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The Sky This Month - April 2017

A String of Galaxies

Before three quarter mark of 1923, astronomers knew our Milky Way Galaxy as being unique. Edwin Hubble changed all that with a historic image taken on Oct 6, 1923. He exposed a photographic plate at a hazy patch of light with the 100 inch Hooker telescope; the largest telescope in the world at the time. The results shocked the astronomical community. A newly discovered Cepheid variable observed within that patch of light led to the conclusion the variable was located in a separate galaxy other than the Milky Way.

An international team of astronomers using images from the Hubble Space Telescope have revised the number to at least two trillion galaxies in the known universe, a ten fold jump from older estimates. The Andromeda Galaxy is estimated to be 2.25 million light years away and is a favourite target at summer and fall star parties. From a dark site, you can see this remote object with the naked eye. Although Andromeda is still lost in early morning twilight for another few weeks, many other targets are at your disposal.

Starting from the constellation Ursa Major, many Messier galaxies line a pathway all the way down to the Virgo cluster consisting of dozens of galaxies. For example we find M106 located in Canes Venatici. This intermediate spiral galaxy is located 25 million light years away and lists as magnitude 8.4 and measures 19 by 8 arc minutes. The brightest galaxy of this constellation is M94 which is a slightly elongated, tightly wound galaxy with a very bright core. This 14 million light year object has a face-on orientation and glows at magnitude 8.2. This is a definite stop on your galactic survey. Detailed images show active star forming regions (in red) dotted along the outer edges of the galaxy like a string of pearls.

Move your scope less than five degrees to the west to swoop upon M63. Just a tad fainter then its Messier neighbour, the magnitude 8.6 also known as the Sunflower Galaxy has an estimated distance of 37 million light years and measures 10 by 6 arc minutes, keeping in mind the moon is 30 arc minutes wide.

Lower your telescope to the constellation Coma Berenices until you come across an inverted letter “Y”, more commonly known as Mel 111. Now that you are here, you must find and enjoy the edge-on beauty of NGC 4565 AKA the Needle Galaxy. Pretty well any instrument will reveal its sharp dust lane made up of dark interstellar clouds and star soot which obscures light. Take your time on this 31 million ly gem. Toward the upper boundary of this constellation is a pretty pair of 10th magnitude galaxies.

Not one but two comets are now visible. First is C/2017 E4 (Lovejoy) found low in the eastern sky before dawn in the constellation Pegasus. Lovejoy seems to have gone through a recent outburst and is presently magnitude 7.1 thus exceeding its predicted peak of magnitude 9 by mid April. It is an easy find in 50mm binoculars. Comet 41P/Tuttle-Giacobini is presently a circumpolar object at around 7th magnitude as well. Both comets do not sport a tail but show the distinctive green colour.

April 22/23 will be the peak of the Lyrid meteor shower. On that night/morning Earth will be passing through for debris field from Comet Thatcher. This is a long period comet as one lap around the Sun takes 415 years with its last visit in 1861. By midnight the radiant should be high enough to see the predicted 10 to 20 meteors per hour. With at said, outbursts of 100 meteors per hour have been observed in 1922, 1945 and 1982.  With a thin waning 13% illuminated cresent rising at 5 a.m. local along with Venus, skies will stay dark.

Jupiter will be at opposition on April 7 meaning it rises as the Sun sets and be the shortest distance from Earth. The Full Pink Moon occurs on April 11. This month’s moon also goes by the Sprouting Grass Moon, the Egg Moon, and the Fish Moon. New Moon occurs on the 26 (lunation 1167).

Until next month, clear skies everyone.

Gary Boyle

Twitter: @astroeducator

Author: Gary BoyleeNews date: Saturday, April 1, 2017Category: Northern SkiesFile:  2017 - 04 chart 1.png 2017 - 04 chart 2.pngTweet::  Pages

The Sky This Month - March 2017

Auriga

The star Capella is the most northern of the thirteen bright stars that help make up the winter sky. Referred as the alpha star of the constellation Auriga, Capella brightly shines at magnitude zero and is the sixth brightest star in the night sky. Auriga is Latin meaning “charioteer” and consists of 657 square degrees of sky ranking it 21st in size. Capella is a yellow-white sun located 43 light years away and possesses an extremely close companion which has been separated by the Hubble Space Telescope.

Almaaz (epsilon Aurigae) is a third magnitude star with a spectral class of F0 and is a supergiant measuring 135 times the diameter of the Sun. This star is an eclipsing binary system that ranges between magnitude 2.9 and 3.9. Well that is the good news, the bad news is it eclipses for a duration of 20 months every 27 years with the last minimum occurred from 2009 to 2011. Almaaz is located 2,000 light years from us.

Three lovely open clusters gather in the lower section of Auriga. The Milky Way also runs through this section and lends a perfect back drop for photography. M37, M36 and M38 are lined up nicely and are a treat in any optical instrument. Of the three, M37 is the richest open cluster glowing at magnitude 6.2 and is nick named “the salt and pepper cluster”. It has an even distribution of suns and located 4,400 light years away. M36 and M38 are about the same distance and but has less stars. M38 is a magnitude fainter. Including the Flaming Star Nebula when photographing there three clusters.

