Telescope Buying Tips, the Moon Meets Jupiter, Mars Tickles the Beehive, and Venus Grazes Globulars!
The globular star cluster known as Messier 22 and the Great Sagittarius Cluster. Venus will shine near this object this week. The cluster spans about one-third of the full moon’s diameter and is visible in binoculars and backyard telescopes. The best time to view its rich, “sugar on black velvet” spectacle is during the summer months when it is above the southern horizon in evening. (Sloan DSS image)
Hello, Night Sky Aficionados!
Here are your Astronomy Skylights for the week of November 17th, 2024 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are expressed in Eastern Time. To subscribe to these emails please click this MailChimp link.
If you’d like me to bring my Digital Starlab portable inflatable planetarium to your school or other daytime or evening event in Simcoe, Grey, and Bruce Counties, or deliver a virtual session anywhere, contact me through AstroGeo.ca, and we’ll tour the Universe, or the Earth’s interior, together! My book with John A. Read entitled 110 Things to See With a Telescope is a guide to viewing the deep sky objects in the Messier List – for both beginners and seasoned astronomers. DM me to order a signed copy!
It’s time to think about investing in a telescope for all the planet-watching we’ll do this winter, so I share some tips and suggestions. The waning moon will gradually vacate the evening sky worldwide, but not before posing prettily with Jupiter. Meanwhile, Saturn will shine due south in evening and Mercury and Venus will shine after sunset, with Venus posing close to several globular star clusters. Read on for your Skylights!
Telescope Buying Tips
Quite a few people ask me about buying a first telescope, especially with all the planets available nowadays. Before you go about your shopping, consider these questions: What kinds of objects do I want to view? Does it need to be portable? Does it need to be kid-friendly? What’s my budget? Do I want to photograph the sky with the telescope – now, or eventually? A telescope store, or your friendly neighbourhood astronomer, will need the answers in order to suggest your best options.
For beginners, the most important things are ease of use, portability, and quality of the optics. Below I will highlight some telescopes that fit the bill, and mention some additional important considerations.
The aperture of a telescope, i.e., the diameter of its main mirror or lens, affects its performance, cost, and portability. You don’t need a large aperture telescope to see the moon and bright planets since they are inherently bright. Wider aperture telescopes gather more light, allowing fainter objects to be seen more easily – even from the suburbs. A larger aperture also increases the telescope’s angular resolution, or sharpness, which is especially helpful for planets.
In a refractor telescope (the type with the lens at the front end of the main tube), look for a minimum aperture of 80-mm, which will offer nice views of the planets, the moon, and double stars – as well as brighter nebulae, clusters, and brighter galaxies (such as the Andromeda Galaxy).
The light-gathering performance of a telescope improves with the square of the aperture, so an 80-mm telescope is (80*80)/(60*60) = 1.8 times more capable than the 60-mm telescopes you tend to find in department stores! That’s nearly double the light-gathering ability! Refractor telescopes are easy to carry around the yard, but they can be tricky to tuck into your car (unless the tube easily can be detached from the tripod). Expensive refractor telescopes use advanced glass that eliminates colour fringes around bright objects – so they are preferred by astro-imagers.
In reflector telescopes (the type with the large mirror inside the bottom of the main tube), apertures of 6 or 8 inches (150-mm to 200-mm) are common and affordable. Many entry-level models use 4.5-inch (115-mm) mirrors. Because of the aperture scaling rule, reflectors routinely outperform refractor telescopes without you needing to spend much more. They let you view dimmer galaxies and clusters while also showing the bright objects. (An 8-inch reflector gathers more than six times as much light as an 80-mm refractor!) Reflectors tend to be larger and heavier than refractors, affecting portability and storage.
Another important factor when shopping is the mount. Most refractor telescopes are mounted on a tripod. Sturdiness is essential. A high quality telescope on a rickety mount is practically useless. Every time you touch it, for focusing or while centring an object, you set off wild shaking of the image. This is one of the main reasons why cheap department store telescopes are poor investments – people get frustrated when they can’t put objects in the field of view and then keep them there.
