Prime Time for Jupiter - Astronomy Insights A Digital Supplement to Astronomy Magazine
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Astronomy Insights A Digital Supplement to
Astronomy Magazine
© 2018 Kalmbach Media
Prime Time
for Jupiter
May 2019 • Astronomy.com
ASTROIMAGING
How to image
JUPITER The author took
this image of
Jupiter on March
5, 2015, at 12h54m
UT. It shows the
main equatorial
belts, the Great
Red Spot, and a
whole lot more
detail. ALL IMAGES:
CHRISTOPHER GO
Longtime photographer Christopher Go takes you step by step through
the process of imaging this gas giant.
B
esides Earth, Jupiter is the easiest planet to capture photographically. Its high surface
brightness and large angular diameter make detailed imaging accessible to any telescope
size. Even a small scope can resolve major features, like the Great Red Spot.
And now’s a great time to start shooting the gas giant because it lies high in the sky.
Professional astronomers at the Jet Propulsion Laboratory are requesting amateur images to sup-
port the Juno spacecraft, which will arrive at Jupiter in July.
As someone who has been imaging Jupiter for a decade, I’ve seen and tried a lot of equipment
and many processing techniques. Because I have “been there, done that,” the tips and techniques
I’ve developed can help you get started the right way. Take it slow, be sure you understand an idea
before you move to the next one, join an online imaging forum, ask lots of questions, and then
head out and shoot!
2 A ST R O N O M Y I N S I GH TS • MAY 2019
Lucky imaging
Currently, the method I and This image of the
most other amateurs use to giant planet, which
the author captured April
capture planets is called “lucky
9, 2015, at 10h59m UT,
imaging.” This uses a small shows great detail and
video camera attached to a accurate color. The Great
telescope. You later process the Red Spot at the left edge
is just starting to rotate
video with software that lets into view.
you stack frames. The program
has a routine to perform a check
on each frame. It then arranges If you use a mono-
chrome camera to
them in order of quality, letting shoot Jupiter, you have
you stack the best ones to pro- to capture exposures
duce a final image. through red, green, and
blue filters to produce a
color image.
Which camera?
One of the most common ques-
tions people ask is whether to
get a monochrome or color
camera. Color cameras are
easy to use and less expensive
overall because you don’t need
additional accessories like fil-
ters and filter wheels.
For beginners I always rec-
ommend a color camera. And I
have one other tip: When your
target planet lies below an alti-
tude of 70°, use an atmos-
pheric dispersion corrector to
offset the effects thicker layers
of air have on images.
For the highest-quality
images, amateur astronomers
should use monochrome cam-
eras because their pixels lie This necessity (I think it’s more You also may want to use a FOR THE
closer together than those in than an accessory) will make Barlow lens to increase image
color cameras. Monochrome your imaging easier. size, but I can’t tell you which HIGHEST-QUALITY
models also are more sensitive. one exactly. Its magnification IMAGES, AMATEUR
I use a Celestron Skyris Other accessories depends on the focal ratio of ASTRONOMERS
236M (pictured at lower right) If you select a monochrome the scope, the pixel size of the
for my monochrome imaging camera, you’ll need a filter camera, and your typical seeing
SHOULD USE
and the Celestron NexImage 5 wheel with a red, green, and conditions (how steady the air MONOCHROME
for my color images. blue (RGB) filter set to produce above your imaging site is). A CAMERAS
color images. Beyond standard variable Barlow, like the Astro-
Telescope color shots, I often use a meth- Physics Advanced Convertible
BECAUSE THEIR
and mount ane-band filter, an ultraviolet Barlow, allows flexibility. PIXELS LIE CLOSER
Almost any telescope can pro- filter, and an infrared filter. TOGETHER THAN
duce decent images of Jupiter. Each of these reveals different Imaging THOSE IN A COLOR
That said, use the largest aper- layers in Jupiter’s atmosphere. preparation
ture you can. Long-focal-length Note that the images you’ll get The most important step CAMERA.
telescopes are ideal for imag- through these filters will not be before you start to image is to
ing Jupiter because they offer as pleasing to the eye as your make sure that the telescope
higher magnifications. color shots. is at ambient temperature.
