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The Sky This Month Apr-May 2016

Submitted by hotair@compute… on 25 April 2016

It is a busy time! The big next event is the Transit of Mercury. But Mars is in the picture, nearing opposition. There are many wonderful deep sky objects (mostly in Virgo) to see this time of year. Also, there are many things going on in low-Earth orbit as well as on the ground.

Blake Nancarrow delivered the following The Sky This Month presentation at the 27 April 2016 Recreational Astronomy Night Meeting at the North York Memorial Community Hall. He prepared his usual month-at-a-glance calendar covering the final week of April and nearly all of May 2016. You may view or download and print the colour calendar PDF file (345 KB).

All photos copyright the respective owners.

Observing Lists

The suggested targets for this TSTM have been formatted in observing lists for popular astronomy software.

Note: The SkySafari list does not include the faint quasar B2 1225+317. Use the nearby star TYC 2528-563-1 (aka PPM 76500) instead.

Note: Both files stored on Blake's web site under the Computer Ease domain.

Close to Home…

There are lots of events happening in the province of Ontario. We're winding down our winter meeting programme which means transitioning from meet-ups every two weeks to one a month. For this The Sky This Month period, there are three RASC meetings, including the one on Apr 27, the Speakers Night on May 11, and then another RAN meeting on May 25 (oh, Towel Day!). The RASC Toronto Centre solar, dark sky, and city observing sessions are also noted on the PDF monthly calendar.

Apr 30, the coming weekend, is the next RASC TC astrophotography special interest group gathering at the David Dunlap Observatory (DDO). These workshops are proving very popular. We're planning more later this summer at Carr Astronomical Observatory (CAO). That will be especially interesting: learn in the day then apply in the dark skies of the Blue Mountains.

Speaking of the CAO, the first official supervised weekend begins May 7. And that will fold into the Transit of Mercury event on Monday... Wishing for clear skies!

May 9 is the start of International Astronomy Week with May 14 as Astronomy Day. Look for activities are the Ontario Science Centre (OSC) and around the Greater Toronto Area (GTA). It's a great time to talk about and learn more about astronomy and cosmology.

May 9, again, is the big day with the transit of the inner-most planet across the face of the Sun. Events are planned around the GTA, along with Richmond Hill, and the Blue Mountains.

May 10 is the first date (of three) for the weekly First Light programme to help new members. It's happening, as usual, at the DDO. Get oriented to the Toronto Centre!

The big national event is taking place in the Forest City, aka London, Ontario. The General Assembly of the Royal Astronomical Society of Canada starts May 19. In conjunction with the GA is the AstroCATS telescope gear trade show. And, new this year, the Canadian Astro Photography Schools (CAPS).


We Built This

Now, a bit of flag waving...

Image by NASA.

  • The year Chris Hadfield conducted the first space walk (the first Canadian spacewalk!) on end of Canadarm2: 2001.
  • Shuttle mission number when Canadarm2 was installed on International Space Station: 100.
  • Anniversary date of Canadarm2 install in April: 19.
  • Length of Canadarm2 in metres: 17.
  • Years on orbit: 15.
  • Currency note emblazoned with Canadarm: fiver.
  • Years previous, that arm grabbed the first private spacecraft (Space X Dragon): 4.
  • Contribution to the low-Earth orbit operations: priceless.

It is pretty remarkable when you think about it what we accomplished. The ISS could not have been built without a powerful and capable arm, boom, transport system, and grapple. The continuing operations are made possible by Canada's robotics skill and knowledge. See the article at the Canadian Space Agency for more information and cool photos.

It is also very interesting at the moment on the space outpost: there are two private vessels docked (a first); the Bigelow Expandable Module (BEAM) is installed, ready for inflation. And there are more mice on board!

Unfortunately, we are out of phase for evening flyovers of the ISS. Morning passes should resume in a couple of weeks. Use Heaven's Above to predict events.


Space Telescopes

Early this week, on Apr 25, we noted the anniversary of the Hubble Space Telescope deployment (in 1990). Happy birthday! It's been an amazing 26 years...

