Click here to go ahead to Spring 2013, or click here to go back to Autumn 2012 "Eyes on the Sky" astronomy videos.
Comet C/2011 L4 PANSTARRS is a comet that is unexpectedly visiting our solar system. Discovered in 2011, but not reaching full brightness until this week, this cosmic interloper is thought to have originated from the Oort Cloud. It may be the only time it visits our inner solar system - and certainly the only time in our lifetimes! So how to see this 'dirty snowball' that has it's dust and ice heated by the Sun, which forms the visible coma and tail that we see? Well, with this comet, a bit of patience, clear skies, a low western horizon, and maybe a bit of luck. There are a number of useful charts out there on the internet, showing the location of the comet in a single graphic:
But here at Eyes on the Sky, the graphics are a little different. Rather than showing you how the comet might look, the graphics in the video above show the location of the Sun, comet, due west, and a grid of lines 10 degrees apart, along with the specific times and comet magnitudes listed. This way, you can measure you way to the comet by knowing where the Sun is, comparing it to your horizon, and measuring the comet's estimated location. This should make it easier to find this "naked eye but not necessarily easy to see or discern from a jet contrail" comet.
Daily graphics for Comet PanSTARRS (40 degrees N latitude charts)
Continuing with a similar area as last week's video, Eyes on the Sky looks towards the portions of the night sky that are nearby to Sirius, the brightest star in the nighttime sky. To the north of Sirius is a medium-sized open cluster, Messier 50. Finding this isn't terribly difficult, provided you have binoculars or a magnified finderscope on your telescope. The "head" of Canis Major provides some helpful "pointing" stars to help you hop your way towards this cluster of 200 or so stars. However, at ~3000 light years away, it is somewhat faint, and will either require very dark skies, or a telescope with moderate aperture to observe.
Towards the west, although a slightly further angular distance for us, is the twice as close 1600 light years away Messier 47. Though containing just 1/4 the number of stars, its proximity to Earth means that many of these stars are brighter, so even binoculars can pick this one off. But being closer means the stars appear more spread out, at twice the size of M50's. M47 spans nearly the size of the full Moon, so use low power in a telescope to see the blue white and yellow giant stars here. And don't forget to compare them to the 3400 light years away red giant just to the west of the cluster's location.
And don't miss this week's SkyLlights either!
See Star Chart #9 here for a detailed view of the stars around M50 and M47, and if you're not sure where exactly to find this area of sky, see here for general winter-time constellation locating tips.
Monoceros the Unicorn as a constellation doesn't exactly roll off the tongue, nor do a lot of amateur astronomers talk about this constellation. However, there is a surprising amount of objects to see here - likely because the Milky Way runs right through this constellation, just to the east of the better-known, and more obvious, Orion. Though the constellation itself may be dim - it's brightest stars are fourth magnitude, rendering the shape invisible to most light polluted areas - the objects within it can be found by "star hopping" from some brighter stars in the area to the objects within it.
Beta Monoceros can be found by drawing a line from the "belt" stars of Orion into the Unicorn itself. This triple star system was described by William Herschel as "...one of the most beautiful sights in the heavens,” clearly there is something to be seen here! To it's north, but better arrived at by following some of Gemin's stars and meandering south, is the Christmas Tree cluster, with the dark "Cone Nebula" within it (though the Cone is only visible from dark sky areas with larger telescopes). Anchored by 15 Monocerotis, the cluster isn't hard to find, and the Xi Gem / 15 Mon line takes the observer to a seemingly mundane 6th magnitude star, but which is one of the most fascinating to contemplate, even if we can't visually see what's happening there. Plaskett's star is one of the most massive double star systems known, it's 100 solar masses whipping around each other in a very short time period. And that star is not far from the Rosette Nebula which surrounds the star cluster NGC 2244.
See? There really IS a lot to see here! Look between the Orion / Gemini / Procyon / Sirius area, and have a look for yourself this week.
MONOCEROS STAR CHART - 800KB, PDF, or see Star Chart #9 here, or here for general winter-time constellation locating tips.
Also, as seen in the video from three weeks ago, Ceres and Vesta are still quite visible in Taurus.
The Moon travels along a path close to the ecliptic, which is the imaginary line in the sky traced by the Sun against the background stars as we rotate and revolve. The Moon's orbit around Earth is inclined somewhat to the ecliptic, and this week we can see clear evidence of that as it travels from Taurus, through Gemini and Cancer on to Leo. Along the way, it swings by the asteroid Vesta (see chart at right), Messier 1, Messier 35, Messier 67 and then the first magnitude star Regulus by Sunday the 24th.
