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A smudge near Jupiter

A smudge near Jupiter


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I was looking at the Jupiter for the first time today and I have noticed a smudge near it. Could someone explain what it is, please? I was looking online but did not find anything. So I thought that some kind of defect in my setup but I couldn't get rid of it. I mean the thing below its moons.

Edit1: My telescope is a Celestron AstroMaster 76 ESQ. The smudge was there no matter what eyepiece I have used. I was able to see it even without a camera.

Edit2: I was watching it for about 10 minutes, and the smudge was moving along with the rest of the objects.

I took just this one image for the StackExchange purposes. I have put the camera in front of an eyepiece to take the picture.

Thank you


The faint green smudge looks to me like a flare (that is, an optical defect called a flare).

However I'd expect a flare to be symmetric with the bright object it relates to about the center of the field of view. This does imply either the image is off center (e.g. the camera is off center or the image is a crop off center) or there's a misalignment of your optics.

This question on Physics SE is about correcting flare in a telescope and may be relevant.

The similar question Does this smartphone photo show Mars just below the Sun? and its answers contain some other examples.


The OP's comment under another answer says:

I would expect the flare to move depending on how I move with my telescope. What I saw, however, was an object that was always moving with the planet at the same relative place to it.

So it may in fact not be lens flare, but instead some kind of misalignment between two parallel surfaces. Like an optical wedge type of thing. A wedge prism for example, with proper antireflection coatings will not tend to show a double image, but here the image is very intense and the smudge is very weak, so it could be a double reflection between two almost-parallel surfaces.

A test would have been to see if the gap between Jupiter and the smudge scaled with magnification by changing eyepieces; if Jupiter is twice as big is the gap twice as big also?

I see a lot of chromatic aberration, and this is a 3 inch refractor. I wonder if someone took the objective lens apart, separating the achromat pair (assuming it's an air gap, which some are) and then put them back together incorrectly? It's possible that could result in a small wedge error, depending on how the lens was keyed and spacers implemented.

No, the Astromaster 76EQ is a 76 mm f/9.21 Newtonian Reflector! One of the eyepieces has a built-in image corrector(?!) and the other doesn't?

The secondary mirror has a 46% obstruction by diameter (21% by area) which sounds absolutely huge for an f/9.21 Newtonian, so something may be going on inside.

click for full size view


ALMA Detects Strong Winds in Stratosphere of Jupiter

This image shows an artist’s impression of winds in Jupiter’s stratosphere near the planet’s south pole, with the blue lines representing wind speeds these lines are superimposed on a real image of Jupiter, taken by the JunoCam imager aboard NASA’s Juno spacecraft. Image credit: ESO / L. Calçada / NASA / JPL-Caltech / SwRI / MSSS.

Astronomers were aware of strong winds near Jupiter’s poles, but much higher up in the atmosphere, hundreds of kilometers above the focus area of the new study.

Previous studies predicted that these upper-atmosphere winds would decrease in velocity and disappear well before reaching as deep as the stratosphere.

“The new ALMA data tell us the contrary. Finding these strong stratospheric winds near Jupiter’s poles was a real surprise,” said Dr. Thibault Cavalié, an astronomer in the Laboratoire d’Astrophysique de Bordeaux.

Dr. Cavalié and colleagues used ALMA to analyze hydrogen cyanide molecules that have been moving around in Jupiter’s stratosphere since the impact of comet Shoemaker-Levy 9, which collided with the gas giant in 1994.

The ALMA data allowed the team to measure the Doppler shift — tiny changes in the frequency of the radiation emitted by the molecules — caused by the winds in this region of the planet.

“By measuring this shift, we were able to deduce the speed of the winds much like one could deduce the speed of a passing train by the change in the frequency of the train whistle,” said Dr. Vincent Hue, a planetary scientist at the Southwest Research Institute.

“The most spectacular result is the presence of strong jets, with speeds of up to 1,450 kmh, which are located under the aurorae near the poles,” Dr. Cavalié said.

These wind speeds are more than twice the maximum storm speeds reached in Jupiter’s Great Red Spot and over three times the wind speed measured on Earth’s strongest tornadoes.

“Our detection indicates that these jets could behave like a giant vortex with a diameter of up to four times that of Earth, and some 900 km (559 miles) in height,” said Dr. Bilal Benmahi, an astronomer in the Laboratoire d’Astrophysique de Bordeaux.

In addition to the surprising polar winds, the astronomers used ALMA to confirm the existence of strong stratospheric winds around the planet’s equator, by directly measuring their speed, also for the first time.

The jets spotted in this part of the planet have average speeds of about 600 kmh (373 mph).

“These ALMA results open a new window for the study of Jupiter’s auroral regions, which was really unexpected just a few months back,” Dr. Cavalié said.

The findings were published in the journal Astronomy & Astrophysics.

T. Cavalié et al. 2021. First direct measurement of auroral and equatorial jets in the stratosphere of Jupiter. A&A 647, L8 doi: 10.1051/0004-6361/202140330


NASA's Juno probe beams back razor-sharp images of Jupiter's moon Ganymede

Orbiting Jupiter , NASA's Juno spacecraft streaked past Ganymede on Monday, beaming back the first close-up views of the largest moon in the solar system since the Galileo orbiter last flew past in 2000.

"This is the closest any spacecraft has come to this mammoth moon in a generation," Scott Bolton, the Juno principal investigator at the Southwest Research Institute, said in a statement. "We are going to take our time before we draw any scientific conclusions, but until then we can simply marvel at this celestial wonder, the only moon in our solar system bigger than the planet Mercury."