It's alive! The Kepler space telescope is working again. It was launched in 2009 so to scan a particular area of the sky in Cygnus-Lyra region. It looked for transits, that is, instances when a planet moved between the telescope and a star (not unlike what we’ll do in a couple of weeks!). It watched for brief dimming in the light from stars. For four years it searched for Earth-like planets and successfully found thousands. The Kepler was repurposed recently, in a clever way, taking into account that its gyroscopes are not working correctly.

There was some sort of glitch but the operational team recovered and the space telescope, with large sensor, is continuing its K2 mission. You may be interested to know that the K2 campaigns are entirely community driven! Visit the Kepler site for more information. The K2 mission is looking in other parts of the galaxy now.


Go Deep

You can explore the Milky Way galaxy from a dark site. The new Moon is May 6. It is interesting how, in May, the Milky Way rises around us. Well, that's a bit of a cheat. Around midnight, looking east, you can watch our galaxy rise up over the eastern horizon, and for a long time, appear parallel to it. It gives a very strong sense of a ring, tilting up.

Screen snapshot from Stellarium. May 6, 2016, looking south at midnight.

There are many wonderful double star and multi-star systems this time of year. Check out colourful 54 Leonis and the brilliant stars of Cor Caroli in Canes Venatici.

There are also some fun planetary nebula to try for this season including the Cat's Eye's and Turtle.

Like open clusters and their jewel-like appearnace? It's a tad late in the season but have another go at the Beehive. Messier 67 is also good now.

A couple of globular clusters, tight balls of stars, are well placed: M3 and M5. They will whet our appetite for the big and bright summer globs.

There are a couple of comets to view and/or image. C/2014 S2 (PANSTARRS) in UMa is magnitude or brightness value 10.5, about 1.6 minutes-of-arc in size, and 2.4 astronomical units (Earth-Sun distances) away. Comet 252P/LINEAR is in Oph, mag 8.8, 18.0', but close at 0.3 AU. Visit Yoshida's site for up-to-date comet information.

Ready for a challenge? Have you chased down any quasars? Star-like quasars can be viewed in amateur gear, believe it or not. 3C 273.0 is a relatively easy one, in Virgo, at magnitude 13. It is 1.9 giga-light-years away. Wow. Impressive. And if you have access to a big 'scope, a really big 'scope, then try for B2 1225+317 in CVn. It's dim at mag 16. But it's worth it. It's 9.1 Gly away! Incredible.



Galaxies abound. May is a excellent time to explore the super cluster of galaxies near Virgo. Some Messier targets hover below the belly of the lion, Leo. Corona Borealis harbours some distant galactic targets. And, to the north, up high, above the Big Bear, are Messiers 81 and 82.

Tag these galaxies on moonless nights: the Cocoon, the Whale, the Needle (NGC 4565), the Black Eye, the Lost, and the Sombrero. The challenging low-lying Messier in Hydra, M83, is sometimes the last one people add to their certificate checklist. This is the time to get it!


Dynamic Stars

There are a number of interesting (and intensely coloured) variable stars to peruse. Variable stars and fast-moving binaries remind us that the Universe is not constant. Everything's moving, shifting, changing, aging.

Some very interesting stars to examine, ideally at lower power, are red stars. La Superba in CVn is an intense colour. UX Draconis is a fantastic specimen easily mimicking a hot ember in a firepit.

Light curve from AAVSO.

The Blaze Star in Corona Borealis (aka T CrB) has been getting some attention lately. The recurrent nova has been brightening and turning more blue. See the observing campaigns page at the American Association of Variable Star Observers (AAVSO) site.

Check out Alula Australis in the back feet of Ursa Major. This rapidly moving double star is best viewed in the spring. This pair, like other fast binaries, changes over the years. The angle of the two stars, and the distance between, is something you can watch for and return to year after year.


Jupiter Events

Jupiter is leaving our night skies so enjoy it while you can. The bright “extra” star in Leo. It is never dull. You might record yet another comet impact!

Image by Rick Foster. Used with permission.