So far six exoplanets have been discovered within the boundaries of Auriga. They orbit the stars catalogued: HD 43691, WASP-12, HAT-P-9, HD 49674 and HD 45350.  However the brightest star of the group that can be seen with binoculars is HD 40979. Located near the star Menkalinan, this magnitude 6.7 star is the parent sun to a planet 3.3 times the mass of Jupiter. It was discovered in 2002 and has an orbital period of 263 days. HD 40979 is located 108 light years from us.

As we approach the spring equinox on March 20 at 6:29 a.m. eastern, we have the last opportunity to witness and image the zodiacal light in the west an hour after sunset. March 14 starts the two week window when moonlight will not interfere with seeing this narrow band of light. The zodiacal light is simply left over interplanetary dust from the creation of the solar system. Spring and fall equinox allow us to see this dust reflecting sunlight the western show forming a slanted wedge of light angled to the ten o’clock position that ends below the Pleiades. Dark skies are a must.

Venus is really putting on a great show in the western sky. As it moves between the Earth and Sun, it is now sporting a fantastic crescent. On March 1st the illuminated phase is down to 18% and shrinks to a mere 8% by the 10th. Use caution after this date as Venus is getting closer to the Sun’s glare and dangerous to locate. Jupiter is well up in the east by 10 p.m. and dominates all night long. Be sure to follow the Galilean moons by referring to the RASC Observer’s Handbook 2017 page 232. Saturn is now up by 4 a.m.

The Messier Marathon is the challenge of seeing all 110 Messier objects in a single night. This is scheduled for the latter part of the March when dusk and dawn will not interfere when searching M74 and M30. With the new moon slated for the 27, the two weekends at your disposal are March 25/26 and April 1/2 with the first choice being best. The secret is to follow the list of Messier objects to maximize your search time. This month’s full Maple Syrup Moon occurs on the 12th.

Until next month, clear skies everyone.

Gary Boyle

Twitter: @astroeducator

Author: Gary BoyleeNews date: Wednesday, March 1, 2017Category: Northern SkiesFile:  2017 - 03 chart 1.png 2017 - 03 chart 2.jpgTweet::  Pages

The Sky this Month - February 2017

Hunting The Hare

Nestled below Orion is a lazy cross of stars. This is Lepus the Hare. A some what small constellation that measures only 290 square degrees of sky, making it 51st in over all size. The Hare seems to be chased by Orion’s two hunting dogs, named Sirius and Procyon. Lepus does have the distinction of being the first constellation catalogued by Ptolemy in the second century BC. The bright star at the centre of the asterism is named Arneb, from the Arabic meaning “the Hare”. The alpha star is about 1,300 light years away and shines at magnitude 2.5. It is a spectral class F0 supergiant that is 13,000 times brighter than the Sun and 75 times its diameter. If placed in our solar system Arneb would reach the orbit of Mercury.

A few choice objects inhabit Lepus such as the large galaxy NGC 1744. Measuring 7.5 by 3.5 arc minutes, this barred spiral galaxy is located 34 million light years away. Although it has a magnitude value of 11.1, its face-on orientation makes this galaxy a bit difficult to spot. It can be found at the bottom right side of the constellation and about four degrees south of Epsilon Leporis.

Moving east we come across the only Messier object associated with Lepus. M79 is a highly resolved globular cluster that lies 42,000 light years from us and 118 light years wide. By galactic standards, this object is far from home as most globular clusters tend to reside close to the centre of the Milky Way and not 60,000 light years away. M79 measures 9.3 arc minutes wide or about a third the size of the full moon. At magnitude 7.7, it is an easy binocular object.

Located at the top of Lepus is IC418. Dubbed the Spirograph Nebula because of its similar design from the mid 1960’s drawing toy, its intricate structure is still a puzzle to scientists. This planetary nebula is located some 2,000 light years away and measures about a third of a light year across.

For a two week period commencing Feb 13, head out to dark skies to view and photograph the zodiacal lights in the west. This glow is left over interplanetary dust from the early creation of the solar system. Best times to see this band is close to the spring and fall equinox. The zodiacal lights are angled along the ecliptic (zodiac) from the horizon to a bit south of the Pleiades. If weather is not in your favour, you will also have a two week window in March.

The two western planets are now separating with Venus is starting pull away from Mars and sinking down to the west. At the beginning of the month Venus is only 39% lit as seen through a telescope and by month’s end, its large but thin crescent will be a mere 15% lit. It will be at its brightest on the 17th at magnitude -4.34.

Jupiter now rises around midnight local time with the star Spica a few degrees south of the planet. By comparison, Jupiter is 42 light minutes away while the star is 250 light years from us. Saturn has now crossed into the morning sky and is seen rising from the south east by 5 a.m. local time to the left of Scorpius.

There will be a penumbral lunar eclipse on February 10 from 22:32 UT to 2:55 UT on the morning of the 11th. The full Snow Moon will slide into the outer portion of the Earth’s shadow. Unlike the dramatic colour change of a total lunar eclipse when the Moon turns orange, the penumbral event is hardly noticeable. Two weeks later on the 26, there will be an annular solar eclipse seen from the lower portion of South America, the Atlantic Ocean and the western part of Africa.

Until next month, clear skies everyone.

Gary Boyle

Twitter: @astroeducator

Author: Gary BoyleeNews date: Wednesday, February 1, 2017Category: Northern SkiesFile:  Lepus.pngTweet::  Pages