An old Standby

 

In these days of Covid-19, getting together with others to have a look at the night sky is an exercise of don'ts: don't get too close to each other, don't touch or look through the telescope, don't come without a mask, etc. On-line meetings are substituting for the in-person ones. My wife and I are practicing voluntary self-isolation (we are old enough to make this necessary). That means that I'm confined to observing the sky from our home. 

 

We live in a highly light-polluted and horizon-limited area. The smoke from the wildfires in the U.S. has added to the lack of visibility of the stars. There were just a couple of acceptable evenings which led me to look for one of my favorite objects in the sky: The Whirlpool Galaxy not far from the end of the Big Dipper's handle. In a dark sky, M51 can be seen in larger binoculars as a small, diffuse patch of light.

I used my 15x50 Canon stabilized binoculars to try and see it. I did not detect it at all. The gray sky here made it an impossibility.  In earlier years M51 was easy to see from our house; high-rises, new and under construction, now limit our horizon and add much light pollution.

I decided to get my "M51 fix" by posting an image I took a couple of years ago by connecting my computer to Slooh.com to use one of their remotely accessible telescopes and take a picture; below is the result:

 

 Messier 51 

Image taken through the wide-field, 17 inch remote-control Slooh.com telescope located at the Institute of Astrophysics of the Canary Islands. 

 Some history (from Wikipedia):

"What later became known as the Whirlpool Galaxy was discovered on October 13, 1773, by Charles Messier while hunting for objects that could confuse comet hunters, and was designated in Messier's catalogue as M51. Its companion galaxy, NGC 5195, was discovered in 1781 by Pierre Méchain, although it was not known whether it was interacting or merely another galaxy passing at a distance. In 1845, William Parsons, 3rd Earl of Rosse, employing a 72-inch (1.8 m) reflecting telescope at Birr Castle, Ireland, found that the Whirlpool possessed a spiral structure, the first "nebula" to be known to have one. These "spiral nebulae" were not recognized as galaxies until Edwin Hubble was able to observe Cepheid variables in some of these spiral nebulae, which provided evidence that they were so far away that they must be entirely separate galaxies even though they are seen close together. The advent of radio astronomy and subsequent radio images of M51 unequivocally demonstrated that the Whirlpool and its companion galaxy are indeed interacting."

There are still some uncertainties regarding M 51. For instance, the distance of it is variously quoted as 31 million light years (NASA), Wikipedia says about 23 million, universetoday.com states 19 to 27 million light years. A location chart is shown above. A dark sky will allow for M 51 to be seen in 10x50 binoculars as a faint patch of light. An 8" (200mm) telescope will begin to show its spiral structure.

Messier 51 is circumpolar, so it is accessible for most of the year. At this time of year, the Big Dipper skirts the northern horizon through the night. M51 is therefore moves along above the northern horizon as well. Give it a try under a dark sky anyway. Its position will improve as we progress through winter and into next year.

At last, a naked-eye comet

After a fairly lengthy time of "comet starvation" we finally had an appearance of a comet which, while not super-bright, was visible to the naked eye. Comet Hale-Bopp in 1997 was the last one to be so visible. Using binoculars brought out a pretty impressive view of this "new" comet  (NEOWISE C/2020 F3), even in the light-polluted sky in our part of the city. Without the coved-19 pandemic in progress, the RASC would have held many public astronomy meetings; now this can only be approximated virtually (i.e. Zoom, and similar applications).

NEOWISE C/2020 F3 was discovered on March 27, 2020 by NASA's "Wide-field Infrared Survey Explorer" space telescope, which has been in orbit for about 11 years. You can see the source of the comet's name. This is a very productive telescope, which has discovered thousands of astronomical objects. Look up details in WIKIPEDIA under its name. 

At the time of discovery Neowise was a faint blob of magnitude 18, at twice the Earth's distance away from the sun. From position measurements made of Neowise C/2020 F3's orbital positions as it moved towards the Sun, a 4,400 year long orbit was calculated. By now, Neowise has been moving away from the Sun for some time, and is well past its closest approach to Earth on July 22. That means that its brightness is diminishing. The close approach to the Sun resulted in a change in the comet's orbital shape. The orbit is now longer and the comet has been recalculated to return in about 6700 years, or so (I won't wait for it).

Comet Neowise C2020 F3

This picture was taken on July 19, around 10:30 PDT with a Canon 60Da camera from our lawn next to the house. It's a 10-second exposure (f8, ISO 800). A slightly enhanced image, it is meant to show the comet better from our severely light-polluted area. It was easy to see with the naked eye. 

As the comet gets fainter, more and more telescope power will be needed to view it directly; photography, and the Hubble space telescope will be able to follow it for a longer time. By the third of August, the comet had faded to about magnitude 7, it was a faint hazy patch in my 10x50 binoculars, and I could not discern a tail. It was definitely no longer a naked-eye object. The Moon was almost full, and, in addition, the sky was somewhat hazy. Added to the light pollution in our area, this made viewing the comet less than ideal. 

 

Under similar conditions, Neowise was still visible in my 15x50 Canon stabilized binoculars in the evening (around 11pm PDT) of Aug. 9, between stars 70Virginis and 71Virginis. Directly looking at it showed a very faint, fuzzy, barely noticeable patch. Averted vision made it more readily perceived. The difficulty seeing it made for more fun to search for and trying to find it. Neowises's apparent motion is now relatively small, due to the relationship of the Earth's and the comet's respective orbits. It's like we were passed by a train, and we can see it down the track, getting smaller and smaller, but not moving sideways much.