scope includes solar finderscope. However, they are sold separately too. Keep in mind that we do not look through the solar filterscope like traditional finderscopes. Rather, move the tube till its shadow on the ground becomes smallest. There is a pinhole in front of the finder that projects the solar disk on the panel at the back. You have to align the white dot on the back of the finder with the pinhole projection. Now your telescope is ready for solar observation.
What can you see on the Sun with a telescope?
- The dark spots or areas on the bright surface of the sun are known as Sunspots. Most large sunspots have a darker central part called the ‘dark umbra’ and a lighter gray part at the edge named ‘the penumbra’. At high resolution, the thin radiation from penumbra named fibrils can be seen. The small sunspots are called pores which lack penumbras.
- Sunspots are generally formed in pairs. Sunspots are the origin or end points of the magnetic field loops that bend above the surface. If you see a pore in a clear area of the sun’s surface, it gives a sign that a group of sunspots is going to produce within a few days. Pores either die in one or two days or grow and make a penumbra.
- You may also find more spots appearing nearby. They can bloom fully in just 10 days making a complex ‘active region’ from east to west.
- If you conduct observation regularly, you will find that the eastern spot disappears earlier than the western spot.
- You will understand the rotation of the sun if you draw sunspots several times a week.
- In the disk of the sun, you will find that the outer region is darker than the central area proving that the sun has an atmosphere.
- The large bright patches near active areas are called faculae. If they are spotted in a clear area, it means that a spot group has disappeared recently.
- With a 4-inch aperture and high magnification, granulation or granules will be visible. Granules are convection cells that appear due to constant boiling up of the hot gas on the surface of the sun persisting for around 5-10 minutes.
- White-light flares are rare but visible.
- Dark faculae at the middle of the sun’s disk.
Tips and Precautions to observe the Sun in the best way:
- To test your filter, hold the filter up pointing towards the sun. If bright pinpoints are visible, fix it with opaque paint or reject this.
- Make sure the filter is well attached in front of the telescope, so that wind or jerk can not move it when you are observing the sun.
- Use a telescope with 2-4 inches of aperture. A large aperture will cause too much light and heat to pass through the tube and may damage the eyepiece and other optical elements in the tube. The excessive heat will destroy the clear cement between the eyepiece lens elements. One of the best eyepieces for solar observation is Huygens or Ramsden as they have no cement in the lenses.
What telescope to see the Sun?
Sky-Watcher Virtuoso, Meade Coronado Personal Solar Telescope, Lunt LS50, and Lunt LS60 are great telescopes to see the Sun. A list of telescopes has more telescope options that can see the Sun very clearly.
What size telescope to see the Sun?
A telescope with a 2-4 inches aperture is enough to show sunspots in several safe methods. But the large apertures reveal more sharp details of the sun. If you use telescopes with an aperture larger than 4 inches, use an opaque mask in front of the lens with a 3-4 inch hole on it. It is safe like the low aperture telescopes and at a time provides the best images of the sun.
What magnification is required to see the Sun?
The sun can be viewed with 50x magnification. Telescopes with large apertures will allow more magnification providing more solar features. Make sure you use a safety mask in front of the tube.
What filters are available to see the Sun?
- White-light filters or Aperture filters are made of metal-coated glass or Mylar and can block more than 99% of sunlight.
- Hydrogen-alpha filters are widely used in solar observation. They can show the photosphere in its natural white color. The disk will look pale orange or blue or yellow depending on the type of filter.
- Calcium-K solar filters can take you into next-generation solar observation.
Enjoying the Sun? Here are other things to see with a telescope.
The sun is not the only star you can see through your telescope. With proper aperture and magnification, you can see a lot of star clusters like Omega Centauri (NGC 5139), the Jewel Box (NGC 4755), and more. Moreover, there are a lot of night sky objects like galaxies, nebulae, etc. The List of things to see with a telescope provides the shortlist of night sky objects observable through a telescope.