Monday, April 2 – Today in 1889, the Harvard Observatory’s 13″ refractor arrived at Mt. Wilson. Just one month later, it went into astronomical service at Lick Observatory, located at Mt. Hamilton. It was here that the largest telescopes in the world resided from 1908 to 1948. The 60″ for the first decade, followed by the 100″. This latter mirror is still the largest solid piece ever cast in plate glass and weighed 4.5 tons. Would you believe it’s just 13 inches thick?
Today in 1845, the first photograph of the Sun was taken. While solar photography and observing is the domain of properly filtered telescopes, no special equipment is necessary to see some effects of the Sun – only the correct conditions. Right now Earth’s magnetosphere and magnetopause (the point of contact) are positioned correctly to interact with the Sun’s influencing interplanetary magnetic field (IMF) – and the plasma stream which flows past us as solar winds. During the time around equinox, this leaves the door wide open for one of the most awesome signs of spring – aurora! Visit the Geophysical Institute to sign up for aurora alerts and use their tools to help locate the position of the Earth’s auroral oval.
Tonight’s Full Moon is often referred to as the “Pink Moon” of April. As strange as the name may sound, it actually comes from the herb known as moss pink – or wild ground phlox. April is the time of blossoming and the “pink” is one of the earliest widespread flowers of the spring season. As always, this Moon is known by other names as well, such as the Full Sprouting Grass Moon, the Egg Moon, and coastal tribes referred to it as the Full Fish Moon. Why? Because spring was the season the fish swam upstream to spawn!
Tuesday, April 3 – If you’re up well before dawn this morning, be on alert as the Moon is within about one degree of Spica. For many parts of the world, this could mean an occultation, so be sure to check IOTA information!
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With very little time before the Moon rises tonight, let’s begin a new adventure as we move into the constellation of Cancer. This will be an ideal time to familiarize yourself with its dim stars and one very bright open cluster. Try using both Pollux and Procyon to form the base of an imaginary triangle. Now aim your binoculars or finderscope near the point of the apex to discover M44 – the Beehive.
According to ancient lore, this group of stars (often called the Praesepe) foretold a coming storm if it was not visible in otherwise clear skies. Of course, this came from a time when combating light pollution meant asking your neighbors to dim their candles. But, once you learn where it’s at, it can be spotted unaided even from suburban settings. Hipparchus called it the “Little Cloud,” but not until the early 1600s was its stellar nature revealed.
Believed to be about 550 light-years away, this awesome cluster consists of hundreds of members – with at least four orange giants and five white dwarfs. M44’s age is similar to that of the Pleiades, and it is believed that both clusters have a common origin. Although you won’t see any nebulosity in the Beehive, even the very smallest of binoculars will reveal a swarm of bright stars and large telescopes can resolve down to 350 faint stars. Capture it tonight!
Wednesday, April 4 – While you’re out tonight, be on watch for the Kappa Serpentid meteor shower. Its radiant will be near the “Northern Crown,” the constellation known as Corona Borealis. The fall rate is small with an average 4 or 5 per hour.
With a bit more time to spare before the Moon interferes, look again to identify the upside down Y of the constellation of Cancer. If you can spot M44, the star just south of it is Delta. About three fingerwidths southeast of Delta is Alpha, and we’ll begin by exploring this star.
130 light-year distant Alpha Cancri – Acubens – is around 4th magnitude and is also a great double star for a small telescope. Its name translates as the “claw” and you will find it clutches a disparate 11.8 magnitude companion star nearby.
Now hop just one fingerwidth west for a stunning sight – galactic cluster M67. Hanging out in space some 2500 light-years away and containing more than 500 members, this grand cluster is a rule breaker in age. Believed to be about 10 billion years old, it is one of the oldest star clusters in our galaxy. Its stars have literally “switched off” from the main sequence, and have passed through the red giant stage and are returning back to their blue youth!
In binoculars you will see it as almost galaxy-like in structure, while even small telescopes resolve individual stars. Large telescopes will reveal stars beyond stars, like a globular cluster that has been smeared across the night. It is truly one of the most beautiful and mysterious of all open clusters.