An optical tube is only as I also suggest a motorized A telescope warmer than its
good as its mount, however. As focuser. This accessory will surroundings will cause tube
much as it is up to you, choose allow fine focus, which is nec- currents that negatively affect
a sturdy polar-aligned mount. essary to get the best image. image quality. Also, avoid
imaging close to asphalt that’s
Christopher Go has produced images of Jupiter nearly every clear night been in the Sun all day, a hot
for a decade from Cebu, Philippines. Contact him at chris@cstoneind.com. roof, or other such structures.
W W W.ASTR ONOMY.CO M 3
The most important factor based on seeing is far more
in getting the best image is see- important than selecting a dark
ing. This means the site you site. After all, Jupiter usually
choose for capturing data is ranks as the fourth-brightest
critical. If possible, try to image object in the sky.
for three or four days straight
from several locations, then Image capture
pick the one with the highest- FireCapture is currently the
Gain and exposure time controls
quality air. Selecting a site standard image-capture soft-
ware. It supports different
camera manufacturers and
controls ASCOM (short for
AStronomy Common Object
Model) compliant mounts,
filter wheels, and focus-
ers. Also important to some
people: This software is free.
Here are some tips on using
FireCapture:
1. In “Capture Settings,”
Exposure time limit make sure that the file name
includes the object’s name, the
date, and the Universal Time.
Also, synchronize your com-
puter’s clock with an atomic
clock. When doing mono-
Histogram should be 80-90% by chrome imaging, make sure
adjusting gain and exposure time.
you indicate the filter used.
2. Use “Region of Interest”
(ROI) to reduce the capture
frame size. Using ROI creates
smaller files, increases the
maximum frame rate, and
makes processing faster. You
If you use the can do ROI by hold-pressing
“Wavelet” area in your mouse’s left button and
Registax carefully, your outlining the area around
images will dramatically
improve. Jupiter. Make sure you leave
some space for inaccuracies in
your mount’s drive.
FireCapture’s con-
trol screen offers
numerous options for
processing planetary
images.
Many planetary
imagers cut their
teeth on Registax, which
came onto the amateur
astronomy scene in May
2002.
4 A ST R O N O M Y I N S I GH TS
3. Set a time limit for cap-
turing Jupiter. This is the
“Limit” button on the control
panel of FireCapture. Because
of the planet’s fast rotation, Enter Universal Time as
there are constraints on how accurately as possible.
long an exposure can be for
Align wire frame to
each frame. For apertures image using F11.
smaller than 8 inches, the
length is around 60 seconds; 40
seconds for an 11-inch; and 30
seconds for a 14-inch scope.
4. Two controls affect the
brightness of Jupiter. These are
“Gain” and “Exposure Time.” A
higher gain brightens Jupiter
but will produce a grainy image.
Faster exposure times would
allow faster frame rates, but
they will dim the object.
Use the image’s histogram
as a guide for these two set-
tings. When imaging Jupiter,
the histogram should peak at
around 80 to 90 percent.
One other thing to remem-
ber is that the frame rate func-
tions as the inverse of the
exposure time. I recommend
exposure times for Jupiter
between 1/50- and 1/80-second, To derotate an image
then setting the gain to achieve of the giant planet,
first open the “Image
the recommended histogram. Measurement” window in
Load Image Measurement files
But this is not a hard rule. WinJupos.
Reduce LD value to reduce edge artifacts
Exposure times will depend on
your seeing. The second step is to
5. When imaging using the Start derotation open the “De-rotation
narrowband methane or ultra- of images” window.
violet filters, bin your images at
2x2. This technique allows the
camera to use four pixels (in a
2x2 matrix) as though they
were a single pixel. Exposure
times for these filters vary
from 0.25 second to 2 seconds.
50 or 100 depending on the size Wavelet sharpening Larger images require higher
Stacking of the image. Registax was early stacking slider values. Don’t push too
Stacking software sorts video 3. In the “Stack Options” software that started the ama- much or you will introduce
frames by quality. You then section, use percentage for the teur planetary imaging revolu- more grain in the image.
choose how many frames to amount of image you want to tion. Its most powerful tool is 2. Increasing the value of
stack for your final image. I stack. When the seeing is good the wavelet-sharpening func- the “Initial Layer” and the
recommend AutoStakkert!2 use 70 to 80 percent. For bad tion, which I highly recom- “Step Increment” will help
(AS!2). One nice feature is its seeing, use 50 to 60 percent. mend. Here are some tips for sharpen your image. Test dif-
ability to do batch processing I normally use 1.5x drizzle using wavelet: ferent settings to see which
by opening multiple files for for most of my images to 1. The “Layer” sliders con- works best with your setup.
stacking. Beginners find AS!2 increase their size. Test different trol sharpening. Slider 1 is for Then save them when you find
easy to use. Here are the steps: drizzle settings, and find out fine sharpening, and it gets the sweet spot.
