Celebrate the Start of Global Astronomy Month with an Online Messier Marathon

It’s the challenge for many a backyard observer: the Messier Marathon! And as we told you last week, with the passage of the spring equinox on March 20th means Messier Marathon season is now open. (See our article from David Dickinson with complete tips, tricks and optimal dates). But if you are hesitant to try this observing feat on your own or would rather participate from the comfort of your home, Gianluca Masi from the Virtual Telescope Project has an event just for you: an online Messier Marathon.

This will be the 6th year that the Virtual Telescope Project has on an online Messier Marathon, and they’ll be using their robotic telescopes, providing real time images — all while chatting and sharing the passion and excitement with people from around the world.

It starts on April 1, at 18.00 Universal Time. This is the perfect way to start Global Astronomy Month 2014, which is held in April every year and is the world’s largest global celebration of astronomy. Click here to join in the Marathon.

Ready, Set, Messier Marathon: A 2014 Guide

Have YOU seen all 110?

The passage of the northward equinox last week on March 20th means one thing in the minds of many a backyard observer: the start of Messier Marathon season. This is a time of year during which a dedicated observer can conceivably spot all of the objects in Charles Messier’s famous deep sky catalog in the span of one night.

We’ve written about some tips and tricks to completing this challenge previously, as well as the optimal dates for carrying a marathon out. Typically, the New Moon weekend nearest the March equinox is the best time of year for northern hemisphere observers to target all of the objects on Messier’s list. This works because a majority of the Messier objects are clustered into two regions: towards the core of our galaxy in Sagittarius — where the Sun sits during the December solstice — up through the summer triangle constellations of Cygnus, Aquila and Lyra, and in the bowl of Virgo asterism and its super cluster of galaxies that extends northward into the constellation of Coma Berenices. In March through early April the Sun sits in the constellation of Pisces, well away from the galactic plane.

The prospects for completing a Messier marathon in 2014 favor the last weekend on March on the 29th-30th. The Moon reaches New on Sunday, March 30th at 18:45 Universal Time/2:45 PM EDT.

Messier marathons first came into vogue in the early 1970s right around the time Schmidt-Cassegrain and large Dobsonian “light bucket” telescopes came into general use.

Charles Messier began noting the curious objects that he would later incorporate into his famous catalog during the summer of 1758, with his description of the Crab Nebula in Taurus, which would become Messier object number one or M1. Messier was a prolific comet hunter and discovered 21 comets in his lifetime. The catalog was compiled over the span of 13 years from 1771 to 1784. Messier’s original list contained 45 objects, and was later expanded in subsequent editions 103, with Messier’s assistant Pierre Méchain adding six more objects to the catalog. The list is generally tallied at 110 objects, with one famous controversy being M102, which is generally cited as a re-observation of M101 or the galaxy NGC 5866.

The catalog itself contains a grab bag of open and globular clusters, galaxies, planetary and diffuse nebulae, and one double star (M40). The Messier catalog spans the sky down to M7, an object also known as the Ptolemy Cluster, which is the southernmost object on the list at latitude -34 degrees 48’ south.

The first page of Messier's third revision of his catalog describing M1 through M5. Image in th Public Domain.
The first page of Messier’s third revision of his catalog, describing M1 through M5. Image in the Public Domain.

Messier observed from Paris at latitude +48 degrees 51’ north using two primary telescopes of the almost one dozen that he owned for his discoveries: a 6.4” Gregorian reflector and a 3.5” refractor. Messier knew nothing of the nature of these “faint fuzzies” that he’d periodically stumbled across in his cometary vigil. His original intent was to compile a list of “comet imposters” in the night sky for comet hunters to be aware of in their quests. In his words:

“What made me produce this catalog was the nebula which I had seen in Taurus while I was observing the comet of that year (1758). The shape and brightness of that nebula reminded me so much of a comet, that I undertook to find more of its kind, to save astronomers from confusing these nebulae with comets.”

“Beware, here doth not lie comets,” Messier admonishes future generations of observers. Still, some peculiarities remain in the catalog: why did Messier, for example, include such obvious “non-comets” as the Pleiades (M45), but skip over the brilliant Double Cluster in Perseus?

Charles Messier's 1771 sketch of the Orion nebula, M42 in the Messier Catalog. Image in the public domain.
Charles Messier’s 1771 sketch of the Orion nebula, M42 in the Messier Catalog. Image in the public domain.

