Spotting Sirius in broad daylight may be easier than you think! Here's how to do it.

Stellar king
Sirius is the brightest star in the night sky and visible in daylight under the right conditions.
Bob King

In late February, the waning Moon passed just north of Jupiter, making for a great opportunity to find the planet in the daytime sky. Although I couldn't see it with the naked eye at the time, I easily found it in 10×50 binoculars a couple degrees south of the Moon more than an hour after sunrise.

That got me thinking about Sirius. I'd always heard it could be seen in the daytime sky if you knew exactly where to look and picked the opportune time. Quadrature is best, when Sirius stands on the meridian at sunrise or sunset. Morning quadrature occurs in early October and evening quadrature in late March. In other words, one of the best opportunities is happening right now.

Next, I chatted online with British observer Colin Henshaw who sent me a link to his British Astronomical Association paper describing his first observations of Sirius in October 1981 and March 1982, made under ideal conditions from Zimbabwe. Ideal because they were made at both quadratures with the star passing near the zenith. Morning attempts at seeing Sirius are more advantageous because you have the benefit of finding the star in a dark sky and following it past sunrise. It's trickier in the evening because you have to fish the star from invisibility out of a bright sky.

Duluth, Minnesota, (my location) at +47° north latitude is no Zimbabwe (–19° south)! Sirius culminates at an altitude of 26°, which means atmospheric extinction reduces its brightness by half a magnitude from –1.5 to –1.0. At least for me, it might make more sense to begin my attempt before quadrature when Sirius stood further from the Sun in the southeastern sky. I'd lose a few degrees of altitude but gain a slightly darker blue sky.

Daytime appearance!
Sirius, photographed one minute before sunset from Duluth, Minnesota. I used the tree to "point" to the star in the barren, blue sky. To see Sirius with the Sun still up, clean, haze-free skies are a must.
Bob King

On March 3rd, the star was in just the right spot to make an attempt before sunset. I knew Sirius's altitude and exact direction beforehand and pointed 10×50 binoculars at the location. After less than a half-minute of searching, a perfectly white spark of light jumped out of the blue — Sirius! And it was still 20 minutes before sunset. I lined it up directly over a nearby spruce tree so I would know exactly where to look and stared. And stared. Finally, two minutes before sundown and just in the nick of time, bingo! My first naked-eye star in daylight.

If I can see it, you can, too, especially if you live further south where Sirius stands higher in the sky. Now through the end of March is the best time for mid-northern latitude observers to attempt this challenge because the star reaches evening quadrature about March 27th. Thereafter, it moves ever closer toward the Sun and into brighter sky.

While not critical, it really helps to have a planetarium-style program (or phone app — links below) at your fingertips. I use Stellarium, a free program for both Mac and PC. Download and open, then select your city from a list of locations. Find your sunset time with this sunrise-sunset calculator and key that time and date into Stellarium.

To pinpoint Sirius, you'll need two numbers: its altitude and azimuth about 10 minutes before sunset (or whichever time you choose). You can either click on the star and read out those details in the legend at the upper left of your screen or click the Azimuthal Grid icon (looks like a bullseye) in the row of shortcuts at the bottom of the screen. A grid will appear with azimuths and altitudes like the one below. I also used the Compass Marks feature (gradation icon) in that same row of shortcuts. Press it and the horizon will be marked off in individual degrees of azimuth.

Getting it on the grid
This is the Stellarium layout I used to guide me to Sirius. Lines show altitude and azimuth. I selected a flat horizon ("ocean" setting). Individual degrees of azimuth tick along the bottom of the horizon. Click to enlarge.
Stellarium

Now that you know Sirius's precise direction and altitude, grab a compass and binoculars and head outside to a spot with a good view to the south-southeast. It helps to pick a place where there's something in the foreground you can use to line up the star, otherwise you'll literally be lost in the blue. I used a nearby tree and stood where Sirius shone directly above it. You also could use a building, a power pole, or roof line.

