Astro Advent 2022

Advent can be a wonderful way to count down to Christmas. Unistellar Ambassador John Pickering had the idea to post a new astronomical image, taken this year, each day as we count down to Christmas. While I've been playing along and posting images on both Twitter and on Mastodon, I thought I would put them all here as well. 

So here they are:

No caption on the image for this one. The faint line underneath the star at center is NASA's Artemis I spacecraft, photographed December 8, 2022.

My Astro Advent for December 15th was an asteroid occultation that I observed this month as asteroid 1264 Letaba passed in front of a star.

The star Vega

I'm on Mastodon

 Hey, I am on Mastodon now and this post is basically to confirm my identity there, so feel free to otherwise ignore this.

Mastodon

A Harvest of Planets

 In my last post (back in August!) I posted this image of Jupiter taken with my Unistellar eVscope. 

Jupiter, with a hint of the Great Red Spot (right)

It's not super great (and it was up-scaled from the original), but it was by far the best image of Jupiter I had ever taken with an eVscope. Of course, an eVscope wasn't designed with planets in mind. Instead, it is a wide-field telescope. That means that the telescope is great at capturing large objects like nebulae, but not for planets. 

 At least that was true until a few days ago when Unistellar released verson 2.2.0 of their app. The update is specifically to improve the telescope's ability to image planets. It does this (presumably) in the same way that many planetary imagers do, by capturing video, tossing out the bad frames that have been blurred by Earth's atmosphere and then keeping and stacking the best ones. I had looked in to doing this and it seemed to involve multiple software packages to handle the various steps and, frankly, it seemed like kind of a lot of work --so much so that I likely wasn't going to go down that road. The good news is now I don't have to, as the app now does it all for me and the results are stunning. 

Have a look. Here's how Jupiter looks without and then with the new app running:

Okay, that blink is pretty fast, so here's a still of how Jupiter looks with the new imaging:

Yes, the image doesn't compete with the greats like Damian Peach, but it is a vast improvement on what was possible before. Jupiter's Great Red Spot (GRS) was easily visible, along with its North and South Equatorial Belts. 

The GRS was so prominently displayed that I decided to shoot Jupiter every 5 minutes for an hour to see if I could capture Jupiter's fast rotation. Here's the result:

I aligned the images by hand (so the alignments aren't perfect), but the result makes me happy. Jupiter spins once in just about 10 hours, so one hour of Earth time nicely reveals its rotation. 

The resolution here is just barely good enough that shadows of Jupiter's four major moons should be visible when they land on Jupiter's cloud tops and as the moons themselves should be visible when they transit across the face of Jupiter.

Look just below the middle of the South Equatorial Belt. See the little white spot? That's likely Jupiter's moon Europa as it was passing in front of Jupiter.

This technique works on Mars and Saturn too. Of course, Mars and Saturn are smaller in apparent size than Jupiter is, so there's less detail to see, but again, the improvement is really stellar. Previously Mars was nothing more than a reddish-orange dot, with no detail visible at all. 

On the left is the view of Mars that was facing Earth as shown in the SkySafari app on the right is my image of Mars. It is still quite small (and enlarged here), but surface detail are clearly visible. I'm no Mars expert, but I believe that the dark area near the middle is Meridiani Planum. The Mars Opportunity rover landed there in 2004. I'll be back to capture other features of Mars soon while it is close to Earth.

Finally, here's Saturn:

Again, this isn't an award-winning image, but it is nice to be able to see details pop on these planets. The ability to show them greatly improves the use of the eVscope, especially as a tool for public outreach and that is a win for everybody.

Finding Himalia - 2022 Edition

Last year I decided to see if I could image Jupiter's Moon Himalia and I blogged about it right here. I ended that blog post by saying that I would try to find it again in 2022. Well, it is 2022 and the time is right, but fading fast.

At magnitude 14.6 Himalia is not especially faint. Targets of that brightness are easy to catch with a Unistellar eVscope. The problem is that it is close to Jupiter in the sky and that Jupiter 17.4 magnitudes brighter than this moon! That means that Jupiter is more than nine million times brighter than Himalia!

To diminish the glare from Jupiter it is best to observe Himalia when our view of its orbit is such that it is both far from Jupiter and when Jupiter is close to Earth, which makes the moon's orbit look larger in the sky. Currently Himala's orbit is about 2 degrees across (4x the diameter of the full Moon).

Himalia's orbit around Jupiter (image from SkySafari Pro).

The peak of both these factors is right now (actually, it was just over a week ago) placing Himalia around 53 arc minutes (almost 1 degree) from Jupiter in the sky.

This year I was observing with an eVscope2. I also had an Optolong L-Pro filter on the telescope which I was hoping might diminish some of Jupiter's intense glare.

I looked for this little moon on August 26 & 27 2022. Thankfully, the glare from Jupiter did not look as bad as it did last when I tried this last year (I think that the filter helped), but the glare still makes the view different from one image to the next. Here are the two frames blinked:

Yeah, spotting it here is difficult, but you might notice that there is a galaxy (NGC 132) to the right of center. Himalia is beneath it in one frame (taken August 26) and to the right of it in the next. 