The PDF monthly calendar shows "Jupiter events." These are times when there are 2 or 3 interesting things happening at the King of the planets. For example, it could be that a moon is transitting over the planet, with its shadow trailing behind, all while the Great Red Spot is visible.

May is Mars Month

Mercury will get a lot of attention this month but it is for one day! Mars will provide many evenings of entertainment! It rises around midnight. It is pulling away from Saturn. It is near or in the constellation Scorpius, not far from a rival, orange Antares.

Mars is drawing closer to the Earth. It will grow larger that 18 arc-seconds heading toward opposition on May 22. Orbital mechanics between the 3rd and 4th planets mean that approximately every 22 months, we get close. But because the Red Planet has a very elliptical orbit, some years are better than others. This May will be the best Mars show in a decade.

Image from NASA.

When Mars is close, you'll see an intense orange colour with your eyes unmagnified. In a telescope you should be able to see surface features, light and dark regions, the polar ice cap, and, if you're lucky, clouds and dust storms. This is a great time to image the red world.

When Mars is near to the Earth, it is also a good time to try to spot its two tiny moons, Deimos and Phobos. But this is very challenging. The moons are around magnitude 11 while the planet is -1! That incredible difference means that the bright glare of the host planet will likely prevent direct viewing of the faint moons. One trick to overcome this is to use an occulting eyepiece. You could try making one. See the old Sky & Telescope article for instructions. Another trick is to deliberately look for the moons when they are at maximum elongation. That's when a moon is at a 90 degree angle to our line of sight. It will appear furthest away from the planet then. Every little bit helps.


The elongations of Phobos and Deimos are brief. In particular, Phobos orbits Mars fast, every 16 hours! Use your planetarium software (like Stellarium) to examine the motion up close.

By the way, there are other oppositions this month, periods when a solar system object is opposite the Earth from the Sun (i.e. the Sun is behind us). Juno, asteroid 3, is April 27. Iris, asteroid 7, is on May 29. Saturn will be at opposition soon, early June.

Conjunctions occur when objects are very close to one another. When an inner planet is on far side of Sun (er, opposite), that is superior conjunction; inferior, it's in-line with Sun and between us. Of course, there's a big one coming up…


Transit of a Star by a Small Planet

SAFETY FIRST! Ensure proper solar filters are used with telescopic and binocular equipment. Injury and damage to eyes without proper protection can be instantenous and irreversible.

Here is the time-line for the Transit of Mercury event on Monday, May 9, 2016. These times will work for residents of Ontario near the Greater Toronto Area.

6:50 AM - Sun rise
7:13 - first contact, planet first touches the disc of Sun
7:16 - second contact, planet entirely inside disc of Sun
9:38 - Moon rise
12:48 PM - Venus at meridian
1:16 - Sun (and Mercury) at meridian
2:38 - third contact, about to leave Sun's disc
2:41 - fourth contact, done

If we're lucky, there will be some interesting sunspots and solar flares too!

There are "star parties" planned all around, at the DDO, the OSC, and the CAO.

Hopefully it will be clear. Mercury transits are not as rare as Venus: the next event is Nov 2019. In fact there are six more visible in Ontario before 2062.

Be safe!


It's a Wrap

To review, your highlights for Apr-May 2016 are:


30 – astrophoto workshop


2 – dark sky observing window opens
5 - eta Aquarid meteor shower peak
6 – new Moon
9 – transit of Mercury
9-14 – Astronomy Week
13 – Lunar X
16 – city observing window opens
19 – fun in London
22 – opposition of Mars

with Jupiter “events” galore and many possible opportunities to see the moons of Mars!

Hot Off the Press!

These recent "breaking" events are not shown on the PDF calendar...

May 2: Another transit! But a special one... Morning. ISS Double Solar Transit (visible from a site [near Newmarket] 84 km away). The International Space Station crosses the disk of Sun twice seen from the same location.

May 3: Space X launch of the Falcon 9 rocket. With a planned at-sea recovery of stage 1 rocket. Tentative.

Be seeing you. Contact Blake Nancarrow (astronomy at computer-ease dot com) for errors, omissions, questions.