Ecliptic pals
Finding bright planets is easier in daylight thanks to the Moon. Jupiter and the Moon pair up on February 27, 2019, 80 minutes after sunrise. 
Bob King

Two final details. True north varies from compass or magnetic north by several degrees depending upon your location. The difference is called magnetic declination. Mine is only about 1°, so I ignored it, but yours may be larger. You can check your magnetic declination here and factor it in if needed. Also, make sure your binoculars are pre-focused at infinity. If they're not, Sirius will be out of focus and much more difficult to spot. Good news — the crescent Moon returns to view starting about March 8th.

Know your heading
Close-up of a compass showing azimuth readings.
Bob King

Focus on the Moon, a cloud, or on the stars the night before, and you'll be golden. Then point the compass north and find the azimuth you determined for Sirius on the outer ring. That's the exact direction to look for the star. Use your fist or fingers to estimate the altitude you calculated for the Sirius. Ball your fist (vertically) and extend it at arm's length with the bottom touching the horizon and measure upwards. One fist equals 10°, an extended little finger 1°.

I went out about 20 minutes before sunset. Once you find Sirius in binoculars, align it with your reference point, noting its height and relation to it. Then lower the binoculars and give it a go with just your eyes. I had no luck seeing even a hint of the star until several minutes before sundown. At the two minute mark, it quickly popped in and out of view, but I was unable to hold it steady. One minute before sunset, I could briefly hold the star steady. At the moment of sunset, Sirius was obvious. So much happened in the final three minutes, the experience practically left me breathless.

If you're older, you'll have trouble with pesky floaters, the dark spots inside your eyeball that float downward when looking up at the sky. Against the featureless blue, they can be annoying. I tipped my head left and right a few times to clear my vision while searching for the star. I also looked away and relaxed my eyes by changing their focus. But the best technique was simply to find my inner calm and relax. Who knew one had to bring so much to the table to see two stars in the sky at one time?

Good luck finding Sirius! I'd love to hear your report, positive or negative.

Sirius update: I recently wrote about the occultation of Sirius by the asteroid 4388 Jürgenstock on February 18-19. Like you, I was eager to hear of any positive results, but so far only a few negative results were recorded. If you hear of anyone who witnessed it please let us know in the comments area.

Tags

Sirius

Comments


Image of Tom-Reiland

Tom-Reiland

March 6, 2019 at 6:05 pm

Bob, I'm glad you wrote about this observing challenge. It's been at least a decade or more since I tried this. I have accomplished this observing feat in the morning and the evening. I think it's easier to do it in the late Summer and Autumn because you can observe Sirius in the morning twilight until after Sunrise. Using a building, trees or a hill to block the Sun is a good idea. I keep a list of celestial objects that I have seen while the Sun is in the sky. Besides the Moon, Venus, Jupiter and Mars (at it's closest opposition), I've seen one meteor/fireball and an Iridium satellite. It's become harder to try this because of floaters in my eyes and other changes to my eyes due to aging.

You must be logged in to post a comment.

Image of Bob King

Bob King

March 6, 2019 at 7:14 pm

Tom,
Boy, do I ever understand the floater issue. Like I said, I tilted my head this way and that to clear my vision. It really helps! Good luck — I know you'll spot it.

You must be logged in to post a comment.

Image of Larry-Sessions

Larry-Sessions

March 6, 2019 at 6:08 pm

Hey, Bob. I've been interested in such topics for more than 40 years, and in fact wrote a literature paper on it decades ago. The idea was seeing stars from the bottom of a well and similar feats. The conclusion at the time was that it was not possible. Now I am not saying that you are completely filled chock full of wild blueberry muffins, but viewing any star, naked eye, in the daytime is a highly problematic situation. The difference between photographing a star, such as Sirius, in the daytime and actually observing it in the daytime with the unaided eye are completely different things.

As you have indicated, very shortly before sunset or right after sunrise are the best times to try, and especially when the star is roughly 90 degrees away from the Sun at those times (and near culmination of the star). Without a nearby "landmark" such as a quarter Moon (or your tree), I would say any such reported observation is suspect, perhaps the result of straining the eye to its limits.

