The website I use to determine the best viewing locations for ISS transits is www.transit-finder.com. It allows you to designate your home latitude and longitude and select a travel radius and range of dates (about a month ahead). I picked 140 km as a travel radius, and it give me the transits that are within a couple of hours driving distance from Owen Sound, ON. There is one lunar transit of the superMoon on Dec 3 and two solar transits in December as well, Dec 8 and Dec 12. Some details for those are provided below.
December 3: This lunar transit occurs across the Full Moon but the ISS is not illuminated this time so you have to be watching at the right time (10:11 pm EST ) for the passage of the ISS silhouette, Centreline of the transit is from just S. of Sauble Beach over Allenford and thence SE towards Keady, Markdale, Flesherton and eventually Toronto. (See second map below). This is a short transit of about 1 second silhouetted against the bright super full Moon) with the moon 48° above the western horizon. Time is Dec 3 at 10:11 pm EST. Check www.transit-finder.com for the path in your area if you are outside of Bruce-Grey.
December 8: This solar transit occurs in mid-afternoon at 2:33 pm EST and lasts about 3 seconds as well but the outline of ISS should be visible for the entire time. The Sun is just about in the same position in the sky as the lunar transit two weeks earlier. This time make sure you use solar filters on your telescope. This is the Sun you are looking at! Area of visibility is about the same coincidentally as the lunar transit of Nov 24, but centred over Hope Bay and Cape Croker. Howdenvale is well-placed.
December 12: Another solar transit occurs with a track of visibility farther south this time and visible Port Elgin to Big Bay. The Sun is a bit higher and the transit is fast -only 1,5 seconds. Be looking at 12:41 pm EST or so. Once again check out transit-finder.com for exact times for your location. Once again, proper solar filters for your telescope are required.
Lately I have taken to observing ISS transits of the Sun and Moon. These occur much more often than solar transits of planets (which are only possible for Mercury and Venus, both of which I have seen). Of course, no planets can pass in front of the Moon (unless we get a stray asteroid or other object in transit) but the International Space Station does this on a regular basis.
So far I have spotted one lunar and one solar ISS transit (Oct 4 and Oct 9) and have reported on the former event in the SGN issue for Nov 2017 (pg 5).
The website I use to determine the best viewing locations for ISS transits is www.transit-finder.com. It allows you to designate your home location latitude and longitude and select a travel radius and range of dates (about a month ahead). I picked 140 km as a travel radius, and it gave me 8 transits from Oct 30 to Nov 22, including the two described below.
The morning sky is the place for planet groups right now and will be until the end of 2017. Venus, Jupiter and Mars are located along the ecliptic over a span of about 30° and they are joined by the last crescent Moon in mid-Nov and mid-Dec. Check Coming Events and Sky Sights on this website for details about some of the more interesting events.
The planets and Moon in the eastern sky before dawn are the backdrop for two interesting lunar transits by ISS that happen on the mornings of Nov 14 and Nov 15. The ISS (with a crew of 6 aboard) will be visible each morning crossing the sky from west to east. On Nov 14, around 5:56 am EST, look northwest and halfway up to the zenith. ISS will be bright that morning reaching -3.8 magnitude, -as bright as Venus! The heavens-above star map for the track of ISS is below.
ISS will appear as a very bright moving point of light crossing the sky from NW to SE and towards the crescent Moon above the south-eastern horizon. For most of us in Grey and Bruce, it will just miss the Moon, but if you are on the Cabot Head Rd about 4 km south of the lighthouse, you will see it pass right across the lunar crescent! (See the inset box on map below). The ground track of the ISS shadow is like an eclipse shadow with a specific width and path and is show shaded in blue on the Google map below. The only place it crosses land close to us on Nov 14 is across Cabot Head on the Bruce. The rest of the track is over Georgian Bay although it reaches land again in the Wyevale area and Horseshoe Valley. The location of the only observing spot for Bruce-Grey is shown below.
The pass of the ISS downwards across the crescent Moon will take about only 1.8 seconds and it will be illuminated so you will be able to follow it as it approaches the Moon quite easily.
A repeat of this happens again the next morning on Nov 15 at 5:08 am EST. This time a wider audience can get a view, and anyone from Miller Lake to Cape Croker will see it even though the lead up will be much shorter. This time ISS comes out of shadow just before it encounters the Moon, so look at the crescent at the appropriate time and the space station will appear right above it and slowly drop down to cross the Moon’s thin face. Those of you living in Lion’s Head can see it from home if you have a low enough eastern horizon where the Moon can be seen above the trees. (I suggest the Isthmus Bay Road which is where I will be set up if the weather allows).