Alas, such mysteries are known only to Messier, who was interred at the famous Père Lachaise cemetery after his death in 1817. When we visit Paris, we’ll bypass Jim Morison to leave a copy of Burnham’s Celestial Handbook at Messier’s grave.

And just like the road variety, “running the Messier marathon” takes all of the stamina and pacing that a visual athlete can muster. You’ll want to grab M77 and M74 immediately after dusk, or the marathon will be over before it starts. From there, move on up north to the famous Andromeda galaxy (M31) and the scattering of objects around it before settling in for a more leisurely observing pace moving westward through the constellations of Orion, Leo and surrounding objects.

An all-sky map showing the distribution of Messier objects. (Click to enlarge). Credit: Jim Cornmell under a Wikimedia Commons Attribution-Share Alike 3.0 Unported license.
An all-sky map showing the distribution of Messier objects. (Click to enlarge). Credit: Jim Cornmell under a Wikimedia Commons Attribution-Share Alike 3.0 Unported license.

Now towards the approach of local midnight comes the first large group: the Virgo cluster of galaxies extending through Coma Berenices, rising to the east. After this batch, you can catch some quick shut-eye before bagging the Messier objects towards the galactic center and up through Cygnus in the pre-dawn. Plan ahead; M52, M2 and M30 are especially notoriously difficult in the spring dawn sky!

It’s also worth noting your “attitude versus latitude” plays a role as well. To this end, Ed Kotapish compiled this nifty perpetual chart of when the entire Messier catalog is visible from respective latitudes:

A chart calculating number of total Messier objects that are visible on the dates (vertical column in month-day format) versus north latitude (top row). Note that this chart is pertpetual for non-leap years, and does not take into account the pahse of the Moon. Click to enlarge. Credit: Edward Kotapish.
A chart calculating number of total Messier objects that are visible on the dates (vertical column in month-day format) versus north latitude (top row). Note that this chart is pertpetual for non-leap years, and does not take into account the pahse of the Moon. Click to enlarge. Credit: Edward Kotapish.

“The bounds of the chart are for a variety of objects,” Ed told Universe Today. “I used nautical twilight (when the Sun falls below -12 degrees in elevation) as the starting and ending condition.” Ed also notes that the top curve of the chart on the morning side is bounded by the difficulty in finding troublesome M30, while the left bottom evening boundary is limited by the observability of M110 and M74, which can be a problem for observers at higher latitudes.

Alternate versions of the Messier marathon exist as well, such as imaging or even sketching all 110 objects in one night.

Why complete a Messier marathon? Well, not only does such a feat hone your visual skills as an observer, but it also familiarizes you with the entire catalog… and there’s nothing that says you have to complete it all in one evening, except of course, for bragging rights at the next star party!

Good luck!

-Here’s a handy list of all 110 of the Messier objects in the catalog.

-Be sure to send those pics of Messier objects and more in to Universe Today’s Flickr forum!

Join in an Online Messier Marathon

Have you ever done a Messier Marathon? Want to try it online from the comfort of your own home? Astrophysicist Gianluca Masi will host a webcast today (April 9, 2013) at 18:00 UTC (2 pm EDT) (update: this webcast has been postponed due to clouds. We’ll post the new date and time when it becomes available). You can join in at this link, and explore the many treasures of the famous Messier Catalog. Masi said they will try to see as many of 110 objects in the Messier Catalog as possible in a single viewing session. This is what is called a Messier Marathon!

This is the fifth time the Virutal Telescope Project has attempted this, and they’ve had great success previously. Masi is doing the Marathon their robotic telescopes, and will provide real time images and live comments, along with answering your questions and “sharing your passion and excitement with friends from all around the world.”

For more information on how to join in see the Virtual Telescope Project’s website. For more info on a Messier Marathon and how to do one, see our excellent recent post by David Dickinson.

Here’s some examples of what you will be seeing today during the webcast:

Why This Weekend is Perfect for a Messier Marathon

This coming weekend presents the first window for 2013 to complete a challenge in the realm of backyard astronomy and visual athletics. With some careful planning, persistence, and just plain luck, you can join the vaunted ranks of those seasoned observers who’ve seen all 110 objects in the Messier catalog… in one night.

Observing all of the objects in Messier’s catalog in a single night has become a bit of a sport over the last few decades for northern hemisphere observers, and several clubs and organizations now offer certificates for the same.  The catalog itself was a first attempt by French astronomer Charles Messier to catalog the menagerie of “faint fuzzies” strewn about the northern hemisphere sky.