I have been doing such observations for decades. My eyes used to be excellent, but age is wreaking havoc, and I am no longer sure what they are capable of observing. However, I have observed Venus numerous times and even Jupiter 2 or 3 times. in daylight, unaided eye. I have written about it in either S&T or Astronomy (can't remember now --age, you know). I do know of someone who has claimed, reasonably I think, to have seen Mars with the unaided eye after sunrise. However, I have never seen Sirius or any other star in the daytime. Assuming that you have not made a mistake in your identification, I would have to say that you have remarkable eyesight.

You must be logged in to post a comment.

Image of Bob King

Bob King

March 6, 2019 at 7:13 pm

Hi Larry,
I understand your skepticism. I'm also a skeptical observer also and would never have chosen to write about the topic unless I'd seen Sirius myself. Did you read Colin Henshaw's observation? I included the link in the blog.

By very good fortune, we had exceptional skies this evening (March 6). I just got in after attempting the observation again. This time, after having becoming more familiar with what to look for, I was able to see Sirius fully 4 minutes before sunset. It certainly difficult at that time. But two minutes before sundown, I held it steadily and it was readily seen. Just no question about it. One minute before sunset, and it was even easier. Of course easy is a relative term! But there was no question of seeing it. It looks like a pale spark or twinkle in the blue. The last 3-4 minutes before sunset are the crucial times — at least for my latitude. I would encourage you to try for Sirius again if you can. You might be pleasantly surprised.

PS. I made the photo to document it and to show how relatively easy it is to capture the star with a camera.

You must be logged in to post a comment.

Image of Larry-Sessions

Larry-Sessions

March 7, 2019 at 10:46 am

Well, it is a remarkable feat and I applaud you and anyone who has done it. Now I have to figure out when and where my article (re: daytime planets) came out back in the 80s.

You must be logged in to post a comment.

Image of Bob King

Bob King

March 7, 2019 at 2:47 pm

Thank you, Larry. If you find your paper, please send me the link.

You must be logged in to post a comment.

Image of Larry McNish

Larry McNish

March 7, 2019 at 12:34 pm

Using polarized sunglasses or a polarized filter on your scope / binoculars makes it easier.
Long 2008 article on this at: http://calgary.rasc.ca/daystars/index.htm

You must be logged in to post a comment.

Image of Bob King

Bob King

March 7, 2019 at 2:51 pm

Thanks, Larry for the link and list! I've observed several of those objects with binoculars or a scope in the daytime. I'm not sure a polarizing filter would help in naked-eye star sightings because they would dim the star's light, but who knows? I'll have to try it the next time I look for Sirius.

You must be logged in to post a comment.

Image of John-Cudworth

John-Cudworth

March 8, 2019 at 3:03 pm

I saw Venus near the moon in December 2018 at 11am on a clear day. I have heard Mercury can be seen with the sun up also , but the surface brightness is lower. If the object is at quadrature , a polarizing filter darkens the sky more, than the object because the air polarizes the light , so the contrast against the sky is greater.

You must be logged in to post a comment.

Image of John-Cudworth

John-Cudworth

March 8, 2019 at 3:04 pm

Definitely worth trying.

You must be logged in to post a comment.

Image of Gordon-Strader

Gordon-Strader

March 9, 2019 at 2:13 am

I saw Venus several years ago in late in the morning. My first officer and I were west bound near Spokane, WA watching a southbound 747 several thousand feet above us passing overhead leaving a contrail. The FO noticed something white looking like it had fallen off the 747. By an odd coincidence, from our perspective, the jumbo passed thru the spot where Venus was and our motion and that of the 747 made Venus look like a part had left the other aircraft. It didn't take long to notice the "part" was holding it's position in the sky and a quick check on Starwalk verified it was Venus we were looking at.

You must be logged in to post a comment.

Image of relh

relh

March 8, 2019 at 6:18 pm

It might not be nessary to move your whole head to move floaters out of the way. I have significant floater issues but can move them around by moving just my eyes. Look right, then left (or the reverse) or down, then up (or the reverse) and let the floaters settle down in a new spot. Repeat as necessary. Usually works for me.