The two maps from transit-finder.com show the entire track across the Bruce (above) and a close up of the the track across Lion’s Head (below). Isthmus Bay Rd about 2 to 3 km from “city centre” is a good location to view since it has a nice clear horizon to the east where the crescent Moon will be rising. This pass lasts about 4.5 seconds which is close to the maximum that can occur. Lots of time to get a good look at the ISS! I suggest you fill the FoV of your scope with Moon and watch the action! And if you get some images please let us all have a look by posting them here. I guarantee HOME page coverage.
Intentionally crashing a 5600 kg spacecraft into a planet does not sound like a good thing, but controllers at the NASA Jet Propulsion Lab in Pasadena, California will do just that to end a multi-billion (that “b” is not a typo) dollar mission that has been studying Saturn for the last 13 years. It happens on Sep 15 and it is, in fact, the smart thing to do. One of the discoveries made by Cassini, the vehicle in question (think fully-loaded, over-sized SUV), is that one of the moons of Saturn probably has an ocean under its ice layer that could harbour some form of life. If the spacecraft contaminated that moon with earthly bacteria (spacecraft are routinely sterilized but you can’t keep a hardy bug down), it would not be a good thing. It is much wiser to vapourize the vehicle intentionally in Saturn’s atmosphere where the incineration would reduce everything to sterile atoms.
But even to the very end Cassini’s instruments will be wringing out information about Saturn. To quote Linda Spilker, Cassini project scientist from NASA’s Jet Propulsion Laboratory,
"The Cassini mission has been packed full of scientific firsts, and our unique planetary revelations will continue to the very end of the mission as Cassini becomes Saturn’s first planetary probe, sampling Saturn’s atmosphere up until the last second. We’ll be sending data in near real time as we rush headlong into the atmosphere – it’s truly a first-of-its-kind event at Saturn."
The data about the composition of Saturn’s atmosphere will be added to the wealth of other data and terabytes of images sent back by the spacecraft over the last 13 years. The discoveries have increased our knowledge about the planet immensely; where we had a single chapter in astronomy texts on Saturn, now there are literally dozens of volumes of information about the planet. As of December 2016, there were 3700 papers published in scientific journals using the data from this mission and it is not over just yet.
Cassini has clearly transformed our knowledge of the planet. Starting with the beautiful feature visible in telescopes from Earth, Saturn’s rings, Cassini found a highly dynamic system of particles constantly changing over time. Another surprise were the small moons embedded in the rings; these carve out gaps leaving behind beautiful sinuous patterns in their wakes. The dynamics of the rings of Saturn have revealed secrets about how planets form around stars and give insights into how our own planet may have coalesced from the dust circling our Sun in our early solar system.
As some discoveries have solved mysteries about Saturn, other mysteries have arisen as scientists scramble to analyze the data coming in. This includes giant hurricanes at Saturn’s poles, one with bizarre hexagonal sides unlike anything ever seen. How can this pattern be maintained over time? The number of scientific papers will continue to grow as planetary meteorologists propose theories to explain this unusual structure and other weather patterns in Saturn’s immense atmosphere.
Cassini also studied the dozens of moons circling Saturn and discoveries of wonderful things have involved them as well. Plumes of water vapour stream up from Saturn’s moon Enceladus, indicating a sub-surface ocean that is a possible abode for living organisms perhaps like those near Earth’s own deep ocean vents, the “black smokers”. The Cassini mission to Saturn also involved a smaller spacecraft called Huygens, which piggy-backed on Cassini from Earth and was released to parachute into the atmosphere of Titan, Saturn’s most enigmatic moon. There it found hydrocarbon lakes and rivers containing organic compounds, -a world where the chemistry may resemble our early Earth giving us a possible look back at our own evolution.
I highly recommend a look at the NASA Cassini website for more about the spacecraft and its discoveries, including some of the most spectacular images of Saturn, its rings and moons that I have ever seen. The link is provided here.
Goodbye, Cassini. You have served us well!
Twenty-six BAS members made the drive and set up camp at the KOA campground outside of Grand Island, NE to observe the total solar eclipse.
It started innocuously enough. “First contact," someone shouted. Huh? I could not see anything, other than the perfect sphere of the sun.
Then, suddenly, I saw it. Instead of the perfect spherical 360 degrees there was the tiniest indent of a black concavity, where I had not expected to see it at all. It grew slowly, in my filtered, safe, solar telescope, gnawing steadily, persistently at the orange-yellow wheel of cheese, slowly eliminating it. Nothing else was happening. Sunspots were being gobbled up, one by one. Huge solar flares were being quenched one by one. Inexorably, our sun was disappearing into the maw of dark shadow overtaking it, but the world nonchalantly kept fiddling, oblivious to the cosmic drama in the sky that only I and 20,000,000 other geeks were anxiously witnessing.
