While the Geminid meteor shower of
mid-December reigns supreme as the northern hemisphere’s most productive
display of shooting stars, August’s Perseids, coming in a close second, are the most widely observed meteor shower of
the year. Why? Warm temperatures find families spending more time outdoors
during the summer season enjoying cookouts, camping, or any other assortment of
late evening activities. Normally 60+ green, red or orange Perseids can be
observed per hour during peak activity. Unfortunately, for 2019 a waxing
gibbous Moon (Full on the 15th) will severely hamper observing this
meteor shower which peaks on the night of August 12-13.
However, while moonlight will wash out all
but the brightest meteors before midnight on the night of the 12th,
once the Moon sets around 3:48 a.m. that will leave just over an hour of dark
sky observing time before dawn’s early light begins to brighten the sky.
Somewhat helpful is the fact that Perseus, the constellation from where the
meteors appear to radiate (known as the radiant point), is completely opposite
the sky from the Moon. This circumstance could help extend your window of
opportunity to an hour or two before the Moon sets! Hey, I’m trying my best to
be optimistic here!!
Just around midnight Perseus can be found
about halfway above the northeast horizon. To locate Perseus, use the
constellation Cassiopeia as your guide. This star pattern looks like a sideways
capital “M” or “W.”
The Perseid meteors are about the size of a
thumb nail as they plunge into Earth’s atmosphere at 134,222 miles per hour (37
miles per second) and disintegrate. You know you’ve seen a Perseid if you can
trace the path of that meteor back to the radiant point. If peak night is cloudy
you can try your luck on the nights before and after. The Moon will still be an
issue however and the number of potential meteors will also be much lower as
the Earth will no longer be passing through the denser regions of the meteor
I hope the weather gods have provided a few
clear nights since my Jupiter observing guide appeared last month. I finally
observed Jupiter at a late June star party Skyscrapers members conducted for
the Jesse Smith Memorial Library in Harrisville on June 28. The four Galilean
moons were easily visible in all the telescopes, as were Jupiter’s striking
banded cloud tops. Regrettably the Great Red Spot was not visible that night,
and my attempts to observe it since my last column have been thwarted for one
reason or another. Fortunately, we have several more months to glimpse this
perhaps dwindling storm.
I’m sure some of you couldn’t resist an
early look at Saturn, even if you had to wait much later in the evening for
this beautiful ringed-planet to rise high enough into the sky to clear summer
horizon haze. Perhaps sky conditions permitted you to obtain marginal views
despite the planet’s low altitude above the horizon within a couple of hours
after sunset. Now that another month has passed, Saturn will have risen much
higher into the southeast sky, thereby allowing for more favorable views. As
promised at the end of July’s column, here is a brief observing guide to Saturn
(our solar system’s most stunning planet.)
Simply mention the planet Saturn and immediately
any child or adult will visualize a world surrounded by a system of rings. And
if it weren’t for Saturn’s rings the disk of the planet could be considered boring,
as its clouds are not as prominently colored as those are of Jupiter. With the
exception of Titan, Saturn’s largest moon, its other brighter moons are not as
bright as Jupiter’s either. The beauty of Saturn lies solely in its rings.
Back on July 9 Saturn was at opposition,
rising as the sun set. This event also signaled Saturn’s closest approach to
the Earth for 2019—839,641,920 miles. By August 1 this distance has grown to 847,023,600
miles as the Earth pulls out ahead of Saturn in our respective orbits.
Regardless of this ever-increasing distance from Earth during the remainder of
our Saturn observing season, views of the planet never disappoint the casual
stargazer or amateur astronomer.
When August begins, Saturn will be about 20 degrees above the southeast horizon at 9:00 p.m., nestled among the stars to the left of Sagittarius’ “teapot handle” asterism.
Saturn will continue to rise higher into the sky along a low arc until it reaches your north/south meridian around 11:00 p.m. At that time Saturn will be only 26 degrees above your southern horizon. For northern hemisphere observers summertime planetary observing is far from ideal because the ecliptic, the apparent path of the Sun and plane of the solar system, traces out a low arc across the sky during summertime nights. And since the planets can never stray from the ecliptic, they also will traverse this low arc.
Regardless, clear and turbulent-free atmospheric conditions can provide
spectacular views of the Saturnian system. When you first acquire Saturn with a telescope, its
rings will initially take your breath away. They are really an impressive spectacle
to behold. The ring system is currently tilted 24 degrees toward the
Earth providing us a view of the north face of the ring plane. With the rings
still being wide open (they were at their maximum tilt of 27 degrees two years
ago), this configuration allows much detail to be seen. You’ll understand what
I mean as soon as you gaze at this splendid sight.
It is really amazing that Saturn’s rings
are visible at all, considering the planet’s great distance from the Earth and
the fact that the main A, B and C rings are only about 32 feet thick. Whereas other
portions of the ring system are up to a couple of miles thick. The rings are
composed of irregularly shaped dirty snowballs (99 percent water ice with some
rocky material), ranging in size from grains of dust to pebbles. There are also
some “boulders” as large as 30 feet across. These ring particles all orbit
Saturn along the planet’s equatorial plane. Look for gaps within the ring system.