You must be logged in to post a comment.

Image of Mike McCabe

Mike McCabe

March 9, 2019 at 10:28 am

Hi Bob,
Great article! I've long been an enthusiast of daytime astronomical sightings and have thus far seen all the classical planets through a scope in the blue sky, and Venus and Jupiter naked eye in broad daylight, but not Sirius. One very fun thing I did do though was that I observed and photographed Sirius in the noon-time sky this past July, when Sirius wasn't quite in astronomical conjunction with the Sun but definitely in astrological conjunction, or perhaps in appulse. My curiosity got piqued when a guest at our July meeting asked if we were doing anything for the Heliacal Rising of Sopdet, which at first gave me pause but when we eventually figured out what she was talking about I wondered if I could "see" (obviously with optical aid) Sirius sooner than the heliacal rising. The answer was a definitive 'yes', and I enjoyed the heck out of that. I've got the pictures if you'd like.

You must be logged in to post a comment.

Image of Bob King

Bob King

March 11, 2019 at 5:06 pm

Hi Mike,
You photographed Sirius at noon? Amazing. Was that through a telescope or just straight with a camera and telephoto lens? Yes, please post a photo or send to me at: nightsky55@gmail.com Thanks!

You must be logged in to post a comment.

Image of Stub Mandrel

Stub Mandrel

March 9, 2019 at 4:57 pm

I want to try this!

4 or 5 years ago, I made a habit of spotting Jupiter very evening as I walked the dog, by knowing where to look and timing my walk just right I was able to spot it before sunset quite easily. It would always be invisible when setting out and usually obvious by the time I got home. It really was a case of getting my eye in, but I had a few points on the walk where I had landmarks. As I recall there was a period when both Venus and Jupiter were possible.

You must be logged in to post a comment.

Image of Bob King

Bob King

March 11, 2019 at 5:04 pm

Stub,
Once you gain that familiarity, everything gets easier.

You must be logged in to post a comment.

Image of SWN

SWN

March 12, 2019 at 11:10 am

Hello, Bob!
Thanks for the interesting article.
On October 10, 2013, I observed the Sirius with the unaided eye for 4 minutes after the sunrise. As a guide, I used a tree branch.
Latitude 49.7°

You must be logged in to post a comment.

Image of Bob King

Bob King

March 13, 2019 at 7:21 pm

You're welcome, SWN. And congratulations! I think we're tied for time.

You must be logged in to post a comment.

Image of Jakob

Jakob

March 18, 2019 at 2:18 pm

My first clear evening in three weeks and my first ever try spotting Sirius in daylight. Easy with my binos 5 min before sundown but I had no positive sighting without the help of my binoculars until 2 min after sunset . I will try again now knowing exactly where go look. Jakob

You must be logged in to post a comment.

Image of Markhl

Markhl

March 29, 2019 at 1:07 pm

I was able to see Sirius in the daytime at least 1 min before sunset. I was able to photograph it 1-8 min after sunset using a smartphone or a consumer-grade Canon SX120IS camera. I walked around to align Sirius with a distant tree or bush, to let the phone focus on a terrestrial object and on Sirius. Three attempts were made from California, near 34 degrees latitude. I expect the daytime-Sirius challenge to be easier at high altitude or in a canyon.

Cottonwood Canyon, March 16, found a few min before sunset with 7x35 binoculars and then with the eye. I took a photo 2 min after sunset using an iPhone X. Very clear, visibility tens of miles, about 3500 feet elevation, and in a canyon that reduced some scattered sunlight.

Borrego Springs, March 27. 18:53 saw with binoculars, 19:02 sunset, 19:03 photo using SX120IS camera, 19:04 seen with the eye, 19:10 photographed using iPhone X.

Irvine, March 28. Seen with binoculars then 19:07 with naked eye, 19:08 sunset, 19:13 photographed using SX120IS camera.

You must be logged in to post a comment.

You must be logged in to post a comment.