After about an hour and a quarter, a sudden chill was in the air. Then a noticeable greying. Something was HAPPENING! Relentlessly, that grey deepened, the temperature plunged, the wind rose. Suddenly a single diamond of light, then even it was quenched. An eerie darkness cloaked us. Stars and planets shone in the sky.
The horizon was a panoramic reddish sunset, all around, and the chill grew deeper. The disc of our sun was obliterated except for a faint wreath of flames, and a wide wreath of glory radiating at least twice the diameter of the disc laterally in each direction and one diameter vertically. I wonder if the Coronal discs of glory around the saints' heads and Christ's head in icons was not originally conceptualized on manifesting the sun's corona in the death of an eclipse. Only such a death makes it visible.
The chill was profound. All was silence and awe, except for shuttering/shuddering cameras in all directions. Suddenly another brilliant diamond appeared on the opposite side. A shout spontaneously welcomed it. The epiphany was over, the glory was gone. The crippling doom raced eastward.
Confused birds began to fly again as the earth awoke from its nightmare. The cicadas took longer - hushed by the unnatural chill, awed by the doom that almost was. It was at least an hour before they began to sing again.
As a satellite in our solar system, Earth’s Moon is actually one of the larger ones, ranking 5th biggest in diameter. Only three moons of Jupiter and one of Saturn, appropriately called Titan, are larger. Ganymede, circling Jupiter, holds the number one spot at 5262 km across, half again as big as our Moon which is 3475 km in diameter. Six of the several hundred planetary satellites in our solar system are actually bigger than the former planet, Pluto, now a “dwarf planet”, which I think puts it in its proper place.
The four large moons of Jupiter are interesting to watch in a telescope as they circle the giant planet especially when one (or more) cast shadows onto Jupiter’s disk. Through our telescopes, we can actually see the shadows produced by these moons during their eclipses and can follow the dark blots as they pass across the face of the planet.
Our own Moon also casts a shadow, and being on the surface of the Earth, we have the opportunity to put ourselves inside the shadow where it appears. All this comes together during a total solar eclipse.
The solar eclipse on Aug. 21 is the most spectacular astronomical event of the year and will probably be seen by millions of people. For about an hour and a half, the Moon’s 110 km wide shadow will travel diagonally across the USA from Oregon to South Carolina. Two dozen BAS members will be watching near Grand Island, Nebraska where we reserved campsites a year and a half ago. Many more casual observers in the 11 states the path crosses will likely clog up the highways to the shadow path on that date; one estimate predicts up to 7 million people may try to get to the narrow track at eclipse time.
The Moon may be large, but its shadow dwindles to a tiny dot by the time it reaches the Earth and only in that very narrow path, can one say that they have “caught” the Moon’s shadow. (it’s more like letting it pass over you for the few minutes of totality). I “caught” my first Moon shadow in the clear, cold sky above Gimli, Manitoba on Feb 26, 1979, over 38 years ago, and I still get goose-bumps on the back of my neck when I think about it. The shadow could be seen moving our way and then it swept over the group creating a 360* sunset. I could not help but shiver, not from the Manitoba cold but from the experience itself. And up in the sky an incredible sight! The corona, the outer atmosphere of the Sun appeared, wispy streamers like white, irregular flower petals, surrounding a black hole, the silhouette of the Moon. More shivers!
In the Bruce-Grey area on Monday, Aug 21, only a partial eclipse will be seen since the Moon misses crossing the centre point of the Sun. The maximum is at 2:30 pm DST, when 70% of the Sun will be covered. The partially eclipsed Sun will not be safe to view without solar eclipse glasses like those available from FotoArt or from suppliers like Rainbow Symphony or American Paper Optics online. SkyNews magazine July/Aug issue came with a pair as an insert and it may still be available at local outlets. Also a #14 (not #12) arc welders filter will provide safe viewing. Please note, none of these filters are to be used with binoculars or telescopes, they are for naked eye viewing and only for short intervals. Please be careful with your eyesight!
From Owen Sound, some part of the Moon’s silhouette will be visible on the Sun from 1:08 pm DST to 3:45 pm DST. If you are further north or south, times may vary by several minutes; first contact occurs later if you are north of Owen Sound’s latitude and earlier if you are south.
So if you are stuck on this local part of Earth on Monday Aug 21, at least have a quick look at the Sun with solar eclipse glasses around 2:30 pm or so. And on Sep 6 at 7 pm, you are welcome to join BAS at the Fox Observatory as we recap the event from the path of totality. Here’s hoping for cloud-free skies (all over North America) on Aug 21!