1. Open the file. which works best for your con- coarser as the slider number
2. Press the “Place AP on ditions and setup. AS!2 will save increases. I normally use only Color combine
Grid” button. I recommend the resulting stacked images in sliders 1, 2, and 3 and leave Color camera users can skip
alignment point (AP) sizes of a folder automatically. sliders 4 through 6 set at 1.0. this step. Image processing
W W W.ASTR ONOMY.CO M 5
MEET THE AUTHOR
Imaging wizard
Christopher Go has sent an astounding 977
sets of images of Jupiter to Astronomy maga-
zine, starting in early 2007, and he carefully
COURTESY CELESTRON
processes each shot before sending it. This
amount of work alone places him in the top
tier of planetary imagers. Recently, he began
teaching others how to image Jupiter. Christopher Go
capture three sets (R, G, and B) result will carry the midtime of
of sequences. Do not do con- the component images.
secutive captures with the same
filter, or the resulting image Final processing
will have red and blue edges. Using image-processing soft-
You have to do an RGB set. ware, apply slight unsharp
When seeing is good, three masking to improve the image.
or four image sets are suffi- Some useful tools in Photoshop
software like Photoshop and cient, but when atmospheric are the “Despeckle” and the
On June 3, 2010, Gimp can be used to align conditions are bad, capture “Dust and Scratches” filters,
the author imaged colors. Note: Apply wavelets more image sets. De-rotation is which remove noise and
an impact scar (arrow) before you color combine. a two-stage process. grain. You’ll find them in the
in Jupiter’s atmosphere
discovered by Australian
Here’s how to combine colors STAGE 1: “Filters,” then “Noise” menus.
amateur astronomer in Photoshop: 1. Under “Recording,”
Anthony Wesley. 1. Open the wavelet-pro- open the “Image Measurement” Impact detection
cessed files. window. Since June 2010, amateur imag-
2. Convert the images into 2. Load the image. Enter the ers have detected four impact
gray scale (“Image,” then median observation time. For events. In response, program-
“Mode,” then “Grayscale”) color images, this is the time on mers developed Jupiter Impact
WHEN SEEING 3. Next, at the “Channels” the file name plus half of your Detection (JID) software to
IS GOOD, THREE windows, use the “Merge exposure time. For mono- search for them automatically.
Channels” function, and use chrome images, this should be So be sure to run all of
OR FOUR the “RGB Color” option. Make the green start time plus half your captured video streams
IMAGE SETS sure each file corresponds to the time you exposed on one through JID. Who knows? You
ARE SUFFICIENT, the correct color channel. channel. Make sure you enter might get lucky and achieve
BUT WHEN 4. Use the “Move” tool to do the time accurately. your 15 minutes of fame.
alignment adjustment. I suggest 3. Press F11 to automatically
CONDITIONS you align the Red and Blue align the wire frame to the Support research
ARE BAD, channels to the Green channel. image. If there seems to be Finally, you can help the cause
CAPTURE MORE Save your color image using the some offset on the auto-align, of science by uploading your
Green filter time. use the arrow keys to adjust the images to the Jupiter section
IMAGE SETS. X and Y positions, the “N” and of the Association of Lunar
Derotation “P” keys to adjust rotation, and and Planetary Observers, the
The fast rotation of Jupiter limits “Page Up” and “Page Down” to International Outer Planets
the exposure time. Fortunately, adjust the size of the wire Watch website, and the JPL
WinJupos software has added frame. Save the image measure- Juno support website. This will
a feature called “De-rotation,” ment. Repeat these procedures allow professionals to use your
which allows exposure times for the image set. images to give us all a better
beyond what was possible with STAGE 2: understanding of Jupiter.
a single image. Now, you can 1. Open the “De-rotation of When submitting images,
capture and derotate multiple Images” window under “Tools.” include the date and time of
image sets into an image, which 2. Load the Image Meas- capture, name of imager and
will produce less noise than a urement (*.ims) files that you location, and the three central
single image. made in Stage 1. meridian system timings of
For color, you capture mul- 3. Choose the output file Jupiter. You’ll find them in
tiple consecutive images. But type and orientation preference. WinJupos under “Tools,” then
for monochrome, you must 4. Compile the image. Your “Ephemerides.”