The best mount for beginners is the altitude-azimuth or Alt-Az mount. They tilt the telescope up-down and swivel it left-right while the eyepiece stays in a convenient position. The better types have knobs that let you nudge the telescope while you are viewing, to keep objects from drifting out of sight due to the Earth’s rotation. Beginners should avoid buying telescopes on equatorial mounts. They are easily recognized by their tilted axes and the heavy counter-weight used to balance the weight of the telescope. Sure – they look more exotic, but they need to be balanced and polar aligned to work properly, and that takes some skill. The movements needed to centre targets will seem non-intuitive, and the eyepiece can up underneath the telescope!
The type of telescope I recommend most for beginners is the Dobsonian–mounted reflector. While larger and heavier than tripod telescopes, Dobsonians (or Dob’s) are extremely simple and easy to set up and to use. They are less portable, but are quite rugged, and can be transported in the trunk of your car if you pad them decently. That said, you can also buy smaller, tabletop Dobsonians that are easy for the kids to carry around.
The beauty of the Dobsonian design is the extremely sturdy mounting system – not a tripod, but a swivelling and tilting box that holds the telescope’s cannon-like tube. Once aimed at a target, a simple nudge with your finger will re-centre the object without any undue shaking. These types of telescopes typically show a generous amount of sky in the eyepiece, making finding targets much easier.
Advanced amateur astronomers often buy their telescope tube, mount, and accessories separately. Beginners prefer an all-in-one package that includes the telescope, mount, eyepiece(s), and finderscope. Below are a few recommended models for beginners and junior astronomers. While you might be tempted to spend only a little bit on a first telescope – you run the risk of buying a piece of junk made using plastic parts that break easily, is too rickety to use, or that simply doesn’t produce a sharp view. That could destroy any budding interest in the hobby. A better quality telescope will last a lifetime and can even be sold at a decent price. If you can’t afford to spend several hundred dollars for a decent telescope, consider purchasing a pair of good quality binoculars, instead. Those will work very well for youngsters, especially mounted on a tripod, and can be used for birding and sports, too. Local astronomy club star parties offer excellent opportunities to try out various types and ask the experts questions!
Here’s a 102-mm diameter refractor that ticks most the boxes in terms of price, optics, tripod, and accessories – the Sky-Watcher StarTravel 102 AZ3 refractor. It has a generous aperture and a lower focal ratio (f/4.9) that yields a wider view of the sky, making finding objects easier, and it has achromatic optics to reduce colour fringes from bright objects. It lists for CDN $540 and up from many vendors, including https://kwtelescope.com/startravel-102-az3/ in Waterloo, Ontario, https://khanscope.com/collections/sky-watcher-usa/products/sky-watcher-startravel-102-az3-telescope-s10100 in Toronto, and https://maisonastronomie.ca/product/f-refracteur-102-az3/ in Montréal, Québec. The telescope’s “AZ3” mount is a good, lightweight, and sturdy tripod that includes slow motion controls for following the object as the Earth turns. Sky-Watcher also sells a larger aperture version of this telescope. Any other brand with similar specifications should be okay, too. I suggest buying a 90° star diagonal to use in place of the included 45° erect image diagonal. (Your retailer can help with that.)
The StarTravel 102 telescope will not magnify the planets very much because of its smaller f/4.9 focal ratio. If the moon and planets are your primary interest, consider the Explore Scientific Firstlight Series telescopes, such as this 80-mm version from Ontario Telescope for $300 or their 102-mm version here for $420. The f/8 focal ratio will enlarge the planets nicely.
Here are some links for Dobsonian reflectors. A Sky-watcher Classic 150P 6” Dobsonian lists for CDN $530 at https://telescopescanada.ca/products/s11600?_pos=1&_sid=9fe5fa6e0&_ss=r. The 8” Dobsonian lists for CDN $740. Many retailers carry them. In the tabletop Dob family, the Orion Starblast 4.5 for $300 at https://maisonastronomie.ca/en/product/orion-starblast-4-5/ will suit beginners/kids well, or the Sky-Watcher Heritage 130 at https://kwtelescope.com/heritage-130-tabletop-dobsonian/ for $310.