Amateur stargazers, cottagers and nocturnal animals are really lucky to be living in Bruce and Grey counties. Stargazers have dark skies and bright stars to observe. Cottagers (away from overly-lit urban areas) have dark skies and a beautiful swath of summer Milky Way overhead when the family is out cooking weenies over a campfire. Nocturnal animals that live near or in the Bruce Peninsula Biosphere Reserve have nighttime darkness to which they have adapted over the millennia -no pesky streetlights making them well-lit targets for predators.
The common theme here is, of course, dark skies and a natural environment. Many places like the Bruce Peninsula Fathom Five National Park and the Bluewater Outdoor Education Centre are still mostly pristine environments and from a stargazing perspective, protected from unnecessary nighttime lighting, be it incandescent, florescent, or the most recent abomination, LEDs.
Keeping a dark nighttime environment is crucial for human health. Just google “Dark skies human health” for dozens of medical studies that support this contention. Fortunately, in the Bruce/Grey area of Ontario, nighttime over-illumination is only a problem in a few localities. Furthermore, efforts to preserve the dark nighttime environment locally have borne fruit. There are 17 Dark Sky Preserves in Canada, and four of them are within a 160 km radius of Wiarton. The four include Bruce Peninsula National Park near Tobermory, the Bluewater Outdoor Education Centre near Wiarton, Gordon’s Park on Manitoulin Island, and Torrence Barrens near Gravenhurst. Yes, locally we are optimistic about controlling light pollution, but the planet-wide scene is decidedly much the opposite.
Not to mince words, overall, we are losing the battle to control nighttime illumination. You just have to look at an image of the Earth at night from space to see how bright it is at night. Satellite cameras detect the totally wasted light sent upwards. Much light reflects back down from dust particles and water vapour and brightens the sky generally. The effect is visible even in rural areas as the visibility of faint objects is reduced. Even from 100s of kilometres away, the light domes over our cities cast an orange glow into the sky. Anywhere near or within a large city, the glare from overhead lights is extreme, allowing only light from the Moon and bright planets to get through. Fainter objects are totally invisible.
Click on image below to download a copy
A study in 2016 authored by Fabio Falchi of the Light Pollution Science and Technology Institute in Italy and Chris Elvidge of the US National Oceanic and Atmospheric Administration (along with other international scientists) has found that in the USA, for ex., 80% of the population cannot see the Milky Way from where they live. The percentage is the same in urban Canadian areas like those along the Windsor to Montreal corridor. The darkest skies on our planet are of course, in areas like the Canada northland and in countries like Madagascar, the Central African Republic and Greenland, where everyone can see the Milky Way by just stepping outside. [The original paper is available here.]
I am lucky to be able to see the Milky Way from my back yard because my house blocks the city lights to the north but there are sickly yellow-orange glows along parts of the southern and eastern horizon. Of course, like other large towns and cities, no Milky Way is visible from downtown Owen Sound. The situation locally has gotten worse in the last few years because the city recently replaced the majority of their streetlights with LEDs. These are certainly more economical and do have proper shielding to prevent upward light spill, but the overall level of lighting has increased approximately 30%, so the total light reflected from the ground upwards (especially in winter) has increased by a large fraction. Many people have commented to me that they find the lights at night overly bright. I agree and have the measurements to prove it.
On Saturday afternoon, May 27, there is an opportunity to visit a Dark Sky Preserve during the Open House at the Bluewater Outdoor Education Centre. The Bluewater Education Foundation and Ducks Unlimited Canada are co-sponsoring this event and it is open to everyone. You are welcome to come to the Outdoor Ed Centre (maps on the BAS website given below) and enjoy the wagon rides, birding, hikes, and fun kid activities like critter-dippin’ and face painting. Events start at 1 pm and will include solar observing with (safely-filtered) telescopes from the Fox Observatory. Everyone is welcome and after the Sun goes down, the observatory will be open for some dark sky viewing. Come and see what a Dark Sky Preserve is all about.
Check www.bluewaterastronomy.com for more information.
Considering that I have been a stargazer most of my adult life, you might think that I have seen a lot of strange things in the sky. The answer to the question: “Seen any UFOs?” is pretty simple: “No.” This lack of UFO sightings on my part is perhaps remarkable. After all I am out two or three times a week (weather permitting) looking at the sky with a variety of telescopes and cameras. I have taken close to 5 000 pictures on film, and more than three times that number of digital images. This is by no means unusual for a die-hard stargazer like myself and I number myself among a million or more amateur astronomers around the world. The USA has about half of those and Canada probably has close to 50,000 or so.