Not that Charles knew much about the nature of what he was seeing. The modern Messier catalog includes a grab bag collection of galaxies, nebulae, open and globular clusters and more down to magnitude +11.5, all above declination -35°. Charles carried out his observations from Paris France at latitude +49° north. Unfortunately, this  also means that Messier catalog is the product of Charles Messier’s northern-based vantage point. The northernmost objects in the catalog are Messiers 81 & 82 at declination +69°, which never get above the horizon for observers south of latitude -21°. His initial publication of the catalog in 1774 contained 45 objects, and his final publication contained 103, with more objects added based on his notes after his death in 1817. (Fun fact: Messier is buried in the famous Père Lachaise Cemetery in Paris, site of other notable graves such as those of Chopin and Jim Morrison).

M51, the Whirlpool Galaxy, one of the more photogenic objects in the Messier catalog. (Credit: NASA/Hubble Heritage Project).
M51, the Whirlpool Galaxy, one of the more photogenic objects in the Messier catalog. (Credit: NASA/Hubble Heritage Project).

There’s a fair amount of controversy on Messier’s motivations and methods for compiling his catalog. The standard mantra that will probably always be with us is that Messier was frustrated with stumbling across these objects in his hunt for comets and decided to catalog them once and for all. He eventually discovered 13 comets in his lifetime, including Comet Lexell which passed only 2.2 million kilometres from Earth in 1770.

No one is certain where the modern tradition of the Messier Marathon arose, though it most likely had its roots in the amateur astronomy boom of the 1970s and was a fixture of many astronomy clubs by the 1980s. There are no Messier objects located between right ascension 21 hours 40 minutes  and 23 hours 20 minutes, and only one (M52)  between 23 hours 20 minutes and 0 hours 40 minutes. With the Sun reaching the “0 hour” equinoctial point on the March Vernal Equinox (falling on March 20th as reckoned in Universal Time for the next decade), all of the Messier objects are theoretically observable in one night around early March to early April. Taking into account for the New Moon nearest to the March equinox, the best dates for a weekend Messier marathon for the remainder of the decade are as follows;

Optimal Messier marathon dates for the remainder of the decade. (Compiled by author).
Optimal Messier marathon dates for the remainder of the decade. (Compiled by author).

Note that this year’s weekend is very nearly the earliest that it can occur. The optimal latitude for Messier marathoning is usually quoted as 25° north, about the latitude of Miami. It’s worth noting that 2013 is one of the very few years where the primary weekend falls on or before our shift one hour forward to Daylight Saving time, occurring this year on March 10th for North America.

Students of the Messier catalog will also know of the several controversies that exist within the list. For example, one wide double star in Ursa Major made its way into the catalog as Messier 40. There’s also been debate over the years as to the true identity of Messier 102, and most marathoners accept the galaxy NGC 5866 in its stead. Optics of the day weren’t the most stellar (bad pun intended) and this is evident in the inclusion of some objects but the omission of others. For example, it’s hard to imagine a would-be comet hunter mistaking the Pleiades (M45) for an icy interloper, but curiously, Messier omits the brilliant Double Cluster in Perseus.

M42, the Orion Nebula. (Photo by Author, taken back in the days of ye ole film!)
M42, the Orion Nebula. (Photo by Author, taken back in the days of ye ole film!)

It’s vital for Messier marathoners to run through objects in proper sequence. Most visual observers run these in groups, although Alex McConahay suggests in a recent April 2013 Sky & Telescope article that folks running a photographic marathon (see below) beware of wasting precious time crossing the celestial meridian (a maneuver which requires a telescope equipped with a German Equatorial mount to “flip” sides) hunting down objects. The unspoken “code of the skies” for visual Messier marathoners is that “Go-To” equipped scopes are forbidden. Part of the intended purpose of the exercise is to acquaint you with the night sky via star hopping to the target.

Most observers complete Messier objects in groups. You’ll want to nab M77 and M74 immediately after local dusk, or the marathon will be over before it starts. You’ll then want to move over to the Andromeda Galaxy and the collection of objects in its vicinity before scouring Orion and environs. From that point out, you can begin to slow down a bit and pace yourself through the galaxy groups in Coma Berenices and the Bowl of Virgo asterism. Another cluster of objects stretch out in the sky past midnight along the plane of our Milky Way Galaxy from Sagittarius to Cygnus, and the final (and often most troublesome) targets to bag are the Messier objects in Aquarius and M30 in Capricornus just before dawn. Remember, dark skies, warm clothes, and hot coffee are your friends in this endeavor!