While computerized telescopes are terrific, I advise beginners not to buy them until they’ve learned the major elements of the sky. GO-TO systems, as they are called, can slew to an object for you – but if you don’t know how to align them, and where to find the target in the sky in the first place, then how will you trouble-shoot them if you can’t see anything through the eyepiece? If you do want one, consider a Schmidt-Cassegrain Telescope (SCT) model. SCT’s combine lenses and mirrors into a smaller, stubbier tube, and are very portable, though a bit heavier. The Celestron Nexstar line of telescopes is available just about everywhere, including https://kwtelescope.com/nexstar-6se-sct/ The 6-inch diameter Celestron Nexstar 6se lists for CDN $1200. Note that you’ll need a continuous power system (12V battery pack or AC adapter) for any Go-to telescope system. An alternative to the computerized telescope is the Celestron StarSense Explorer line. Those use a smartphone holder and a mirror, mounted on a beginner telescope, to help you find sky objects – even dimmer, hard-to-find-from-the-driveway targets. They are available all over, including at Ontario Telescope. But they can be pricey.
The new kid on the block is the Seestar S50 robotic telescope from ZWO, which retails for about CDN $690. Instead of looking into an eyepiece, they send pictures or video of the object to your phone or tablet over Bluetooth or wifi. You can even control it while you stay warm inside! The Seestar S50 finds the objects for you and takes combine multiple exposures to brighten the fainter, harder-to-see objects. I purchased one this year. It’s easy to use and lots of fun. It’s got a rechargeable battery, includes the tripod and case, and even a solar filter to image sunspots! ZWO have recently announced the smaller, less expensive Seestar S30 model.
Some of the best southern Ontario telescope vendors include Ontario Telescope, KW Telescope, and Khan Scope. Across Canada, consider All-star Telescope in Edmonton and Mason de l’Astronomie in Montreal. If you live in the USA, try B&H Photo. While I have shared links to specific vendors above, the same models can usually be purchased from any of these vendors. Try to avoid buying inexpensive telescopes from big box stores. Remember that Amazon won’t provide the advice and the after-purchase support that a store can.
Many telescope vendors offer both new and used equipment, which can be a very cost effective solution. Used Dobsonians are common on sites like FaceBook marketplace and Kijiji, mainly because people find them hard to store or need to sell them when they move. Typical prices for good, used telescopes range from $250 to $600. If you are buying used, make sure that you try out the telescope on a star – to ensure that you can achieve a sharp pinpoint focus. (And use caution when engaging in cash transactions with strangers.)
One last tip – the eyepieces do the job of magnifying. So only consider telescopes that accept eyepieces with 1.25” or 2” diameter barrels – the standard for quality equipment. That way, you can add extra eyepieces, or upgrade to better quality ones later. You can mix brands as long as the barrel size matches your telescope. The useful range of magnification in a typical backyard telescope is 40x to 250x. If the sky conditions are very steady, you can push that to 300 to 400x. The “power” or “times, x” is calculated by dividing the telescope’s focal length by the eyepiece focal length, which is usually prominently labelled on the eyepiece.
Meteor Showers This Week
The Leonids meteor shower, which is derived from bits of material dropped when periodic Comet 55P/Tempel-Tuttle traverses the inner solar system every 33 years, runs from November 5 to December 2, annually. The peak of the shower, when up to 15 meteors per hour are common, was last night (Saturday) in the Americas. You should still see a few Leonids after dusk tonight (Sunday). Many Leonids have persistent trains and strong colour. I posted a nice photo of Leonids last week here, where I also talked about what meteor showers are and how best to see them.
Unfortunately, a bright moon will shine all night long during this year’s Leonids shower, obscuring the fainter meteors – but another good shower is coming!
The Moon
For the first part of this week, the recently-super moon will flood the early-evening sky with reflected sunlight. But for the coming weekend, its waning gibbous phase will rise and shine after midnight, leaving skywatchers worldwide with plenty of stars (and planets) to see after dinner.