There are rarely reports of unusual objects (UFOs) from this large group of sky-savvy folks. The simple reason is that people who know the sky well can identify 99.99% of what they see as natural objects. These include ordinary aircraft, bright glints of sunlight from satellites or moving points of light such as the International Space Station, meteors of various brightnesses, some exploding at the end, bright planets like Venus (the single object most often mistaken for a “flying saucer") and even bright stars refracting the colours of the rainbow when their light passes through the thick air near the horizon. I have seen Sirius, for example, flashing colours across the entire spectral range from red to violet.
There is, however, one incident that had me stumped, for a little while anyway. If I had not used all of my senses, I would be puzzled to this day. But it took only a simple observation to get an answer for the UFO that I saw. (it is now an IFO on my list - an Identified Flying Object).
It happened in May 1980, in Thompson, Manitoba chaperoning a group of Bruce County students who had won the right to compete in the Canada-Wide Science Fair. I had a great experience with that wonderful group of young people and several came back home with Canada-Wide awards. We were housed for several nights in a college residence and at night, (after my charges were safely tucked away in their rooms...) I would go out for an hour or two of stargazing and photography. The residence parking area (within sight of our rooms) was an ideal spot to view the northern sky and I came home with some good photos of aurora and some interesting planet groupings in the western sky. I was particularly impressed with how low Polaris was compared to its 45° elevation back home.
My UFO experience started rather simply with a moving point of light that was just like many meteors I had seen before. Then another one appeared from the same direction and split into two at the end of its path. “Wow”, I said, “a fragmenting meteor!” I went back to gazing at the stars and it happened again, but after the trail split, the two separate trails started criss-crossing each other! Meteors breaking up do not do this, so was this a UFO mother ship and scouts?. More trails appeared, even three together and some performed the same crossing pattern as before. I was stumped, but then I started actually hearing the meteors - a faint, swish, swish sound in the quiet of the night. It sounded just like the beat of wings of low-flying birds.
In fact, these UFOs were birds. The faint light was reflection from feathers covered with chemicals that make them water resistant and which also fluoresce in the UV light, spilling upward from the streetlights below. The flight paths of birds often cross from our perspective on the ground.
If I had only seen and not heard the event, it would have gone down in my book as a genuine UFO.
UFO sighting statistics always have a small percentage of UFO sightings that remain “unexplained." My contention is that if more details of the sighting were available or if an experienced sky-watcher was observing, most, even all, sightings could be explained. I know this will not satisfy those folks out there who want there to be extra-terrestrials visiting us, but my own experience and that of thousands of amateur astronomers familiar with the sky indicates otherwise.
If you have noticed a bright light in the eastern sky (perhaps while taking your pet for a walk) you are not alone. Venus in the west is gone (returning soon to the morning sky) and Mercury will not last long as a substitute evening star. Now we turn to the eastern sky to watch our next featured planet, Jupiter, a planet almost as bright as Venus, and in many ways much more interesting.
Jupiter is the largest planet of the 8 planets in our solar system (9 if you still pine for Pluto). Jupiter and our Sun constitute 99.99% of the total system mass and each has a gravity pull so strong that according to current theories, a major planet was prevented from forming in the space between -only jagged chunks of space debris, the asteroids, are found orbiting there. One Jove-centric pundit defined our solar system as “Sun, Jupiter and assorted debris”, and it is true that the “leftovers” don’t amount to much, mass-wise. Earth, of course, has water, an atmosphere, and conditions that allow living organisms to thrive, so it is pretty special. Jupiter is unique, too, but only because it is such an extreme contrast to our own beautiful world.
The gravity of Jupiter is over 2.5 times Earth’s so, if yours truly, at a trim 180 pounds, were on Jupiter, I would need to support 455 pounds just to stand up, if there was any place to stand. A solid surface like that on Earth cannot be found on Jupiter, and what we see in telescopes are the tops of swirling white and brownish clouds of ammonia crystals and darker-coloured sulphur compounds. Below the clouds (about 50 km thick) is a mixture of very cold hydrogen and helium gas which gets thicker and thicker all the way to the “surface” of a strange ocean of metallic liquid hydrogen. The atmospheric pressure here would crush the strongest pressurized vessel from Earth. So if the gravity doesn’t kill you, the pressure will.
Exploration of Jupiter can only happen from orbit or floating/flying in the upper atmosphere, but even here spacecraft are severely challenged. Wind speeds reach 1600 km/h (10 times those in Earth’s jet streams), and lightning occurs in “superbolts” the equivalent of 100 of the terrestrial variety. Huge storms in the atmosphere of this huge planet are common, -one Jovian hurricane, the Great Red Spot (first seen in 1665 and raging still) is bigger than the entire Earth with wind speeds over 400 km/h (twice those of a category 4 hurricane on Earth). Even Jupiter’s magnetic field is huge, extending several million km into space, so we are lucky that we are 600 million km away, -it is a safe enough distance.
