April 27, 2016: 5th Moon of Jupiter? 42nd Messier; No-Detail Mars; and A New Season of Outreach

A couple of days after NEAF, the skies cleared for most of a week.  Pretty nice!  And about friggin’ time!  (This is because from November through March, the weather here in New York just simply sucks for observing.)

My first night out, Jupiter was riding nice and high and gorgeous as ever.  But, but . . . it had 5 moons!!!  What-what-what?  Galileo didn’t have 5 moons named after him.  Four of them were in a nice straight line, but the 5th one, all the way at the end, was offset, a little higher than the rest.  In fact, it looked exactly like this:

Five moons
Five Galilean moons?  (Photo credit:  Brian Wheeler)

It was tough to figure out which moon was which here, but a check of Stellarium shows that a 7th magnitude star by the name of HIP 54057 just so happened to line up in formation with the 4 real Galilean moons.  It turns out that Ganymede was the high outlier, while the star just fell perfectly into line with the other moons.  The star is the close one on the bottom left.

This was definitely a relatively unusual occurrence.  First, that the star would be so perfectly in line with the 4 moons.  But probably just as important, that it wouldn’t be overwhelmed by Jupiter’s glare.  Jupiter is almost negative second magnitude, and it overwhelms whatever’s in its vicinity.  In fact, a couple of the Galilean moons, Io and Ganymede, are bright enough at 5th magnitude, that if Jupiter wasn’t washing them out, they would just be visible as naked eye objects themselves.  In the year and a half I’ve been observing Jupiter since buying this scope (and I observe Jupiter pretty much every chance I get), I’ve never seen a star line up as perfectly as this one did.

I scored another Messier object, M93, my forty-second, one I had overlooked.  M93 is an open cluster in Puppis, or, as I like to refer to it, Canis Major West.  The cluster is near, but south of, two other open clusters in Puppis, M46 and M47.  To be honest, it’s not much to look at.  I’m not sure how I never got around to looking at it all this time, but there it was in Stellarium, so now I’m able to check it off the list.

The weather held for a nice long while, and I was able to get another shot at Mars, my first one in over two months, when I observed it just past one degree above the horizon.  Mars is fast approaching its biannual opposition when it will be closest to the earth, and therefore at its largest in the sky.  These are the windows when spacecraft are launched towards Mars, so that the probes can arrive there with the shortest flight times.  For most of the 26 months between oppositions, when Mars isn’t at its largest, it’s very small, between only about 3 to 5 arcseconds across.  By way of comparison, Jupiter is always between about 40 and 45 arcseconds across, so it’s positively huge.

Because Mars’ orbit is so eccentric (meaning it’s more of an ellipse than a perfect circle), there are times in its orbit when even though it’s at its closest for that opposition, it can be further from us, and other times when it’s much closer to us.  This opposition on May 22 is a halfway decent one; Mars will approach to within only 47 million miles and be 18 arcseconds across, almost half the size of Jupiter.  That closest distance can be much further; for the 2012 opposition it was 63 million miles, and Mars was just 14 arcseconds wide.  The next opposition after this one will be in July 2018, when Mars will be less than 36 million miles away and it’ll be positively huge at 24 arcseconds.  The idea, of course, is that as Mars gets closer, and bigger, details on its surface can be seen, including one of the polar caps and possibly some of the larger surface contrast features, like Syrtis Major.

Unfortunately, both this opposition and the next one will not be very good for observers in the Northern Hemisphere.  Mars is currently in and will remain in a part of the ecliptic (the path through the sky that the planets travel in) that doesn’t rise very far above the horizon.  From New York, next month’s opposition will be when Mars is at a maximum of 28 degrees above the horizon, still relatively down in the atmospheric murk that obscures fine detail.  The next opposition after that in 2018 will be even worse at only 24 degrees maximum.  It won’t be until 2020 when Mars gets to a lovely 55 degrees above the horizon at a still very respectable 22 arcseconds across.  That opposition will be an excellent opportunity to really see some nice detail on the surface of Mars.