You shouldn’t have any difficulty seeing the
gap between the primary “A” (outer) and “B” (inner) rings, called the Cassini
Division. This region is only 2,175 miles wide. In comparison, the width of the
“A” ring is 9,321 miles and the “B” ring is around 16,032 miles across.
Saturn’s rings are slowly de-orbiting and all will eventually “rain” down onto
his cloud tops in 50 to 100 million years or so and cease to exist. So, you’ve
got plenty of time to enjoy the view.
This configuration of the rings provides a
stunning 3-D effect of the Saturnian system, and after opposition as our
viewing angle changes a keen-eyed observer can look for the shadow of the rings
upon Saturn’s cloud tops as well as the shadow of Saturn onto its rings.
And finally, although Saturn has 62
confirmed moons (at last count), they are not as bright as those of Jupiter. One
can also detect up to eight of Saturn’s brightest moons in a dark moonless sky
with the telescopes available locally. Readily apparent will be Titan, Saturn’s
largest moon (and larger than the planet Mercury), followed in order by size and brightness by Rhea, Iapetus, Dione, Tethys, Enceladus, Mimas and Hyperion
While a small two-inch telescope will reveal the beauty of Saturn, search out larger instruments available throughout Rhode Island to explore this exquisite ringed world in splendid detail. Seagrave Memorial Observatory in North Scituate is open every clear Saturday night for observing. Ladd Observatory in Providence is open every clear Tuesday. The Margaret M. Jacoby Observatory at the CCRI Knight Campus in Warwick is open every clear Wednesday night. Also consider visiting Frosty Drew Observatory in Charlestown on every clear Friday night. Please visit the respective websites for details. These observing sessions are free and open to the public.
a few months have passed since the local observatories have had the opportunity
to provide detailed images of some of our planetary companions in the solar
system. When weather conditions have allowed, the Moon has been a good
substitute. When the Moon has not been available, telescope operators have
turned to double stars and faint fuzzies like star clusters, galaxies and
nebulae. However, these celestial objects don’t often elicit the wow factor
that planetary viewing can do. Add some high thin haze, atmospheric turbulence,
a little bit of moisture and light pollution, and it has been a challenge to
provide decent views of the heavens. Our observing opportunities have now greatly
amateur astronomers have been observing Jupiter and Saturn during hours when
most people are in REM dreamland, from now through November telescopes
throughout Rhode Island will focus on exquisite views of these two gas giant
worlds and all their glory. All I can say is, “It’s about time!!” This month’s
column will provide a brief observing guide to Jupiter. Next month I will feature
on June 10 Jupiter reached opposition. That means it rose as the Sun was
setting. This date was also the date of Jupiter’s closest approach to the Earth
for this year—about 397,850,855 miles. By July 1 this distance will have
increased to 403,576,313 miles as the Earth pulls out ahead of Jupiter in our
respective orbits. Fortunately, views of the Jovian system do not suffer dramatically from
rapidly increasing distance.
we approach the Summer Solstice in the northern hemisphere, this year on June
21 at 11:54 a.m. EDT (Eastern Daylight Time), here in Rhode Island many folks
revel in the extra daylight hours, especially in the evening. Astronomers are
not among those individuals because our skies do not get fully dark until about
10 p.m., and dawn’s early light starts around 4 a.m. That leaves little time to
explore the universe with telescopes and cameras to capture the beauty of the
heavens. Then as the summer months continue, we must contend with high humidity
and pesky mosquitoes.
However, there are a couple of planets we will welcome back to the evening sky over the course of this summer. They are Jupiter and Saturn. These distant worlds reveal much detail in the telescopes at the local observatories.
It’s challenging to explain to someone that you
spent a below-freezing December night sitting on your back porch bundled up in
a sleeping bag on a lounge chair just to watch a few meteors blaze across the
sky. Why? Because sometimes even I question why I choose to do so. A few months
back the Geminid meteor shower did not perform well around here, at least not
when I decided to observe it. After about an hour and a half I counted less
than a dozen meteors, and not all of them were Geminids. Only a couple of them
were bright enough to elicit a wow, though not loud enough to wake my neighbors!
That’s the way it is with meteor showers.
Sometimes you’re in the right place at the right time to see the meteors to best
advantage. Other times you are not. It can be frustrating when the latter
occurs, especially when the weather conspires against you. Still, after all my
decades of stargazing I never tire of watching for meteors to fall from the
The early days of May present us with warmer
weather prospects to enjoy a somewhat “meteor-ocre” display of shooting stars.
During the pre-dawn hours of May 5 and 6, the Earth will be sweeping through a
stream of particles shed by Halley’s
Comet long ago. (Either morning will be a fine time to observe since the Eta
Aquarids do not have a sharp peak. The meteors comprising this meteor shower enter
the Earth’s upper atmosphere head-on at 41 miles per second. While the Moon will
not interfere with observing this shooting star display this year (New Moon is
on the 4th), one can expect to see no more than 10-15 swift and
yellow shooting stars per hour from Southern New England. Why? The Eta
Aquarids, are best observed from the southern hemisphere.