Jupiter reaches a point in our sky called opposition on Apr 7 when it is exactly opposite the Sun and highest in our sky at midnight. This is prime-time for Jupiter, when it is well above the turbulent air near the horizon. But if it is cloudy Apr 7, don’t panic. Planets at opposition are in good viewing position for a month before and several months after the opposition date. For the best views on any clear night, observe the planet when it is away from the disturbing air near the horizon. Summer star parties will obviously feature both Jupiter and Saturn, which itself reaches opposition June 15.
Jupiter is near the star Spica, the brightest star of Virgo, but Spica does not move, so use it as a reference point to watch Jupiter doing what distinguishes planets from background stars, i.e. wander. Jupiter slowly slips westward until June 8 (retrograding), then, in the summer, it starts back towards Spica. By the end of Jupiter-viewing in autumn, the pair will be setting in the west just after sunset, with Jupiter closest to Spica and right above it.
Observing nights at the Fox Observatory will certainly include views of Jupiter with its always-changing arrangement of 4 bright moons. These are even visible in binoculars, but true to its status as King of Planets, Jupiter has 63 more moons circling it, the most of any planet. By Jove, Jupiter really is an attention-getter!
The variable weather of March prevented stargazers in the Bruce and Grey area from seeing Venus and Mercury as double evening stars on March 19. Though the daytime sky was a spectacular blue, a dense cloud moved in above the western horizon at sunset, hid the planets and even obliterated the Sun as it sank below the edge of Lake Huron. Amateur astronomers were again teased by the goddess of astronomy, Urania, but, on that occasion, she perversely hid her beauties from sight.
Though this is not the first time that clouds have defeated local stargazers, (weather cancellations average about 50%) we all understand the following: "whether or not it is clear to you...the universe is unfolding as it should": Desiderata, Max Ehrmann. If you read "weather" instead of "whether", the line has a slightly different meaning to be kept in mind as we attempt to observe future sky sights.
The next test of local stargazer’s dedication comes when Urania offers a series of crescent moon appearances near Mercury and Mars in the western sky from Mar 29 to Apr 1 (weather permitting, of course). The thin crescent Moon is a very pretty sight and should be high enough above the western horizon on Mar 29 to stand out in bright twilight. (See diagram). Right beside it, the only bright “star” in the area is the planet Mercury. This is an opportunity to spot that elusive planet if you have never seen it before, -it will be in the western sky playing the role of “Evening Star” for a few weeks. On March 30, the crescent Moon moves upwards and will be just left of Mars. On March 31, it appears close to Aldebaran, the “angry red eye” of Taurus the Bull. Aldebaran is indeed a red giant star, 44 times larger than the Sun, and does have a slight tinge of red to it. After April 1, the Moon continues moving eastward, increasing its phase (waxing) and brightening the sky as it does so. The Moon is first quarter on April 3 and full on April 11. April’s Full Moon is also called the “Egg Moon”, the “Grass Sprouting Moon” or the “Paschal Moon”.
Unlike Venus which had a three month period of visibility, the two planets presently in the western sky will not be around for long. On April 1, Mercury starts back towards the Sun and will be lost in the Sun’s glare by the time of full moon. Mars follows Mercury and is hidden in the Sun’s glow a few weeks later. The show is over by the third week of April.
Most of Mercury’s disappearing act is due to the rapid decrease in the amount of sunlight that reflects our way from its surface. Both Venus and Mercury exhibit phases as they orbit the Sun and on March 29, Mercury is half illuminated, -a first quarter phase. By Apr 6, this is reduced to a thin crescent (like the crescent Moon on March 29 and 30) and with less light reflected our way, the brightness of Mercury drops rapidly. With the weather in March so changeable, if you want to add Mercury to your life-list of astronomical objects, you need to observe on any clear night in the next two weeks or so.
If you join the Bluewater Astronomers on Saturday, March 25 at the Fox Observatory for the Messier Marathon, and you arrive before Mercury sets, ask one of the guides to show you the planet in a telescope. At medium power it is possible to see the planet as a thin crescent like a miniature crescent Moon. If you have a telescope of your own, Mercury is a neat sight; this month is your best opportunity to see it for the entire year. Don’t miss it!
Two very different planets are visible in the evening sky right now. Venus is obvious even in twilight, -a very bright Evening “Star” high above the SW horizon. Then there is Mars, much dimmer and slightly reddish -to the left and slightly up from Venus- looking like an average background star. Both are visible in February and March, Venus catching your eye instantly, its light so intense that most times clouds cannot block it. And now that you know where to look, you should be able to spot the Red Planet as well.
