You don't need to wait until nightfall to go stargazing.
Each day the sun — our yellow dwarf star– rises in the east and sets in the west, but have you ever looked at it up close? About 93 million miles from Earth, the sun is a 4.5 billion-year-old ball of hydrogen and helium that demands a closer look.
From sunspots on its ever-changing surface to incredible phenomena visible only during a total solar eclipse, the sun is a skywatching target like no other, yet solar observing demands great care.
Related: Night sky guide (what you can see and when)
Jamie Carter is an experienced science, technology and travel journalist. He is the editor of WhenIsTheNextEclipse.com and author of A Stargazing Program For Beginners.
Why it's important to observe the sun safely
Except during the brief total phase of a total solar eclipse when the moon obscures the sun, never look at the sun without proper eye protection. It is never safe to look directly at the sun's rays even if the sun is partly obscured because they contain harmful ultraviolet (UV) and infrared (IR) rays that can damage your eye's retina and even cause blindness.
Never use regular sunglasses to observe the sun. The only safe way to look directly at the sun is through specifically designed solar filters, using solar eclipse glasses for direct viewing and solar filters for telescopes and binoculars.
How to observe the sun with eclipse glasses
According to the American Astronomical Society (AAS) here's how to use solar eclipse glasses:
- Inspect your solar filter before use. If they're scratched, discard them.
- Always supervise children using solar filters.
- If you wear glasses then put solar eclipse glasses over them.
- Cover your eyes with your eclipse glasses before looking at the sun and look away from the sun before removing them.
The most common mistake people make when using solar eclipse glasses is to wear them like glasses. Despite their design, the thin cardboard arms on eclipse glasses make them prone to falling off. That can be dangerous if you're looking at the sun at the time. So the best way is to wear them like glasses but while doing so keep the temples pressed against the side of your head using both hands.
However, you should never observe the sun through a telescope or binoculars while wearing eclipse glasses. Optical equipment magnifies the sun's harmful rays unless there's a solar filter in the way at the sun-facing end of the instrument.
How to observe the sun with a telescope
If you want a close-up of the sun the best way is to use a telescope. However, never look through a telescope without a solar filter on the large end (the objective lens). One way is to purchase a white light solar filter, which blocks 99.999% of sunlight — including dangerous UV and IR light — and is designed to view sunspots as dark regions of the surface of the sun as well as the solar photosphere. The view is typically either bluish-white or yellow, depending on the materials used.
Another way is Hydrogen-alpha (Hα) filters, which instead of sunspots show prominences and other details on the sun's surface. Hα filters do that by only allowing through light from hydrogen atoms. Both white light and Hα solar filters for telescopes come in all shapes and sizes to fit all kinds of telescopes. It's even possible to buy Hα telescopes with integrated filters for 100% solar viewing.
If you're looking for a telescope to view the sun our best telescopes guide can help point you in the right direction. We also have a guide to the best budget telescopes under $500 for those wanting to invest in new equipment without breaking the bank.
How to observe the sun with binoculars
There are two ways of observing the sun when using binoculars. As with a telescope you must put solar filters on the objective lenses on the front of binoculars (and never the eyepieces). The most common way to do this is to purchase solar filter film from reputable brands. The other way of observing the sun with binoculars is to buy some special sunoculars, which have solar filters built-in. You get a magnified view of the entire solar disk, though since the solar filters are built-in they're safe, but lack versatility. Well-known models include Lunt SUNoculars and Celestron EclipSmart.
Our best binoculars guide will help you scope out the best astronomy binoculars available for stargazing and what you should be looking for when choosing the right pair for you.
How to buy safe solar eclipse glasses and solar filters
These manufacturers sell reliable solar eclipse glasses and solar filters that comply with the transmission requirements of the ISO 12312-2 international standard. Some also sell solar film for DIY projects, such as making custom-fit solar filters for telescopes and binoculars.
Other ways to observe the sun
Before solar eclipse glasses and solar filters were common, the safest way to observe the sun — particularly during an eclipse — was indirectly by using a pinhole camera that you can make easily at home.
For a larger projection, you can use a pair of (cheap, expendable) binoculars and a tripod to make a sun projector.
Another completely safe way to observe a partial solar eclipse safely is to look at the ground beneath trees. A partially eclipsed sun's light filtered through the leaves of a tree or other foliage projects tiny crescent suns onto the ground. For a similar effect, you can hold a kitchen colander or slotted spoon. Anything with small, well-defined holes will project crescent suns.