It is much easier to see in this view that has been cropped, zoomed and annotated:

A nice clean detection!

It turns out that Jupiter's moon Elara was likely in the same field of view of my full-frame images, but at magnitude 16.2 it is quite a bit fainter and I'm not convinced that I caught it. 

While I was pointed near Jupiter I decided to go ahead and look at Jupiter too and was pleased to see that the Great Red Spot was visible. Now the eVscope2 has a really wide field of view and Jupiter looks pretty tiny, but with cropping and upscalling you can easily see its belts, zones and even the Great Red Spot.

Jupiter with the Great Red Spot

I've got some other faint moons to try. I will report back here if I have any success.

 

The Cluster and the Comet

Back in June I posted about observing comets (see it here) and even mentioned the one that is currently closest to Earth which has this beautiful name: C/2017 K2 PanSTARRS. 

Comets have different parts to their names. The C means that is is a non-periodic comet. Once it makes this pass through the inner Solar System it is never coming back. 2017 was the year of its discovery and the K2 means that it was the 2nd comet discovered in the 2nd half of May. Comets also get the name of their discoverer. In this case that wasn't a person, but rather the Panoramic Survey Telescope & Rapid Response System, aka PanSTARRS. 

The image below shows the comet's orbit through the inner Solar System. 

It doesn't get especially close to Earth. It was at its closest a few days ago when it was 1.8 astronomical units (166 million miles) from Earth. Interestingly enough when the comet was closest to Earth it was also  nearly in the same direction in the sky as the globular star cluster Messier 10. I managed to catch them with my Unistellar eVscope 2 on July 15th.

While the cluster and the comet appear to be next to each other, they are merely in the same direction. M10 is more than 14,000 light years from Earth, but when I took this image the comet was just 15 light minutes away. That's not close at all.

Observing the Sun with an eVscope

UPDATE: This blog post is now out of date, to see the newest information have a look at my Here Comes the Sun post.

This is a good time to observe our nearest star, the Sun. The last several years the Sun hasn't had many sunspots, but there have been plenty of them recently, making the view more interesting.

Observing the Sun with a telescope should only be done with the use of a solar filter that fits over the front end of the telescope.

I use a solar filter from Thousand Oaks Optical (SolarLite 5.75-inch) for my Unistellar eVscope 2. The Sun fits nicely within its field of view. Alas, the field of view is a bit too small for the whole Sun to be seen in an eVscope 1 or eQuinox.

Pointing the telescope at the Sun isn't too difficult. The key is to look at the telescope's shadow. 

When the shadow is smallest the telescope is pointed at the Sun. 

Focusing isn't easy. You can't use the Bahtinov mask. Instead, look very closely at some sunspots or even the edge of the Sun and carefully adjust your focus. It is usually best to take several images with slightly different adjustments and pick your best one. 

Most solar filters impart some color to the view of the Sun which is white in color (yes, many people refer to the Sun as a yellow star, but trust me, it's white). The combination of the Thousand Oaks filter with the fact that the eVscope is sensitive to near infrared light gives the Sun a color that isn't too pleasing to me (or very Sun-like):

This is easily fixed by simply converting the image to grayscale. I also usually do some very simple post-processing (on my phone!) to improve the sharpness and contrast of the image. 

When an eVscope is used to observe the Sun, it will not track on it, so you'll need to periodically move it to keep the Sun centered in view. This is very easy to do in version 2.0 of the Unistellar app.

Other than watching sunspots come and go, what can you do by observing them? I recently photographed the Sun seven days in a row to produce this short animation showing the Sun's rotation:

I cropped, aligned and rotated my images in Photoshop so that I could create this sequence.

The Sun takes about 27 days to make a full rotation, but it isn't a solid body, which means that its rotation period is different at its equator than it is at its poles. As the Sun spins this differential rotation helps to twist and warp its magnetic fields. When these magnetic fields break the Sun's surface (called the photosphere) they partially block the flow of heat from the Sun's interior giving rise to sunspots.

The immensity of the Sun is beyond the human experience. To give you a sense of perspective, let's look at one frame from the sequence above:

Do you see the blue dot that I added? That's the size of Earth compared to the Sun. Yes, the Sun is huge. 109 Earths could fit across its diameter.

The Sun is the source of the energy that powers life on Earth. As Earth orbits around the Sun we get different amounts of sunlight due to the fact that Earth's axis is tilted. When, as we are now, the Northern Hemisphere is tilted toward the Sun we get more daylight and that daylight is more intense. This gives us summer. At the same time those in the Southern Hemisphere are experiencing winter. It is this tilt that creates our seasons. 

Most people mistakenly assume that the seasons are caused by Earth's distance from the Sun. Earth's orbit is ever so slightly elliptical, meaning that our distance from the Sun does indeed change, but it isn't a big change. Surprising to most people is that fact that we are closest to the Sun in January during winter in the Northern Hemisphere. This does mean that the apparent size of the Sun in our sky changes from early January when we are closest to the Sun to early July when we are farthest from it. 