Venus, on Feb 17, was its brightest for this apparition since it had the largest sunlit surface facing us and was on the inside track of its orbit so it was also larger in area due to proximity. The two effects work against each other, -as the planet gets closer and larger, less and less of its surface is light from our perspective. There is a happy medium, however, on Feb 17 when the two produce a maximum lit surface. See SKY SIGHTS entry for Feb 17 for more.
The difference in visual appearance of the two planets is based mostly on distance. Venus in its orbit is approaching the Earth right now and on March 24, it passes between us and the Sun at a mere 41 million kilometres. On rare occasions, it can even shave another 3 million km off that figure. Mars is about 6 times farther than Venus right now and on the opposite side of the solar system from Earth. In a year or so, however, Mars and Earth will be much closer, only 56 million km apart and so Mars will shine as a bright planet in our sky once again. But because Mars is smaller than Earth, (half of Earth’s diameter) and reflects less light our way (16%) it can never get as bright as Venus in our sky. Venus is an Earth-sized planet and its thick atmosphere of clouds reflects 75% of the sunlight in our direction. Mars and our Moon are very poor reflectors with similar albedos (the technical term for reflectivity) of 16% and 12% respectively, about the same as a slate blackboard.
Both planets, Venus and Mars are named after mythological gods. The Roman goddess of love was Venus and in Greek mythology, she was Aphrodite. She is always depicted as demur, lovely and beautifully curvy. The Roman god of war, Mars, and the equivalent Greek war god, Ares are shown in statues and paintings as bold, handsome and certainly manly (and deadly in battle). As the story goes, Mars and Venus at one point were a couple and produced twin offspring which judging by their names were probably poorly behaved: Deimos (meaning terror or dread) and Phobos (panic/fear). These names are used for the two real moons of the planet Mars.
So in the summer of 2018, a much brighter Mars will be the planet to observe with surface features like ice caps and dust storms visible in a telescope. (Even Deimos and Phobos may be glimpsed). But Venus, though closest and brightest in our sky right now, will forever remain mysterious, never dropping her thick veil of clouds and revealing her surface features (unless you have radar eyes, of course). Do enjoy the naked eye or binocular views of Venus right now because by April, Aphrodite’s month, she passes behind the Sun and disappears from our western sky. Later in spring, Venus returns to the east as an equally bright Morning Star, but by then she has left Mars far behind. This is only a temporary separation as the two are back together in a spectacular “embrace” in October -stay tuned.
There is an “oh-so-close” lunar eclipse happening on Feb 10. Technically it is a miss, and even if the skies are perfectly clear, the best we can hope for is a slight darkening of part of the Moon’s face at the prime time of 7:44 pm. Even then, you might not notice anything unless you know exactly what to look for. Here’s what you need to know, (in case you’re interested).
Eclipses are caused by shadows. The Sun sends light out in all directions and during a lunar eclipse, the Earth blocks the Sun’s light and the Earth’s shadow falls onto the full Moon. Things have to be lined up perfectly, so eclipses don’t happen every month; the most we get is seven a year, about half of each type. In 2017, we get two solar and two lunar eclipses, a bit fewer than average.
Lunar eclipses would happen more often except that the Moon’s orbit around Earth is tilted and Earth’s shadow goes over or under the Moon most times. Secondly, there are two parts to the Earth’s shadow that can cover the Moon, an easily-seen dark central area, the umbra, and a surrounding penumbra, but it allows most of the sunlight through and is barely detectable. A penumbral eclipse is what we will get on Feb 10.
The shadow of Earth extends past the Earth and forms a dark cone stretching out to a point about 1,400,000 km away in space. That’s almost 4 times as far as the Moon is from us, so at the Moon’s distance, the shadow’s cross-section (a circle) is still big, almost 3 times as wide as the full Moon. For that reason, lunar eclipses last several hours and solar eclipses, with a much smaller Moon shadow, -only a few hundred km across- last only a few minutes.
The shadow of Earth on Feb 10 comes close but does not actually contact the umbra (it gets 99% of the way there). The second lunar eclipse this year, on August 7, is a bit better but still only partial and worse yet, for the whole eclipse, the Moon is below our horizon; the best view will be in the Middle East.
The one bit of good news for Feb 10 is that it may be possible to see a darkening due to the slightly darker, inner part of the penumbral shadow. The outer penumbra is just too faint to see when it touches the face of the Moon at 5:34 pm. By 7:44 pm, however, a darkening on the upper left edge of the Moon (about 10:30 on the clock) may be discernible for perhaps 20 minutes either side of the prime time. The only way to tell for sure is to take a picture at 7:44 pm and compare it to another taken two hours later when the eclipse is over and the Moon is back to full brightness.