6 A ST R O N O M Y I N S I GH TS • MAY 2019
SKYTHIS
MONTH
Visible to the naked eye
MARTIN RATCLIFFE and ALISTER LING describe the Visible with binoculars
solar system’s changing landscape as it appears in Earth’s sky. Visible with a telescope
June 2019: Jupiter dazzles all night
more prominent. This is earth- merely a line-of-sight effect.
shine — sunlight that bounces Mars currently lies on the far
off Earth, hits the Moon, and side of the Sun from Earth
reflects back to our eyes. The while Mercury is on the near
following evening, a slightly side. The view through a tele-
fatter crescent Moon appears scope confirms this: Even
6° to Mars’ upper left. though Mars is physically
Over the next two weeks, 40 percent larger than
Mercury climbs higher and Mercury, it appears only 3.7"
Mars drops lower. The solar across — half as big as the
system’s smallest planets are inner planet’s 7.4" diameter. A
destined for a dramatic meet- telescope also shows the con-
ing just after midmonth. On trast between ruddy Mars’
June 17, the two appear side by nearly full disk and whiter
side with 28' — just less than Mercury’s half-lit phase.
the Full Moon’s diameter — Following this close con-
between them. (This is the junction, Mercury continues
separation observers in central to edge away from the Sun. It
North America will see; the reaches greatest elongation
planets appear slightly farther June 23, when it lies 25° east
apart from the eastern part of of our star and appears 11°
the continent and a bit closer high a half-hour after sunset.
Small telescopes reveal details in Jupiter’s cloud bands when the gas giant from farther west.) It then starts to sink closer
looms large, as it does throughout June. In this Hubble Space Telescope On the evening of the 18th, to the horizon, ending the
image, the Great Red Spot looks like a bloodshot eye with the shadow of
Ganymede representing its pupil. NASA/ESA/A. SIMON (GSFC) the two stand just 18' apart month 3.8° to Mars’ left.
— the closest they have been to As Mercury and Mars set
A
each other in the evening sky in the northwest, Jupiter
lthough June nights may in the west-northwest a half- in 13 years. Mercury now lies rises in the southeast. The
be short, you can pack hour after sunset. It stands above Mars and shines at mag- solar system’s largest planet
a lot of planet view- out quite nicely in the twilight nitude 0.1, some five times comes to opposition June 10,
ing into those limited glow. Four other objects join brighter than its companion. when it lies opposite the Sun
hours. Most observ- the inner planet. Capella, at This close conjunction is in our sky and remains visible
ers will spend the bulk of magnitude 0.1 the brightest
their time with Jupiter, which star in Auriga, stands 21° to Jupiter at its finest
reaches peak visibility and is Mercury’s upper right. Mars
up all night. But you’ll also lies 16° to Mercury’s upper
want to watch Mercury and left and at the same altitude OPHIUCHUS
Mars as they have their closest as Capella. Glowing at magni- LIBR A
evening conjunction in more tude 1.8, the Red Planet may
than a decade. Be sure to turn be hard to see in twilight
your attention toward Saturn without binoculars. Finally, Jupiter
and its magnificent rings as the twin stars Castor and
Antares
midnight approaches, then Pollux in Gemini appear 13°
wrap up a memorable night directly above the slightly SAGIT TARIUS
LUPUS
with a view of Venus in morn- fainter Mars. SC ORPIUS
ing twilight. A two-day-old crescent
But your first order of Moon joins the party June 4. Saturn 10°
business these June nights Luna lies 6° to Mercury’s left,
should be to track down and both stand some 9° high June 10, 11 P.M.