Thursday, April 5 – We’ll return again tonight to Cancer to have a look at some curiosities. The first is about four fingerwidths away from Delta – Zeta Cancri. Its name is Tegmeni and it is a handsome double star for the small telescope. Both components are nearly the same magnitude and neatly split for mid-magnification ranges.
About a fingerwidth due east is V Cancri – a Mira-type variable star. While many such variables are difficult to follow with amateur equipment, V Cancri breaks the rules. It changes from magnitude 7.9 to magnitude 12.8 in a period of 125 days. When it swells to its maximum, it reaches a size about that of the orbit of Mars.
For those of you who use only your eyes to observe – look again at the Beehive and concentrate on Delta to the southeast. Known as Asellus Australis, this is a yellow optical double star often called the “southern donkey.”
Friday, April 6 – The weekend has arrived at last and the early evening will buy us some time to do some galaxy hunting in Cancer. You’ll find NGC 2672 just about a degree northeast of Delta.
At magnitude 12.3, it’s a galaxy meant for a larger scope. This small elliptical is noteworthy because it also has a companion – NGC 2673 – on its eastern edge. Now we’re entering the realm of 15th magnitude studies and very large telescopes only. Just slightly to the southwest, see if you can spot NGC 2677 as well. This one is extremely challenging.
If you’re enjoying this small cluster of galaxies, move no more than a third of a degree west, or let the field drift. Your reward will be another galactic pair – NGC 2667. These are so close as to be in the same field at high power, and are designated as A and B galaxies. Be aware that they require very averted vision and they are among the most difficult of studies! Look for two almost stellar nuclei…
Saturday, April 7 – If you are up in the wee hours of the night, be sure to look for Antares extremely close to the Moon. This could be an occultation for some parts of the world, so be sure to check IOTA information.
Today in 1991, the Compton Gamma Ray Observatory (CGRO) was deployed. While it may sound strange, this observatory sees the sky in gamma ray photons. These photons go off the edge of ultra violet – imperceptible to the human eye. Unfortunately, we can’t study gamma rays from Earth because our atmosphere blocks it, but the CGRO has shown a universe beyond our direct comprehension.
If there were a place that we could choose to look at in gamma rays, Cancer would be prime. Riddled with quasars, this constellation has got to produce some amazing things! Have a look at a quasar for yourself tonight. You’ll find 0839+187 about half a degree away from Delta Cancri. 0851+202 lies two degrees northeast and 3C215 is five degrees east-southeast. 3C212 and 3C208 are within two degrees north of Alpha, and are less than a degree apart, with radio source 3C208.1 in between them! While they will appear as nothing more than stellar points located in the center of the images, these are quite probably our only visual points of reference for the black holes at their hearts.
While you’re out, watch for bright streaks belonging to the Delta Draconid meteor shower. Its radiant is near the Cepheus border. The fall rate is quite low with around 5 meteors per hour and your best chance is before the Moon rises!
Sunday, April 8 – If you are up before dawn this morning, be sure to have a look at the sky as Jupiter makes a very scenic appearance less than a fistwidth away from the waning Moon.
With tonight’s dark skies, it’s time to go Herschel hunting again as we take on spiral galaxy NGC 2775. You’ll find it located roughly five degrees southeast of Alpha Cancri.
At magnitude 11.8, this elongated spiral with a bright core is suited to mid-sized telescopes. Some 60 million light-years away, NGC 2775 is a curious spiral galaxy. Its bulging core region and tight pattern of spiral arms have been home to five supernova events within the last 30 years.
For those with very large telescopes, there is a reason why NGC 2775 is an active region. To its northeast is NGC 2777, an amorphous galaxy with a tidally interacting, uncataloged companion – a situation which also exists in the more studied M81/82 system. NGC 2777 is producing a streamer of material flowing towards NGC 2775, yet the “companion” lies between them – possibly a galaxy in formation. Northeast is NGC 2773, which is far fainter, but still achievable with a large scope. Even if you only catch NGC 2775, you’ve not only captured another Herschel, but Caldwell 48 as well!