As it travels, it will move from first quarter phase to nearly full phase. By the weekend, it will reveal one of the brightest areas visible on the Moon: The crater area of Aristarchus. You can see this naked eye, and better with binoculars, but the best way to view it is with a small telescope. There is significant detail visible here, so waiting for the Moon to be at / near the meridian will increase your chances of seeing more, though a steady atmosphere and a larger, well-cooled telescope will help most of all.
ARISTARCHUS REGION chart, PDF 1.3MB
Also, as seen in the video from two weeks ago, Ceres and Vesta are still quite visible in Taurus.
Mercury is a fast-moving planet; with an orbital period of just 88 days, it goes around the Sun about once every Earth season. And being an inferior planet, it is only visible in the morning or even sky for a few weeks at a time. This week is the best time to spot it until June, so get our your binoculars or small telescope, find a clear/flat horizon to the west, and hope for clear conditions.
Early in the week on the 11-th the very slim, young crescent Moon is just a few degrees away from Mercury, which will be the brighter object in the area. That's because Mars, shining back at Earth from it's position nearly across the solar system from us, is also visible nearby to Mercury, sitting slightly below it. But the best time of the week to see Mercury will be the weekend, when the planet reaches it's highest point above the horizon, called "greatest eastern elongation" - or it's point furthest towards the east (despite being located in the western sky). It may be possible to see Mercury about 10 degrees above your local horizon this weekend around 30 to 45 minutes after sunset.
Also, as seen in last week's video, Ceres and Vesta are still quite visible in Taurus. See the free PDF finder chart to the right for details on where to see each of these minor planets through the end of this month. And don't miss M41 in Canis Major; it is located in a wonderful position to see well around 8:00pm local time.
In between Mars and Jupiter, a number of large, rocky bodies orbit our Sun. Not big enough to be designated planets, but large enough to be seen with minimal optical aid, these solar system oddballs are often overlooked, but they are worth watching. Over the course of the next month, they are easy to spot in Taurus the Bull, and their motion changes quickly too - daily... errrr - nightly observations will demonstrate their quick movements compared to the background stars.
Ceres is decent-sized at over 900 kilometers, and Vesta is somewhat smaller, but still one of the larger asteroids at about 560 kilometers. Click on the chart for Ceres and Vesta at the right to download a free PDF chart for the motion of each of these minor planets this month. Binoculars should pick them off in all but the worst light polluted areas, and a small telescope will easily display their star-like appearance, but keep watching them this month to observe their non-star like changes.
Also, don't miss the conjunction of Mars and Mercury as the zippy messenger planet passes the red planet on February 8th, and take a look at M42 in Orion while the nebula is still high in the sky this month.
Capella, in some ways, is much like our Sun; yet in others, quite different. How do we know this? Astronomers know a lot about the composition, size, luminosity and temperature of stars simply by measuring and understanding one important scientific tool: Spectroscopy. When light is split into a rainbow of colors, that continuum of color displays certain spots where elements like lithium, calcium, carbon, and other "metals" (any non-hydrogen / non-helium element) show up as darker lines. 100 years ago, as astronomers struggled to understand these various spectral lines and classifications, they started with an "A through N" system. As the lines were understood, astronomers could classify these stars in order of temperature, which placed "O" and "B" before "A." It also wound up dropping quite a few other letters, so today we are largely left with this stellar classification ordering:
As you can see from the video thumbnail above, there is an easy way to remember this by using a simple mnemonic device of "Oh, Be A Fine Girl(Guy) Kiss Me." For those of us in amateur astronomy, there are ways to see the differences in color of these stars too. The chart link below lists the brighter B-A-F-G-K-M stars in Auriga that can be seen (mostly) naked eye. But if you use a telescope, you can see the color more clearly. Use a smaller aperture such as 60 to 90 millimeters, center each star, and slightly defocus it. By doing this, the light from the star is slightly spread out and the color easier to perceive.
Auriga spectral classification chart (900KB, PDF)
This week the Moon reaches full on the weekend; that means all week long there is something new and different to see along the terminator. Because of libration (the tilting and rocking of the Moon in it's orbit from our perspective on Earth), this week we can see more of the northern edge of the Moon. Along the northern latitudes are some well-known and visually explored craters, such as Plato between Mare Frigoris and Mare Imbrium. But water ice was recently discovered to exist in some craters near the Moon's north pole - there are 3 charts below to help you spot some of the craters in this area:
Correct image view, northwest Moon
Upright / mirror-reversed, northwest Moon (use this chart for refractors/SCT's using a star diagonal)
Upside-down / mirror reversed, northwest Moon (use this chart for reflector telescopes)
These are somewhat large files at about 3MB each, and will require the use of a PDF reader to see/download them.