Mercury and Mars. On the Looking south-southeast
30 minutes after sundown. As
1st, Mercury shines at magni- the sky darkens, watch the The giant planet peaks at opposition June 10, but it reigns supreme against
tude –1.0 and appears 6° high unlit side of the Moon grow the backdrop of Ophiuchus all month. ALL ILLUSTRATIONS: ASTRONOMY: RICK JOHNSON
8 A ST R O N O M Y I N S I GH TS • MAY 2019
RISINGMOON
A terrific trio of conspicuous craters Ptolemaeus, Alphonsus, and Arzachel
Three magnificent large craters ancient craters hidden under a
Ptolemaeus
beckon observers the evening blanket of debris.
of June 10, when the Moon is The smaller impact that cre-
less than a day past First Quarter ated Alphonsus immediately to
phase and appears slightly more the south of Ptolemaeus pro-
than half-lit. The northernmost duces more distinct features and
and largest of the three craters, a higher central peak. Return to
Ptolemaeus, lies just south of this feature every hour or so and
the lunar equator. It sports a note how quickly the spire’s Alphonsus
rugged rim that casts long shad- shadow retreats under the rising
ows onto the relatively smooth Sun. The unusual ridge that
floor. A small crater northeast of bisects Alphonsus lines up with
Ptolemaeus’ center affords a other linear features that point
good test of your telescope’s back toward Imbrium.
Arzachel
optics and seeing conditions. The youngest of the three
Like most large impact fea- craters is Arzachel to the south. N
tures, Ptolemaeus probably pos- Its rim and inner walls appear
sesses a complex central peak sharper than those of its north-
E
— but you won’t see it no mat- ern neighbors, which suffered
ter how hard you look. Lunar sci- many more millennia of impacts. The First Quarter Moon boasts three large and spectacular craters just
entists suspect that it lies buried Don’t hesitate to return south of the lunar equator. CONSOLIDATED LUNAR ATLAS/UA/LPL; INSET: NASA/GSFC/ASU
under deposits sprayed out dur- to this region on subsequent
ing the excavation of giant Mare nights. Although the higher gray spots on Alphonsus’ floor. studies show the composition
Imbrium to the northwest. You Sun masks topographic relief, These are deposits of ash of the ash is similar to that of
might also glimpse a few subtle it reveals surface composition. gently sprayed out during vol- the lava that welled up to flood
depressions, telltale signs of Notice the handful of darker canic eruptions. Spectroscopic the large lunar maria.
all night. Opposition brings
Jupiter closest to Earth, so it
METEORWATCH
shines at its brightest for the
year: magnitude –2.6. It brings
a touch of brilliance to the
Early summer’s Pearly noctilucent clouds
otherwise faint constellation twilight clouds
Ophiuchus the Serpent-bearer.
Jupiter’s proximity also Despite the lack of major meteor
showers in June, sporadic meteors
makes it appear larger than
continue to light up the sky. These
at any other time in 2019. Its
random flashes arise when tiny
46"-diameter disk should dis-
grains of dust slam into Earth’s
play a wealth of detail through
atmosphere and friction with air
telescopes of all sizes. A paral- molecules incinerates them. Under
lel pair of relatively dark belts, a dark sky, observers typically see
one on either side of a brighter a half-dozen or so of these random
zone that coincides with the meteors per hour.
planet’s equator, dominates Similarly fine meteoritic dust June’s extended twilight offers ideal conditions for northern skygazers
the view. In moments of plays a role in producing summer’s to see these highly reflective, high-altitude clouds. NASA
steady seeing, look for a whole gorgeous noctilucent clouds.
series of alternating belts and These silver-blue clouds form condense on dust particles. Search for them in twilight an
zones as well as the dusky about 50 miles up (10 times higher They typically appear in early hour or two after sunset, when
north and south polar regions. than cirrus), where Earth’s atmo- summer from latitudes our star still illuminates these
You also might notice several sphere is coldest, when ice crystals between 50° and 60° north. high-altitude clouds.
dark and white spots lurking
near the boundaries between
the belts and zones. The Great OBSERVING Jupiter reaches its 2019 peak June 10, when the gas giant planet
HIGHLIGHT shines at magnitude –2.6 and spans 46" through a telescope.
W W W.ASTR ONOMY.CO M 9
Hunt down Jupiter’s four bright satellites
WHEN TO VIEW THE PLANETS Jupiter
S
Callisto
EVENING SKY MIDNIGHT MORNING SKY
Io Ganymede
Mercury (northwest) Jupiter (south) Venus (northeast) W Europa
Mars (northwest) Saturn (southeast) Jupiter (southwest)
Jupiter (southeast) Saturn (southwest)
June 11, 4:00 A.M. EDT 1'
Uranus (east)
Neptune (southeast) The giant world’s moons show up nicely through small scopes, but they can
be tricky to identify. Their arrangement at opposition makes the task easy.
