What Does M4 REALLY Look Like Through a Telescope?

[00:00:08]Hello [music] and welcome to the program Sula's Big Adventures with me, Sula.

[00:00:13]Somebody on the channel suggested that I make a video about M4. So tonight we're taking a look at one of the finest globular clusters in the summer sky, Messier 4 or M4.

[00:00:26]It's located in the constellation Scorpius, the scorpion.

[00:00:30]M4 sits just over a degree west of the brilliant red star Antares, making it one of the easiest globular clusters to locate.

[00:00:40]It's located at a distance of only about 7200 light-years, so it's one of the closest globular clusters to Earth. M4 is estimated to be around 12 billion years old, and it contains well over 100,000 stars. Unlike many globular clusters, it isn't extremely condensed though, which means it begins resolving into individual stars even at relatively modest telescopes. One of its most distinctive features is a striking bar-like chain of brighter stars that runs through the center of the cluster.

[00:01:17]This unusual feature gives M4 a unique appearance and makes it easy to distinguish from other globular clusters once you've seen it.

[00:01:28]Let's take a look at how M4 appeared through each of the instruments that I used to observe it.

[00:01:37]In 12 by 50 binoculars, M4 is surprisingly easy to locate thanks to its proximity to Antares. Instead of individual stars, the cluster appears as a soft round patch of light with a slightly brighter center.

[00:01:56]It has a diffuse misty appearance that clearly sets it apart from nearby field stars.

[00:02:04]But there's no hint of resolution at that aperture.

[00:02:08]But it's a nice reminder that even a simple pair of binoculars can reveal distant globular clusters.

[00:02:18]Nice.

[00:02:20]Right now, I'm looking at M4 globular cluster in Scorpius.

[00:02:25]Very easy to find. I'm looking with a pair of 12 by 50 binoculars.

[00:02:30]You just go to Antares, the brightest star in Scorpius, the heart of the scorpion, >> [snorts] >> and you can fit it in the same field of view. If for some reason you can't see it, you should be able to, but it makes a triangle with um Sigma Scorpii.

[00:02:52]Shallow triangle.

[00:02:54]>> [snorts] >> But you should be able to fit it in the same field of view with Antares.

[00:03:04]It looks like a a hazy ball with these binoculars.

[00:03:12]Moving up to the 102 mm refractor, M4 begins to show its true nature. The cluster is noticeably larger and the outer regions take on a grainy texture as a handful of individual stars begin to resolve around the the edges.

[00:03:31]The center still appears as a soft glow, but the cluster already has a much richer appearance than it did in the 12 by 50 binoculars.

[00:03:42]And with careful observation and the right magnification, you may even begin to notice the faint suggestion of the central bar of stars that makes M4 so distinctive.

[00:04:00]Nice.

[00:04:02]Now I'm looking at M4 in 102 mm refractor. I'm only at 30 times magnification, but I can still resolve stars even at this low magnification.

[00:04:18]But let's magnify and see if I can make out that bar in this little telescope.

[00:04:27]Beautiful.

[00:04:31]Now I'm at 71 times magnification and I do see the bar.

[00:04:40]Still not the cluster is still not very big.

[00:04:48]And so it's not that distinct, but I can see it, but I want to make it even bigger.

[00:04:58]Okay.

[00:05:00]I put this 3.5 mm in that gives me 204 times.

[00:05:07]And it's not that sharp.

[00:05:11]And I don't have anything in between.

[00:05:16]Uh so I I can see the bar, but I can't make it as distinctive as I would like, but it looks pretty good.

[00:05:29]In the 8-in Meade Cassegrain, M4 becomes an impressive globular cluster.

[00:05:37]Dozens of stars are resolved across much of the cluster, while the core remains only partially unresolved.

[00:05:45]The famous central bar of brighter stars now becomes obvious.

[00:05:51]And it stretches diagonally across the heart of the cluster.

[00:05:56]It gives M4 a character unlike almost any other globular cluster.

[00:06:02]The combination of resolved stars and the softly glowing core and that distinctive central bar makes this an impressive object on summer evenings at that aperture.

[00:06:16]Okay.

[00:06:18]I am camping, so I have all my camping gear, my 10-in Dobsonian and my 102-mm refractor.

[00:06:28]Someone complained that it was too much of a jump to go from a 4-in to a 10-in, but I couldn't fit my Meade LX90 in the car, so I borrowed Pepper's 8-in Schmidt-Cassegrain.

[00:06:44]And I'm looking at M4 globular cluster in Scorpius and oh my heavens, it looks spectacular.

[00:06:53]Oh, wow. That is beautiful. I can see so many stars.

[00:06:59]I have it at 200 times magnification and it fills the field of view. It is just gorgeous.

[00:07:08]I can clearly see the bar and I can resolve so many stars. So pretty.

[00:07:17]The 10-in reflector takes stargazing at an ancient globular cluster to another level.

[00:07:24]The cluster is richly resolved nearly all the way into the core with countless tiny stars scattered across the field.

[00:07:33]The central bar of stars stands out beautifully, appearing almost like a backbone running through the cluster.

[00:07:44]Around it, delicate chains and arcs of stars weave outward into the surrounding halo.

[00:07:52]And the overall appearance is wonderfully three-dimensional.

[00:07:58]Instead of looking like a flat collection of stars, M4 has a real depth to it with brighter stars layered over a background of fainter members.

[00:08:10]It's now a standing sight in a larger aperture telescope.

[00:08:16]Oh my heavens, how pretty.

[00:08:21]Beautiful. Now I'm looking at M4, beautiful globular cluster in Scorpius in my 254 mm reflector.

[00:08:31]I'm at 70 times.

[00:08:33]I can easily see the bar across it and I can make out so many stars.

[00:08:41]Incredible detail, beautiful.

[00:08:45]Gorgeous globular cluster.

[00:08:48]Wow.

[00:08:51]M4 is one of those objects that rewards every increase in aperture.

[00:08:57]Binoculars will reveal the mysterious glow, a 4-in refractor begins to resolve the outer stars, an 8-in telescope clearly brings out the cluster's unique central bar, and a 10-in reflector transforms it into a rich swarm of ancient suns with remarkable depth and texture.

[00:09:20]If you've never observed M4, I highly recommend that you add it to your summer observing list.

[00:09:28]It's easy to find, it's beautiful in any telescope, and its distinctive central bar of stars gives it a personality that's all its own.

[00:09:38]Well, thanks for watching. I hope you enjoyed it. So long till next time. Dark skies forever. [music] Sula signing off.