There have been alternate rules or versions of Messier marathons over the years. Some imagers complete one-night photographic messier marathons. There are even abbreviated or expanded versions of the feat. It is also possible to nab most of the Messier catalog with a good pair of binoculars under clear skies. Probably the most challenging version we’ve heard of is sketching all 110 Messier objects in one evening… you might be forgiven for using a Go-To enabled telescope to accomplish this!

Finally, just like running marathons, the question we often get is why. Some may eschew transforming the art of dark sky observing into a task of visual gymnastics. We feel that to run through this most famous of catalogs in an evening is a great way to learn the sky and practice the fast-disappearing art of star hopping. And hey, no one’s saying you can’t take a year or three to finish the Messier catalog… its a big universe, and the New General Catalog (NGC) and Index Catalog (IC) containing thousands of objects will still be waiting. Have YOU seen all 110?

–      A perpetual listing of Messier marathon visibility by latitude by Tom Polakis.

–      An All Sky Map of the Messier catalog.

–      A handy priority list for a Messier marathon compiled by Don Machholz.

Weekly SkyWatcher’s Forecast – March 19-25, 2012

[/caption]

Greetings, fellow SkyWatchers! The week starts off with new Moon and the perfect opportunity to do a Messier Marathon. The planets continue to dazzle as we not only celebrate the Vernal Equinox, but the March Geminid meteor shower as well! If that doesn’t get your pulsar racing – nothing will. It’s time to get out your binoculars and telescopes and meet me in the backyard!

Monday, March 19 – Right now the Moon is between the Earth and the Sun, and you know what that means…New Moon! Tonight we’ll start in northern Puppis and collect three more Herschel studies as we begin at Alpha Monoceros and drop about four fingerwidths southeast to 19 Puppis.

NGC 2539 (Right Ascension: 8 : 10.7 – Declination: -12 : 50) averages around 6th magnitude and is a great catch for binoculars as an elongated hazy patch with 19 Puppis on the south side. Telescopes will begin resolution on its 65 compressed members, as well as split 19 Puppis – a wide triple. Shift about 5 degrees southwest and you find NGC 2479 (Right Ascension: 7 : 55.1 – Declination: -17 : 43) directly between two finderscope stars. At magnitude 9.6 it is telescopic only and will show as a smallish area of faint stars at low power. Head another degree or so southeast and you’ll encounter NGC 2509 (Right Ascension: 8 : 00.7 – Declination: -19 : 04) – a fairly large collection of around 40 stars that can be spotted in binoculars and small telescopes.

Tuesday, March 20 – Today is Vernal Equinox, one of the two times of the year that day and night become equal in length. From this point forward, the days will become longer – and our astronomy nights shorter! To the ancients, this was a time a renewal and planting – led by the goddess Eostre. As legend has it, she saved a bird whose wings were frozen from the winter’s cold, turning it into a hare which could also lay eggs. What a way to usher in the northern spring!

With the Moon still out of the picture, let’s finish our study of the Herschel objects in Puppis. Only three remain, and we’ll begin by dropping south-southeast of Rho and center the finder on a small collection of stars to locate NGC 2489 (Right Ascension: 7 : 56.2 – Declination: -30 : 04). At magnitude 7, this bright collection is worthy of binoculars, but only the small patch of stars in the center is the cluster. Under aperture and magnification you’ll find it to be a loose collection of around two dozen stars formed in interesting chains.

The next are a north-south oriented pair around 4 degrees due east of NGC 2489. You’ll find the northernmost – NGC 2571 (Right Ascension: 8 : 18.9 – Declination: -29 : 44) – at the northeast corner of a small finderscope or binocular triangle of faint stars. At magnitude 7, it will show as a fairly bright hazy spot with a few stars beginning to resolve with around 30 mixed magnitude members revealed to aperture. Less than a degree south is NGC 2567 (Right Ascension: 8 : 18.6 – Declination: -30 : 38). At around a half magnitude less in brightness, this rich open cluster has around 50 members to offer the larger telescope, which are arranged in loops and chains.

Congratulations on completing these challenging objects!

Are you up for another challenge? Then test your ability to judge magnitude as Mars has now dimmed to approximately -1.0. Does it look slightly different in size and brightness than it did a week or so ago? Keep watching!