Red Spot appears about half the planet’s face or lies near minutes, you should notice its Saturn lies in northern
the time — whenever the plan- the limb. shadow immediately to the Sagittarius, just south of that
et’s 10-hour rotation carries it The night of opposition moon’s east, with the two over- constellation’s Teaspoon
onto Jupiter’s Earth-facing offers a good opportunity to lapping. Ganymede lies north asterism. It shines at magni-
hemisphere. acquaint yourself with these of Io and begins to transit at tude 0.2 in mid-June and
The sharpest views of the so-called Galilean moons. If 11:28 p.m. Its shadow falls on appears four times brighter
giant world come when it lies you look during the morning the cloud tops just southeast of than any of the Archer’s stars.
highest in the south. Jupiter hours of June 11, you’ll see Io, the moon. Because Ganymede The best time to view
peaks at an altitude of about Europa, and Ganymede lined lies farther from Jupiter than Saturn through a telescope
30° at 1 a.m. local daylight up to Jupiter’s east while Io, its shadow appears slightly occurs during the early morn-
time the night of opposition. It Callisto stands alone to the more separated from the ing hours when it climbs
reaches the same benchmark planet’s west. moon. Io completes its transit highest in the south. Even the
about a half-hour earlier with The month’s most dra- at 12:33 a.m., when Ganymede smallest telescope delivers
each passing week. Still, the matic scene occurs the follow- is about halfway across the stunning views. The planet’s
planet lies nearly as high and ing night, however. Both Io giant planet’s disk. The outer disk measures 18" across
the views are almost as good and Ganymede start to cross moon completes its trek while the rings span 41" and
for a couple of hours on either Jupiter’s disk the evening of around 1:40 a.m. tilt 24° to our line of sight.
side of these times. June 11. But with the gas giant Saturn lies 30° east of Saturn’s disk shows little
Jupiter’s four brightest so close to opposition, the Jupiter, which means it trails detail, though you might spot
moons create a scene that shadow that each satellite about two hours behind its an equatorial belt and a dark
changes dramatically from casts falls onto the jovian bigger brother. The ringed polar hood.
night to night. Their motions cloud tops almost directly planet rises around 11 p.m. Although Saturn’s moons
sometimes appear noticeable beneath the moon. local daylight time June 1 and don’t glow as brightly as
even within minutes, particu- Io’s transit begins at some two hours earlier by Jupiter’s Galilean satellites,
larly when a satellite transits 10:22 p.m. EDT. Within five month’s end. small scopes reveal at least
COMETSEARCH
A killer takes aim at the Whale Comet ASASSN (C/2018 N2)
Comet observers often hope a hour before morning twilight N
ξ2
new discovery will herald a commences. Look for the faint 30
bright target to feed their pas- smudge of light as it glides
sion. This does happen, though northward between magnitude
27
not often. Two arrivals bright- 4.9 Nu (ν) Ceti and magnitude Path of Comet ASASSN
ened to 9th magnitude in late 4.3 Xi2 (ξ2) Cet. Astronomers dis-
CETUS
2018, but unless we get a similar covered this comet in July 2018, 24
surprise this month, we’ll have to and it appears destined to peak E
be satisfied with a comet that at 11th magnitude this autumn. 21
reaches only 12th magnitude. A harder target lies on the
To catch Comet ASASSN border of Centaurus and Lupus
(C/2018 N2), wait for the Moon- in early June. Comet ATLAS ν 18
free period at the end of June. (C/2017 M4) passes between
ASASSN — short for the All- magnitude 2.7 Beta (β) Lupi and June 15
Sky Automated Survey for magnitude 3.1 Kappa (κ) Centauri 0.5°
Supernovae program — then during June’s first week. You’ll
resides in northeastern Cetus need a 12-inch or larger scope to Reserve some time on June mornings to track down this faint comet as it
the Whale and rises about an spot this 13th-magnitude object. slides to the northeast against the background stars of Cetus.
10 A ST R O N O M Y I N S I GH TS • MAY 2019Mercury tangos with Mars
Castor
LOCATINGASTEROIDS
Pollux
Tangled up in Berenice’s tresses
Asteroid 2 Pallas glows at 9th and star-hop to Pallas’ position
Mars Mercury
magnitude in June, making it a with the help of the chart below.
nice target for asteroid seekers. If you want to see the aster-
GEMINI Visible with some effort through oid move in a single evening,
binoculars, it’s a cinch to find June 12 and 26 offer the best
5° with the extra light-gathering chances. Both nights, Pallas
power of a small telescope. skims near a similarly bright star
Pallas lies high in the south that helps you gauge its motion.