Tonight (Sunday) in mid-evening, the bright, waning gibbous moon will shine in the eastern sky with brilliant Jupiter to its right, making a nice photo-op. The duo will cross the sky overnight. By sunrise on Monday, the moon will be farther from Jupiter and the diurnal rotation of the sky will lift the moon above Jupiter.
Every night the moon will rise about an hour later and wane in illuminated phase. The moon will spend Monday and Tuesday night in Gemini (the Twins), shining especially close to the bright stars Pollux and Castor on Tuesday. Watch for reddish Mars shining below them after it rises in late evening. On Wednesday night, the moon will shine several finger widths to the lower left (or celestial east) of Mars in Cancer (the Crab) – close enough for them to share the view in binoculars. Binoculars should also reveal a large collection of stars scattered below Mars – the open star cluster known as Messier 44 or the Beehive Cluster. To better see the “bees”, which cover an area more than twice the moon’s diameter, hide the moon out of sight beyond the left edge of your binoculars. The pale form of the moon will continue to be visible in the south and western sky until beyond noon.
The moon will spend the rest of this week visiting Leo (the Lion), but you’ll only be able to see it after midnight. The very bright star sparking near the moon on Friday and Saturday morning will be Regulus, a neighbour of our sun “only” 79 light-years away from us.
The moon will complete three quarters of its orbit around Earth, measured from the previous new moon, on Saturday, November 23 at 01:28 Greenwich Mean Time, which converts to Friday at 8:28 pm EST and 5:28 pm PST. At its third (or last) quarter phase, the moon is half-illuminated, on its western, sunward side. The week of dark, moonless skies that follow this phase are the best ones for observing fainter deep sky targets in evening.
The Planets
All of the planets will be continue to be visible in the evening and late-night sky for the next week or two, and then all of them except Mercury, will be around during the coming months – making your telescope investment pay off! Here’s where to look for them.
Mercury will continue to lurk just above the southwestern horizon for a short time after sunset. Its position 2 degrees below (or south of) the severely slanted evening ecliptic is keeping the planet too low in the sky for easy viewing from northerly latitudes, but if you live close to the tropics or in the Southern Hemisphere, Mercury has been putting on a fine and easy showing for you. Now it is starting to slide back towards the sun. In a telescope, Mercury will display a half-moon shape that grows a bit larger every day as its orbit brings it closer to Earth. The optimal viewing times at mid-northern latitudes will start around 5 pm local time. Don’t aim binoculars above the western horizon until after the sun has fully set.
You can use the brilliant, magnitude -4.1 planet Venus to help you find Mercury. (The more negative the magnitude value of a celestial object, the brighter it is!) Venus will catch your eye in the lower part of the southwestern sky even before the sun has set – though you might need to stand where trees or buildings don’t block your view of it. Mercury’s tint dot will be located about two fist diameters to Venus’ lower right (or celestial west).
Since Venus is completing a passage beyond the sun, it will increase its angle from the sun every day and move closer to Earth, causing it to slowly wane in illuminated phase and grow larger in telescopes. Venus will be safe to view through binoculars or a telescope after the sun has completely disappeared. Under magnification the planet will show a 72%-illuminated, football shape. Venus is now setting about 2.5 hours after sunset, so you have plenty of time to enjoy it. (If you see something bright that is moving left or right, or blinking, it’s an airplane.) The stars of Sagittarius (the Archer) around Venus will have appeared by the time Venus sets.
The eastward orbital motion of Venus is carrying it across the Milky Way, allowing imagers and telescope-owners telescopes to see the planet paired with several bright deep sky objects. Venus will shine to the left of the prominent globular star cluster Messier 28 and below Messier 22 aka the Great Sagittarius Cluster tonight (Sunday) and then climb to Messier 22’s left for several more days. The planet and the cluster will share the field of view of a low power eyepiece, but the cluster’s fuzzy patch will show better with bright Venus tucked just out of sight. At mid-northern latitudes, the sky will darken nicely before they set, but observers at southerly latitudes will get an even better view.