You would never notice this distance with your eyes (you shouldn't look directly at the Sun anyway), but it is clearly visible with a telescope:

I am sure that I'll come up with some other solar observing projects in the future, but that's it for now.

Go Long!

Nebulae, star clusters and galaxies are always popular targets in astronomy, but I sometimes like to go long and take a deeper look into the universe. The most distant objects that are consistently visible are quasars. For those who don't know, quasars are infant galaxies that have supermassive black holes in their cores. Black holes, as you might expect, are black, but when they have things like stars and gas clouds falling into them everything around the black hole gets super hot and shines with intense brightness allowing them to be seen from billions of light years away. 

When quasars were first found they were quite mysterious. They looked very much like stars in our own galaxy that were emitting radio waves. Nobody understood what they really were for quite sometime, but the first piece of the mystery to be solved was that they are immensely far away and therefore shining with a brightness that at the time could not be explained. The first quasar to have its distance identified was 3C 273 [Note: Quasars have terrible names!].

Quasar 3C 273

Determining the distance to a quasar is a matter of taking its spectrum to determine its redshift. From there getting the distance of the quasar is pretty straight forward if you understand exactly how the universe itself is expanding. There is still some disagreement as to the exact rate at which the universe is expanding, so the distances that I'll use here are not precise. 3C 273 lies some 2 billion light years from our home galaxy the Milky Way which, because that's how long its light took to get here, means that we see this core of a baby galaxy the way it looked 2 billion years ago.

It's important to put that figure into perspective. The light captured here with my 4.5-inch eVScope left that quasar 2 billion years ago. That was right around the same time that primitive, single-celled life was starting to seriously add oxygen into Earth's atmosphere [this was actually quite terrible for most things that were alive at the time, but that's another story].

The quasar known as PG 1427+480 [See, I told you they had terrible names, though most of them are a nod to their coordinates in the sky.] is marked in the image below:

PG 1427+480 is even farther away, with a distance 2.8 billion light years.  

Hopefully you haven't gotten tired of seeing dots yet. This next one is HS 0624+6907:

HS 0624+6907 is around 4.2 billion light years away. Light from this quasar left it when Earth was very young, around 500 million years before life began here.

The last one in this post is faint, so I've cropped the image from the full frame:

That little dot is a quasar known as S5 0014+81. The image shows light that left the quasar 11.96 billion years ago. Think about that. The light recorded here left the quasar long before Earth itself was formed.  Seeing this can really give you a sense of perspective. 

To find these quasars I rely heavily on the SkySafari Pro app, especially to identify the star fields. There's also a couple of sites on the Web that are helpful. The Frankfurt Quasar Monitoring site is a great resource and there's a text list of over 450 quasars here. There are various Cosmology Calculators online where you can input an object's redshift (z) and get a distance. You can find one here and here.

The Omega Glory

No, this isn't a post about the terrible Star Trek episode with the same name (I haven't blogged about Star Trek for quite some time now), but rather about the amazing globular star cluster known as Omega Centauri.

Last summer I blogged about the Globular Star Clusters of the Messier Catalog. In the post I mentioned that Omega Centauri is located too far south in the sky for Charles Messier to have seen it. The cluster barely makes it into the sky from my home, climbing just 9 degrees above the horizon. (I live at 33 degrees North, for anyone living further north, the cluster is even lower in the sky or not visible at all). Unfortunately a rather large hill completely blocks its view for me. 

Thankfully, I attended a star party in late April that had an unobstructed view of the southern sky and I was able to see this fine star cluster for the first time in years. It was also the first time I was able to catch it using my Unistellar eVscope2 and the view was impressive.

2-minute exposure of Omega Centauri

The cluster is amazing in every way. From dark skies it is visible without the use of optical aid from binoculars or a telescope. The cluster is 4 million times more massive than our Sun, making it the most massive of our Milky Way galaxy's globular star clusters. At its core the stars are so closely packed together that they are estimated to be just one tenth of a light year apart. Keep in mind that the closest star to our own Solar System is over 4 light years away. Imagine what the night sky would look like from a planet orbiting one of the stars within this cluster.

Omega Centauri may very well be the remnant of a smaller satellite galaxy that has been caught and disrupted by the Milky Way.

To put things into perspective compare the view above with that of another globular star cluster, Messier 13 the "great globular cluster in Hercules": 

This image of M13 was also taken with my eVscope, but when the cluster was high in the sky and with an exposure that was 10 times longer (20 minutes, instead of 2)! Don't get me wrong, M13 is a nice cluster, but it's not really "great" when compared to Omega Centauri. 

Why? Not only is Omega Centauri much more massive than M13 (M13 is only 500,000 times the mass of the Sun), but it is also closer to us. M13 is located around 22,000 light years from Earth, while Omega Centauri is 17,000. This closer distance and much greater number of stars make combine to make Omega Centauri truly glorious.