June 17, 45 minutes after sunset after darkness falls. To find it, When Heinrich Olbers dis-
Looking west-northwest
first locate Arcturus, the magni- covered Pallas in 1802, astrono-
tude –0.04 orange giant in mers thought it might be the
These two planets slide within 0.3° of each other June 18. They have not
passed this close in the evening sky since 2006. Boötes that ranks as the night second “missing planet” in what
sky’s fourth-brightest star. Next, seemed like an abnormally large
move 6.4° west-northwest to gap between Mars and Jupiter.
four of them. Titan is the easi- the time twilight starts to
5th-magnitude 6 Boötis, then Scientists later figured out that
est. It shines at 8th magnitude paint the sky. The planet
another 2.4° northwest to 6th- the gravity of massive Jupiter
and shows up through any shines at magnitude 5.8
magnitude 2 Boo. From there, prevented any major planet
instrument. This large moon and shows up quite easily
cross the border into eastern from forming at that distance
orbits Saturn in 16 days, pass- through binoculars. Coma Berenices, Berenice’s Hair, from the Sun.
ing south of the ringed world The hardest part of finding
the mornings of June 5 and 21 Uranus is zeroing in on the
Pallas continues its nice run
and north of the planet on the right star field. The world lies
13th and 29th. Look for three in southern Aries, about 10° N
10th-magnitude moons — south of the Ram’s brightest
Tethys, Dione, and Rhea — star, magnitude 2.0 Hamal
closer to Saturn. (Alpha [α] Arietis). This is a
Scan 60° east-northeast of sparse area of sky, however.
Saturn and you’ll arrive at First locate 6th-magnitude June 1
B O ÖTE S Path of Pallas 6
Neptune. The solar system’s 19 Ari, which lies 8° south of 11
most distant major planet rises Hamal and shows up to the
E 16
shortly after 1 a.m. local day- naked eye from under a dark
2
light time June 15 and climbs sky. Center 19 Ari in your 21
25° above the southeastern binoculars and you’ll see 26
horizon by the time twilight Uranus 2.4° to its south. C OM A BE RENICES
begins. Neptune glows at mag- To confirm your planet sight-
nitude 7.9, so you’ll need bin- ing, swing a telescope in its 6 July 1
oculars or a telescope to see it. direction. Uranus shows a
The outer world resides in 3.5"-diameter disk with a dis- 1°
northeastern Aquarius, in the tinctive blue-green color.
same binocular field as magni- This 9th-magnitude object rides high in the south on June evenings as
Morning twilight is well
it traverses the sparse star fields of eastern Coma Berenices.
tude 4.2 Phi (ϕ) Aquarii. It underway before our final
begins June 1.2° east-northeast planet appears. Venus rises
of this star and crawls 0.1° far- an hour before the Sun on
ther away by the latter half of June 1 in the company of a stands just 3° high a half-hour when the Sun lies farthest
the month. This places the slender crescent Moon. The before sunup June 30, when north in our sky, and is the
planet within 0.4° — slightly two stand about 6° apart and you’ll need a haze-free sky and reason why the days are so
less than the Full Moon’s a similar distance above the an unobstructed horizon to see long and the nights so short in
diameter — south of the mag- eastern horizon a half-hour it against the twilight glow. the Northern Hemisphere.
nitude 5.6 star 96 Aqr. When before sunrise. Although The inner planet is heading
viewed through a telescope, Venus shines brilliantly at toward its mid-August supe- Martin Ratcliffe provides plane-
Neptune displays a blue-gray magnitude –3.8, the Sun’s rior conjunction, and will dis- tarium development for Sky-Skan,
disk that appears 2.3" across. glare drowns it out within appear from view in early July. Inc., from his home in Wichita,
Uranus slowly emerges into the next 15 minutes. Earth reaches its summer Kansas. Alister Ling, who lives in
a dark sky by the end of June. Venus slowly sinks lower solstice at 11:54 a.m. EDT on Edmonton, Alberta, has watched
On the 30th, it rises around as the month progresses. It June 21. This marks the instant the skies since 1975.
2 a.m. local daylight time and
climbs 15° high in the east by GET DAILY UPDATES ON YOUR NIGHT SKY AT www.Astronomy.com/skythisweek.
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