Once the sky is nearly dark on any evening, you can turn and face south to see the yellowish dot of Saturn shining not too high up in sky. You might also see the bright star Fomalhaut in the constellation of Piscis Austrinus (the Southern Fish) twinkling about two fist diameters below, and a little to the right, of Saturn.
Saturn and the faintish stars of Aquarius (the Water-Bearer) surrounding it will set the west around 12:45 am local time, but you’ll have clear views of the planet in any backyard telescope until about 10:30 pm. Sharp eyes and binoculars will show you a bent-line trio of stars collectively named Psi1,2,3 Aquarii sparkling a few finger widths to Saturn’s lower left, and two redder stars named Phi and Chi Aquarii to Saturn’s left and lower left, respectively. The entire group will fit in your binoculars’ field of view. An even brighter star named Hydor will appear a thumb’s width to Saturn’s upper right (or celestial WNW).
Saturn’s bright, but extremely thin rings effectively disappear when they become edge-on to Earth every 15 years. Since they will do that in late March, 2025, the rings already appear as a thick line drawn through the planet. Good binoculars can hint that Saturn has rings, but any size of telescope will show the rings and some of Saturn’s larger moons, too. In most years, Saturn’s moons are sprinkled around the planet, unlike Jupiter’s Galileans moons, which are always in a line. But while Earth is within months of being aligned with Saturn’s ring plane, its moons remain within a zone drawn through the rings.
Saturn’s largest and brightest moon Titan “TIE-tan” never wanders more than five times the width of Saturn’s rings from the planet. The much fainter moon named Iapetus “eye-YA-pet-us” can stray up to twelve times the ring width during its 80-day orbit of Saturn. The next brightest moons Rhea “REE-ya”, Dione “Dee-OWN-ee”, Tethys “Teth-EES”, Enceladus “En-SELL-a-dus”, and Mimas “MY-mass” all stay within one ring-width of Saturn. You may be surprised at how many of those six you can see through your telescope if you look closely when the sky is clear, dark, and calm.
During this week, Titan will start from off to Saturn’s left (or celestial east) tonight (Sunday), pass just below (celestial south of) Saturn on Wednesday, and then swing out to Saturn’s right (or celestial west) by next Sunday night. (Remember that your telescope will probably flip the view around.) The rest of the moons will be tiny specks in a line near the rings. Earth’s perspective of the Saturn system will also cause Saturn’s moons and their small black shadows to frequently cross its disk – but you’ll need a very high quality telescope to watch those.
The distant blue planet Neptune can be seen in a backyard telescope as it follows Saturn across the sky every night. During early evening, search for the slow-moving outer planet in the southern sky, just shy of 1.5 fist widths to the left (or celestial ENE) of Saturn and a palm’s width below the circle of faint stars that forms Pisces’ western fish. It will be easier to see while the moon is out of the sky later this week. Use binoculars to find the upright rectangle formed by the medium-bright stars 27, 29, 30, and 33 Piscium. Neptune will be the bluish, dull “star” sitting about two finger widths above (or 2° celestial north of) that box.
Uranus and Jupiter are over in the eastern evening sky. Just days past opposition and therefore peak visibility for this year, Uranus will just be clearing the trees as the sky gets dark enough to see its magnitude +5.6 speck. It will be positioned about a palm’s width to the right (or celestial southwest) of the bright little Pleiades star cluster in Taurus (the Bull). Uranus has been moving slowly retrograde westwards through western Taurus. If you use your binoculars to find the medium-bright stars named Botein and Epsilon Arietis, Uranus will be the dull-looking blue-green “star” located several finger widths below (or southeast of) them. To get you in the vicinity of Uranus, look for the bright star Menkar shining 2.2 fist diameters off to the right of the Pleiades. Uranus will be a quarter of the way along the line joining the bottom star of the Pleiades to Menkar.
Dazzling Jupiter will draw your attention in the east after it rises at around 6 pm local time. From now until early February, Jupiter will be creeping west between the horn stars of Taurus (the Bull). Named Elnath and Zeta Tauri, those stars will shine to Jupiter’s upper left and lower left, respectively. Jupiter’s westerly motion will also carry it closer to the bright, reddish star Aldebaran, which marks the eye of the bull. This week, Jupiter and Aldebaran will be almost a fist’s diameter apart, and closing. The name Aldebaran derives from the Arabic expression “al Dabarān” or “the Follower”, likely referring to the Pleiades cluster to its celestial west that it chases across the night sky.