Unfortunately, so far, this one hasn’t been such a great opportunity – yet.  Mars is still rising relatively late in the evening.  My sojourn a couple of nights ago at 1:30 am to catch Mars at greater than 20 degrees above the horizon was a bust.  Not only couldn’t I see any detail, even with Mars already at 15 arcseconds in width, but the clouds finally rolled in just past 2am, so I didn’t even get a good chance to observe after my telescope had had a chance to cooldown.  Well, there’s still a month to go until opposition, and a few weeks after that too, when Mars is still relatively close and big, so I should get a few more chances.


Spring is here, and the outreach season began again with a nice treat for the astronomy fans out there:  two consecutive shadow transits of Jupiter.  First Io would start its transit while the sun was still up.  Because I could use the moon to do a “Solar System Alignment”, the scope was able to put me right on Jupiter, even in the daylight – pretty neat!  I couldn’t initially see the Io transit, though, because of a lack of contrast in the still very blue sky, but the equatorial bands were plenty visible enough.

Passersby who took a look during the day were disbelieving what they’re seeing.  They thought that since they couldn’t see Jupiter in the daylight with their own eyes, it wasn’t possible for my scope to do it either.  Well, who are they gonna believe, me or their own eyes?  The answer is the same argument as to how to combat light pollution in general – increased aperture wins.  With the sun as the ultimate light pollution source, my 5-inch Mak was still capable of overpowering all that LP and allowed me to see negative second magnitude Jupiter even in broad daylight.  So the old adage that larger aperture scopes simply collect more light pollution is simply incorrect.  They punch through it.

Right after twilight, I got a final view for the season of the lovely Pleiades in my ST-80 as they were setting over a building in the west, and, a little bit later, a final look at the Orion Nebula as well.  The latter was through the C8 scope of the AAA coordinator for the Carl Schurz Park outreach sessions, a nice fellow named Bruce.

Meanwhile, a young man brought out his brand new baby, a Celestron 114 LCM, and asked us if we could show him how to use it.  We did, but just barely.  He didn’t have batteries for either the motor or for the red-dot finder, so the scope couldn’t move much on the mount.  I literally had to lift and point the entire thing at the 8-day-old moon manually as best I could by dead reckoning.  Fortunately, this is made easier by the wide circle of bright moonglow in the sky around the moon.  As you get closer, things get brighter until you finally catch the moon in the eyepiece.  When he got his first look at the moon through his very own scope, his grin was about a mile wide.  Another satisfied customer!

I also gave some advice to a nice young woman who was looking to buy her first scope.  I generally try not to recommend my own scope, the Mak, both due to my own huge personal bias in favor of it, and due to people generally wanting to buy something cheaper for their first scope, so I generally end up recommending the Meade Infinity 102 to people.  That’s a nice 4-inch manually operated refractor that comes with 3 Kellner EPs and a Barlow, on a decent mount, all for just over $200.  I went through the various alternatives present:  as I mentioned, Bruce had an 8″ SCT, Jason had a very cute 4.5″ Orion dob that he had just restored, but that you had to get down low and sit on a tiny step to use, and Jorge and Giuseppe both had 4-inch refractors.  However, she understood the advantages of the Mak over these other scopes, not only the computerized goto ability to find things in the light-polluted city, but most especially, the Mak’s ability to observe while seated because of its short tube.  Ah, a woman after my own heart!

Finally we were able to see the Europa transit later in the evening, but only just.  Although I had my scope on my homemade anti-vibration pads, and the seeing was pretty good, Carl Schurz Park is situated directly above the FDR highway.  I can’t help but think that the vibrations were still enough to mess up the view somewhat.  But see it we did, a little 2000 mile wide shadow from 432 million miles away.  Great stuff!


One thought on “April 27, 2016: 5th Moon of Jupiter? 42nd Messier; No-Detail Mars; and A New Season of Outreach

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