However, the safest way to observe the sun is online, with the Virtual Telescope Network and timeanddate.com frequently livestreaming solar eclipses. You can also observe (almost) real-time images of the sun from NASA's orbiting Solar Dynamic Observatory.
What to look for when observing the sun
Sunspots
The most common reason for studying the sun is to look for sunspots. Best seen through white light solar filters, sunspots are darkened patches on the sun caused by its magnetic field. Counting them is how astronomers monitor the sun's activity, which waxes and wanes across the solar cycle, which lasts roughly 11 years. They can appear quickly and evolve over a few hours or many days. Sunspots can be seen at any time of day and are also worth looking for during a partial solar eclipse.
Photosphere, chromosphere and solar prominences
The lowest layer of the sun's atmosphere, the photosphere is the innermost that can be observed outside of a total solar eclipse. Best seen through Hα solar filters as a red halo, it's where most of the sun's energy is emitted, including solar flares.
Also visible through Hα solar filters is the chromosphere, the region of the sun's atmosphere between the photosphere and corona. It's from here that you may see spot solar prominences (also called filaments), plasma and magnetic field structure that is visible as red arcs.
Transits of planets and satellites
The inner planets Venus and Mercury occasionally cross the sun as viewed from Earth. When that happens it's possible to observe a black dot appearing to cross the sun's disk. A good view demands a telescope wearing a solar filter, though it's a rare event to witness. Transits of Venus occur twice seven years apart, but with a gap of 105 years until the next pair. They will occur in December 2117 and 2125. Transits of Mercury are more common with the next one on November 12/13, 2032 then November 7, 2039. The most recent transit of Mercury was on November 11, 2019.
Your best chance of catching a transit is actually by watching the International Space Station (ISS) cross its disk. It can be calculated in advance using the ISS Transit Finder, but since it lasts less than a second you do need to have a camera using solar filters ideally mounted on a star-tracker.
Related: How to see and track the International Space Station (ISS)
What to look for when observing the sun during a total solar eclipse
The golden rule for all solar observing is to never look at the sun without proper eye protection except during the total phase of a total solar eclipse. Though care is required, during these rare and spectacular events is the only time you can see — with the naked eye — these phenomena. However, do remember that they are only visible during the brief minutes of totality, and not at all visible during partial or annular solar eclipses, for which you must wear solar eclipse glasses and use solar filters on optical equipment.
Related: Solar eclipses: When, where & how to see them
Solar corona
The naked eye target everyone is waiting for during a total solar eclipse is the solar corona, the sun's hotter, outer atmosphere. Only visible during the brief minutes of totality during a total solar eclipse, it's an incredible sight, appearing as a tenuous wispy, spiky, flower-like halo of white diffuse light around the moon. Incredibly, the corona is much hotter than the surface of the sun.
Baily's beads and the 'diamond ring'
As the first beads of sunlight glisten through the valleys of the moon, totality ceases. They coalesce into a fabulous 'diamond ring' as a burst of light appears. It's time to look away from the eclipsed sun and put your solar eclipse glasses back on. A few minutes earlier, before totality, a 'diamond ring' reduces down to Baily's beads, though since that happens at the moment a partial solar eclipse (which requires solar eclipse glasses) ends it's easy to miss.
Chromosphere and solar prominences
Visible during the first and last few moments of totality on opposite sides of the moon, the chromosphere looks a deep pink to the naked eye. It's worth studying through binoculars (with solar filters briefly removed during totality), not least because you may well spot solar prominences (also called filaments) visible to the naked eye as deep pinky-red arcs.
Additional resources
Want to look further ahead? You can find a concise summary of solar eclipses through 2030 on NASA's eclipse website or find the next eclipse for any location on Timeanddate.com. Read more about safely observing the sun and tracking its sunspots and flares on Sky & Telescope.
Bibliography
The Ultimate Guide to Observing the Sun. Celestron. Retrieved October 20, 2022, from https://www.celestron.com/blogs/knowledgebase/the-ultimate-guide-to-observing-the-sun
How to View a Solar Eclipse Safely. American Astronomical Society. Retrieved October 20, 2022, from https://eclipse.aas.org/eye-safety
What to look for & when during a total solar eclipse. Sky & Telescope. Retrieved October 20, 2022, from https://skyandtelescope.org/2017-total-solar-eclipse/what-to-look-for-when-total-solar-eclipse/
Reputable Vendors of Solar Filters & Viewers. American Astronomical Society. Retrieved October 20, 2022, from https://eclipse.aas.org/resources/solar-filters
How to View the 2017 Solar Eclipse Safely. NASA. Retrieved October 20, 2022, from https://eclipse2017.nasa.gov/safety
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