Tonight (Sunday) the bright moon will gleam to Jupiter’s lower left in a nice photo op. The winter constellations will shine below Jupiter every day from late evening onward, and then become rotated to the planet’s left after midnight. Jupiter will reach its highest point in the sky, due south, during the wee hours and then blaze as it descends the western sky toward sunrise. Early risers will be able to see the especially bright star Sirius shining off to Jupiter’s left before dawn.
Any size of binoculars will show you Jupiter’s four Galilean moons named Io, Europa, Ganymede, and Callisto lined up beside the planet. Those moons complete orbits of the planet every 1.7, 3.6, 7.2, and 16.7 days, respectively. If you see fewer than four moons, then one or more of them is crossing in front of or behind Jupiter, or hiding in Jupiter’s dark shadow – or two of the moons are very close together, or one moon is eclipsing or occulting another one. All of the moons will gather to one side of the planet on Tuesday night.
Jupiter will continue to get a little brighter and a little larger until its opposition night in early December. Even a small, but decent quality telescope can show you Jupiter’s dark belts and light zones, which are aligned parallel to its equator. With a better grade of optics, Jupiter’s Great Red Spot, a cyclonic storm that has raged for hundreds of years, becomes visible for several hours when it crosses the planet every 2nd or 3rd night. For observers in the Americas, that GRS will cross Jupiter’s disk during early evening on Monday, Wednesday, and Saturday night, and also around midnight Eastern time tonight (Sunday), Tuesday, Friday, and next Sunday night. If you have any coloured filters or nebula filters for your telescope, try enhancing the spot with them.
From time to time, observers with good quality telescopes can watch the black shadows of the Galilean moons travel across Jupiter’s disk. In the Americas, Io’s little shadow will cross on Saturday morning, November 23 between 12:42 am and 2:50 am EST (or 05:42 to 07:50 GMT).
The prominent, reddish dot of Mars will clear the rooftops in the east by about 10:30 pm local time. Watch for the bright star Pollux, the lower of the “twin” stars of Gemini, shining about a fist’s diameter above Mars. The motion of the red planet through the faint stars of Cancer (the Crab) is slowing as it prepares to enter a retrograde loop at month’s end. As I mentioned above, you can use binoculars to see the scattered stars of the Beehive cluster sprinkled several finger widths below Mars on any night – not just when the moon crashes their party on Wednesday.
Early risers can easily see Mars shining high in the southwestern sky at sunrise to the upper left of Jupiter. The winter constellations will be arrayed between those two planets. In a telescope this week, the red planet will display a small, reddish disk without much detail, but that will change as Mars gets closer to Earth every day until its opposition night on January 15-16.
Public Astronomy-Themed Events
Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party – broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. They host in-person viewing on the first clear Wednesday night each month. Other Wednesdays they stream views online via the observatory YouTube channel. Details are here.
At 7:30 pm on Wednesday, November 20, the RASC Toronto Centre will livestream their free monthly Speaker’s Night Meeting. The speaker will be Claude Cournoyer-Cloutier, a PhD Candidate in Astrophysics at McMaster University. Her topic will be Stellar Siblings: Binary Stars and Star Clusters in the Milky Way and Beyond. Check here for details and watch the presentation at https://www.youtube.com/rasctoronto/live.
On Sunday afternoon, November 24 from 12:30 to 1:30 pm EDT, head to the David Dunlap Observatory for in-person DDO Sunday Sungazing. Safely observe the sun with RASC Toronto astronomers! During the session, which is for ages 7 and up, a DDO Astronomer will answer your questions about our closest star – the sun! Registrants will be given an eclipse viewer, learn how the sun works and how it affects our home planet, view the sun through solar telescopes, weather permitting. More information is here and the registration link is at ActiveRH.
Keep your eyes on the skies! I love getting questions and requests. Send me some!