Jupiter's four brightest moons, discovered by Galileo Galilei in 1601, may be somewhat similar in size, but they couldn't be more different in personality. The closest, Io, is volcanic from it's proximity to the planet and the tidal heating that causes. Europa, likely sporting an ocean underneath it's frozen surface, is not only the smallest of the four, but one of the smoothest objects in the solar system. Heavyweight Ganymede, the largest moon in the solar system, is an a resonance pattern with the preceding two. And Callisto, the furthest from Jupiter, is smaller than Ganymede, but has a tenuous atmosphere and may also have liquid ocean below. And all of these moons can be seen with simple binoculars from Earth.
The planet itself is interesting as well: Cloud bands of frozen ammonia and ammonium hydrosulfate dominate our visual view, which includes equatorial bands seen in even the smallest telescopes and the Great Red Spot, which can be a challenge to see when its color is so close to the two main belt colors. Here are some tools to help you better spot and identify the Jovian features and motions:
Where is Io - a free app for Android smartphones that plots the current Galilean moon positions, and out for the next few days. Unfortunately, I do not know of a similar free app for Apple products.
Project Pluto Great Red Spot transits by month - because clouds don't necessarily rotate like a solid body, some of these times may be off, but it is a listing of when the Great Red Spot will be transiting the middle of Jupiter (approximately) through the end of 2013. Note that all times given are UTC, so you'll need to convert to your local time.
Orion is such a distinctive constellation, many people have seen it, and may not even realize what they have seen. The bright stars Alnitak, Alnilam and Mintaka forming its near-perfect belt, surrounded by the similarly bright Betelgeuse, Bellatrix, Rigel and Saiph make for stars that instill awe and wonder... and stories. Learn the some of the Greek mythology about this constellation, plus what's visible within it's borders near Orion's 'sword'. Under dark skies naked eye, the "fuzzy star" as the middle "sword star" is clearly evident, and progressively more revealing with more aperture. Binoculars increase the extent of the nebulosity visible, and telescopes start to display the detail - and sometimes color - of this burgeoning stellar nursery.
Find out what you can find and see here, along with a few oft-overlooked objects in the same field of view as the Great Orion Nebula, as Messier 43 is part of the same gas cloud, and Iota Orionis is the next star south from the larger nebula region. For a star chart of Orion, click here.
Lepus the Hare often gets the short end of the stick - err... telescope, because most people are looking at the fabulous targets in Orion. But there's something interesting to see there, which is out of place too: The globular cluster Messier 79. A remnant of the Canis Major Dwarf Galaxy, this cluster (along with the galaxy) was gobbled up by our larger, more massive Milky Way galaxy. Learn where to find this constellation and object in the night sky. And if you are looking to find the two other globulars mentioned in the video, check out these star maps here:
NGC1851 - in the constellation Columba, which is even further south than Lepus. The globular is nearly 15 degrees due south of M79 Will require looking when the constellation is right at the meridian for most observers in Northern Hemisphere.
NGC2298 - Use the same chart as above. Though not listed on it, NGC2298 is exactly 3.5 degrees south of the star Kappa Canis Minor, even though the globular is in the constellation Puppis. The good news is that this cluster is 15 degrees above the horizon for those at 40 degrees latitude (higher if you're further south), so it's at least possible from 45 degrees north when it's on the meridian. But you'll need a low horizon to the south, and almost no light pollution that direction too.
Also, don't miss the Quadrantid meteor shower, though this year it isn't ideally timed for American and European viewers.
Jupiter, the Moon, the Hyades and Aldebaran are all nestled up close to each other on Christmas day. Hopefully the clouds stay away for you so you can see this tight grouping of celestial objects. And check out the "Best of Eyes on the Sky" for 2012 later in the video too.
Here's the sequence of events for the dual moon transit across the fact of Jupiter
12:08 UTC, Ganymede'd disk starts its transit across Jupiter.
14:12 UTC, Ganymede's disk finishes its transit across Jupiter.
14:32 UTC, Ganymede's shadow starts to cross Jupiter.
15:56 UTC, Io's disk starts its transit across Jupiter.
16:34 UTC, Io's shadow starts to cross Jupiter.
16:34 UTC, ** Dual-shadow event starts at this time. **
16:50 UTC, Ganymede's shadow exits Jupiter's disk.
16:50 UTC, ** The dual-shadow event is completed. **
18:08 UTC, Io finishes ots transit of Jupiter.
18:46 UTC, Io's shadow exits Jupiter's disk.
Convert your time for Universal Time (this event will not be visible to most of North America, though the very end of it may be visible in western Europe).
Early in the evening this week, the Summer Triangle stars and their attendant constellations are still visible in the western sky - odd, in a way, given that the winter solstice also occurs this week on the 21st! But as winter progresses, these stars will drop out of view, and we find ourselves witnessing the brighter stars and constellations of winter. What can we expect to see?
So get prepared for those long nights, and plenty of bright stars in those skies to guide you to the fascinating celestial sights of winter.