Wednesday, March 21 – Take your telescopes or binoculars out tonight to look just north of Xi Puppis for a celebration of starlight known as M93 (Right Ascension: 7 : 44.6 – Declination: -23 : 52). Discovered in March of 1781 by Charles Messier, this bright open cluster is a rich concentration of various magnitudes that will simply explode in sprays of stellar fireworks in the eyepiece of a large telescope. Spanning 18 light-years of space and residing more than 3400 light-years away, it contains not only blue giants, but lovely golds as well. Jewels in the night…

Thursday, March 22 – Today in 1799 Friedrich Argelander was born. He was a compiler of star catalogues, studied variable stars and created the first international astronomical organization.

Tonight let’s celebrate no Moon and have a look at an object from an alternative catalog that was written by Lacaille, and which is about two fingerwidths south of Eta Canis Majoris.

Also known as Collinder 140, Lacaille’s 1751 catalog II.2 “nebulous star cluster” is a real beauty for binoculars and very low power in telescopes. More than 50% larger than the Full Moon, it contains around 30 stars and may be as far as 1000 light-years away. When re-cataloged by Collinder in 1931, its age was determined to be around 22 million years. While Lacaille noted it as nebulous, he was using a 15mm aperture reflector, and it is doubtful that he was able to fully resolve this splendid object. For telescope users, be sure to look for easy double Dunlop 47 in the same field.

Now, kick back and enjoy a spring evening with two meteor showers. In the northern hemisphere, look for the Camelopardalids. They have no definite peak, and a screaming fall rate of only one per hour. While that’s not much, at least they are the slowest meteors – entering our atmosphere at speeds of only 7 kilometers per second!

Far more interesting to both hemispheres will be the March Geminids which peak tonight. They were first discovered and recorded in 1973 and then confirmed in 1975. With a much faster fall rate of about 40 per hour, these slower than normal meteors will be fun to watch! When you see a bright streak, trace it back to its point of origin. Did you see a Camelopardalid, or a March Geminid?

Friday, March 23 – Today in 1840, the first photograph of the Moon was taken. The daguerreotype was exposed by American astronomer and medical doctor J. W. Draper. Draper’s fascination with chemical responses to light also led him to another first – a photo of the Orion Nebula.

Our target for tonight is an object that’s better suited for southern declinations – NGC 2451 (Right Ascension: 7 : 45.4 – Declination: -37 : 58). As both a Caldwell object (Collinder 161) and a southern skies binocular challenge, this colorful 2.8 magnitude cluster was probably discovered by Hodierna. Consisting of about 40 stars, its age is believed to be around 36 million years. It is very close to us at a distance of only 850 light-years. Take the time to closely study this object – for it is believed that due to the thinness of the galactic disk in this region, we are seeing two clusters superimposed on each other.

With the Moon out of the picture early, why not get caught up in a galaxy cluster study – Abell 426. Located just 2 degrees east of Algol in Perseus, this group of 233 galaxies spread over a region of several degrees of sky is easy enough to find – but difficult to observe. Spotting Abell galaxies in Perseus can be tough in smaller instruments, but those with large aperture scopes will find it worthy of time and attention.

At magnitude 11.6, NGC 1275 (Right Ascension: 3 : 19.8 – Declination: +41 : 31) is the brightest of the group and lies physically near the core of the cluster. Glimpsed in scopes as small as 150 mm aperture, NGC 1275 is a strong radio source and an active site of rapid star formation. Images of the galaxy show a strange blend of a perfect spiral being shattered by mottled turbulence. For this reason NGC 1275 is thought to be two galaxies in collision. Depending on seeing conditions and aperture, galaxy cluster Abell 426 may reveal anywhere from 10 to 24 small galaxies as faint as magnitude 15. The core of the cluster is more than 200 million light-years away, so it’s an achievement to spot even a few!

Saturday, March 24 – Today is the birthday of Walter Baade. Born in 1893, Baade was the first to resolve the Andromeda galaxy’s individual stars using the Hooker telescope during World War II blackout times, and he also developed the concept of stellar populations. He was the first to realize that there were two types of Cepheid variables, thereby refining the cosmic distance scale. He is also well known for discovering an area towards our galactic center which is relatively free of dust, now known as “Baade’s Window.”