If it is clear Friday night, Feb 10, the Fox Observatory at the Outdoor Education Centre near Oliphant will be open to the public and members of the Bluewater Astronomical Society will be there to show you the Moon. You are welcome to take a souvenir photo through the telescope, -even a cell phone will work. If the weather cooperates, there will be time to observe the eclipse, take photos and have a hot chocolate to ward off the chill. Do join us.
Here is an image from the April 4, 2015 lunar eclipse taken before umbral contact to simulate the appearance of the Feb 10 event. Notice the darkening in the upper left of the Moon's disk, -this is about where to expect darkening for the Feb 10 eclipse. This image was taken 10 minutes before umbral contact and the inside edge of the penumbra should be darker than this for Feb 10. Skies will need to be perfectly clear!
PS: The next good total lunar eclipse visible locally happens in two years on Jan 21, 2019 but only a year from now, on Jan 31, 2018, there is a good lunar eclipse visible from the west coast of North America if you are free to travel then. (I hear the skiing is good out there at that time, too). Mark your calendars!
On my astronomy calendar, the new year is marked by the anniversary of a night over 200 years ago (1801) that created a crisis in planetary astronomy. It was not immediately recognized as such, and the alarms were only heard in astronomical circles at first. The general public was mostly unaware that their universe was changing.
The event was the discovery of Ceres, an object that was called a “planet” for a while, then an “asteroid” and now is referred to as a “minor solar system body."
Guiseppe Piazzi, an Italian astronomer celebrated the first night of 1801 by discovering an unusual moving speck in a place where astronomers expected planets to be, and it came to be named Ceres (the Roman goddess of agriculture). Discoverers are allowed to suggest names, although the International Astronomical Union has final approval. There is some leeway in suggested names, however, and it’s OK (and a great idea) to name an asteroid after your spouse, -several discoverer’s wives have been immortalized in the heavens. However, the IAU will not allow naming a new asteroid or comet after your cat, for ex. Neither can anyone name a star after a loved one, not officially anyway. (Those websites are, in fact, a scam).
Twenty years before Piazzi’s discovery, on March 13, 1781, William Herschel added a 7th planet, Uranus, to the list so Ceres raised the planet count to eight.
Then in rapid succession, three additional “planets” was discovered, Pallas in 1802, Juno in 1804 and Vesta in 1807. The count stayed at 11 until 1845 when the astronomical “cup” overflowed.
In 1845 Astraea was discovered and the planet number went to twelve. Now things started to get complicated. In September 1846, an object was discovered that was different. The previous discoveries were star-like objects between the orbits of Mars and Jupiter, but this one was the most distant object ever observed. Furthermore, large telescopes showed that the object had a disk and colour similar to that of Uranus. Planet 13 (actually Neptune) was more like planet 7 (Uranus) than planets 8 through 12.
From 1847 on, new “planets” were discovered at the rate of about one a year and astronomers uncharitably started to refer to these objects as the “vermin of the skies”, not because they were ugly, (which they are - think debris from the exploding Death Star in Star Wars spreading out through space), but because there were so many of them.
The situation was resolved when William Herschel suggested that these objects should be put into a separate category of small “star-like” bodies that would be called “asteroids”. It was an intelligent suggestion especially as the numbers of asteroids continued to grow. There were enough ways to challenge students without asking them to memorize (in proper order) hundreds of new “planets”.
Astronomers now list more than 200 asteroids over 100 km in size, Ceres, the one that started it all, is 945 km across and Vesta is 545 km in diameter. The IAU recognizes 20 364 with names and there are thousands more that are simply given catalogue numbers. In all, there may be several million asteroids, but thankfully, most orbit between Mars and Jupiter and seldom stray to the vicinity of Earth to pose a danger.
Asteroid 4 Vesta is bright enough to be seen with the naked eye but binoculars make the task easier. See it for yourself over the next few months; the finder chart shows where to look. Join the two brightest stars of Gemini -Castor and Pollux - and extend the line down (eastwards) and you are in the right general area. Vesta should be the brightest object in view, but there is only one certain way to identify it. Make a quick star sketch (or take a photo) and then come back in a few days to see which “star” has moved. (This is how Vesta was originally discovered). Spot Vesta and you can add a named asteroid to your life list of astronomical objects. Only 20 363 more to go.
Detailed finder charts (both Vesta and Ceres) and photo hints are under the Charts & Forms tab. Good luck hunting “minor solar system bodies!"