Just after sunset, you really need to take a look out your western window for a really beautiful bit of scenery. As the sky darkens, look for the very tender crescent Moon lit with “Earthshine”. Above it you will see bright Jupiter. Above that you will see blazing Venus. And, if that’s not enough, just a little higher will bring you to the Pleiades! What a great way to start a weekend evening!

With the Moon so near the horizon, we have only a short time to view its features. Tonight let’s start with a central feature – Langrenus – and continue further south for crater Vendelinus. Spanning 92 by 100 miles and dropping 14,700 feet below the lunar surface, Vendelinus displays a partially dark floor with a west wall crest catching the brilliant light of an early sunrise. Notice also that its northeast wall is broken by a younger crater – Lame. Head’s up! It’s an Astronomical League challenge.

Once the Moon has set, revisit M46 in Puppis – along with its mysterious planetary nebula NGC 2438. Follow up with a visit to neighboring open cluster M47 – two degrees west-northwest. M47 may actually seem quite familiar to you already. Did you possibly encounter it when originally looking for M46? If so, then it’s also possible that you met up with 6.7 magnitude open cluster NGC 2423 (Right Ascension: 7 : 37.1 – Declination: -13 : 52), about a degree northeast of M47 and even dimmer 7.9 magnitude NGC 2414 (Right Ascension: 7 : 33.3 – Declination: -15 : 27 ) as well. That’s four open clusters and a planetary nebula all within four square arc-minutes of sky. That makes this a cluster of clusters!

Let’s return to study M47. Observers with binoculars or using a finderscope will notice how much brighter, and fewer, the stars of M47 are when compared to M46. This 12 light-year diameter compact cluster is only 1600 light-years away. Even as close as it is, not more than 50 member stars have been identified. M47 has about one tenth the stellar population of larger, denser, and three times more distant, M46.

Of historical interest, M47 was “discovered” three times: first by Giovanni Batista Hodierna in the mid-17th century, then by Charles Messier some 17 years later, and finally by William Herschel 14 years after that. How is it possible that such a bright and well-placed cluster needed “re-discovery?” Hodierna’s book of observations didn’t surface until 1984, and Messier gave the cluster’s declination the wrong sign, making its identification an enigma to later observers – because no such cluster could be found where Messier said it was!

Sunday, March 25 – Today in 1655, Titan – Saturn’s largest satellite – was discovered by Christian Huygens. He also discovered Saturn’s ring system during this same year. 350 years later, the probe named for Huygens stunned the world as it reached Titan and sent back information on this distant world. How about if we visit Saturn? You’ll find the creamy yellow planet located about a fistwidth northwest of bright, white Spica! Even a small telescope will reveal Titan, but remember… it orbits well outside the ring plane, so don’t mistake it for a background star! While you’re there, look closely around the ring edges for the smaller moons. A 4.5” telescope can easily show you three of them. How about the shadow the rings on the planet’s surface? Or how about the shadow of the planet on the rings? Is the Cassini division visible? If you have a larger telescope, look for other ring divisions as well. All are part and parcel of viewing incredible Saturn!

If you missed yesterday evening’s scenic line-up, don’t despair. Just after the Sun sets tonight – and above the western horizon – you’ll find the young Moon very closely paired with Jupiter. Keep traveling eastward (up) and you’ll encounter Venus. Continue east and the next stop is M45. Watch in the days ahead as the Moon sweeps by, continuing to provide us with a show! Need more? Then check out Leo and Mars! You’ll find a great triangulation of Regulus to the west, Mars to the east and Algieba to the north. If you didn’t know better, you’d almost swear the Lion swallowed the red planet.

Tonight let’s return to our previous studies of the Moon and revisit a challenging crater. Further south than Vendelinus, look for another large, mountain-walled plain named Furnerius, located not too far from the terminator. Although it has no central peak, its walls have been broken numerous times by many smaller impacts. Look at a rather large one just north of central on the crater floor. If skies are stable, power up and search for a rima extending from the northern edge. Keep in mind as you observe that our own Earth has been pummeled just as badly as its satellite.

On this day in 1951, 21 cm wavelength radiation from atomic hydrogen in the Milky Way was first detected. 1420 MHz H I studies continue to form the basis of a major part of modern radio astronomy. If you would like to have a look at a source of radio waves known as a pulsar, then aim your binoculars slightly more than a fistwidth east of bright Procyon. The first two bright stars you encounter will belong to the constellation of Hydrus and you will find pulsar CP0 834 just above the northernmost – Delta.

Unitl next week? May all your journeys be at light speed!