NASA's Juno spacecraft captured high-resolution views of Jupiter's moon Ganymede during a flyby Monday at an altitude of about 645 miles. The flyby was the first close-up look at the big moon since NASA's Galileo orbiter flew past for the last time in 2000. NASA/JPL-Caltech/SwRI/MSSS

Juno raced by Ganymede at 1:35 p.m. EDT Monday, passing within about 645 miles of the moon and capturing a razor-sharp view of the cratered world, thought to harbor a sub-surface sea beneath an icy crust. Along with capturing fresh images, Juno's suite of science instruments also collected data.

"Ganymede's ice shell has some light and dark regions, suggesting that some areas may be pure ice while other areas contain dirty ice," Bolton said before the flyby. Juno "will provide the first in-depth investigation of how the composition and structure of the ice varies with depth, leading to a better understanding of how the ice shell forms and the ongoing processes that resurface the ice over time."

Juno was launched from Cape Canaveral in 2011 and braked into orbit around Jupiter on July 4, 2016. Still going strong at the end of its initial two-year primary mission, NASA has now approved two extensions, the latest running from this summer to mid-2025.

Built to study Jupiter's deep interior, its atmosphere, magnetic field and aurorae, Juno has made repeated close passes over the planet's north polar regions, providing startling views of never-before-seen polar storms, detecting signs of a somewhat diffuse core and collecting gigabytes of data to better understand the planet's overall behavior.

Space & Astronomy

The probe's 53-day polar orbit was set up to slowly move the point of closest approach northward as the flight progresses. On the far side of the orbit, the spacecraft initially crossed the equatorial plane well beyond the orbit of Ganymede.

But the point of closest approach has moved inward throughout the mission and the latest extension provided a golden opportunity to make close flybys of Ganymede, Europa and volcanic Io.

A slightly higher-resolution view of Ganymede's far side, illuminated by sunlight scattered from Jupiter's atmosphere, shows the surface "wrinkles" in more detail. NASA/JPL-Caltech/SwRI

"We're going to cross the orbital plane near Ganymede and as the orbit keeps progressing farther and farther north, the (equatorial) crossing moves farther and farther in," Bolton said in an earlier interview. "So first, we cross near Ganymede and then we keep moving in and we cross near Europa. Eventually we cross near Io, and then we're even inside of Io."

The Ganymede encounter Monday was set up to use the moon's gravity to bend the trajectory slightly, reducing Juno's orbital period by about 10 days. That, in turn, sets up a flyby of icy Europa on September 29, 2022, and two close flybys of Io on December 30, 2023, and February 3, 2024.

"So we have these close flybys of the satellites that are going to allow us to now point our instruments at the satellites, get the first close-up analysis and look for changes since the days of Galileo and Voyager," Bolton said.

Juno is not equipped with a telescope for close-up, narrow-angle observations. Instead, its "Junocam" imager was intended primarily for wide-angle, contextual observations and public outreach, providing spectacular hemispheric views of Jupiter's turbulent atmosphere.

Bolton expects equally stunning views from the Ganymede, Europa and Io flybys.

"When we're really far away, we can't make a high-resolution shot," he said. "But when we're close up, we get a wide field of view at high resolution." That wide field of view, he said, "makes all the difference when you're looking at it, saying do I understand the context?"

Junocam captured almost an entire side of Ganymede during the probe's flyby Monday. Shots using different filters will be combined later to provide color views, resolving surface features as small as six-tenths of a mile across.

Juno's navigation camera captured a more zoomed-in view of Ganymede's dark side, illuminated by sunlight reflected from Jupiter. Additional images stored on board the spacecraft will be beamed back later.


Jupiter and Saturn

Hey guys first post! Thanks for all the great posts. I pretty much did all my research via this forum. So I got a zhumell z130 and finally had clear skies last night. What an upgrade from my 10x50 binoculars! Using "Turn left at Orion" I found M13 after several hours of trying and was blown away by that little smudge. It was so satisfying to finally find it.

Saturn I only caught a glimpse of the rings. Most of the time the rings and saturn just looked pale yellow or white oblong smudge. Could it be do to seeing conditions? Or that it was low on the horizon for me so more atmosphere? I was using both the 10mm and 25mm eye pieces.

Jupiter - the moons were amazing but like Saturn the planet was mostly just yellow/white. I didn't see any surface details.

Considering I found M13 and was looking at lots of stars I don't think its the telescope collimination. Additionally I made collimination cap and everything looked fine and the star test looked ok.

My skies are bortle 8 if that makes a difference

Edited by JustAnotherScott, 08 May 2020 - 07:45 AM.

#2 Starman27

Welcome to CN. The seeing conditions you described are certainly not the best for planetary viewing. Low to the horizon provides very poor seeing. Enjoy M13.

#3 Waddensky

Hi and welcome! Not sure where you live, but from mid-northern latitudes both Jupiter and Saturn will remain low above the horizon this year (and the next years, for that matter). You are correct in assuming that this will make a detailed observation difficult. It's just too much air to pierce through.

Mars will be much better later this year! Or give Venus a go in the evening. No surface details there, but a lovely crescent shape at high magnifications.

Light pollution doesn't affect planetary observing that much. And don't forget that by gaining experience, you will be able to see more detail with the same scope over time. It's a matter of developing a sharp eye for tiny details.

#4 SeaBee1

Hey guys first post! Thanks for all the great posts. I pretty much did all my research via this forum. So I got a zhumell z130 and finally had clear skies last night. What an upgrade from my 10x50 binoculars! Using "Turn left at Orion" I found M13 after several hours of trying and was blown away by that little smudge. It was so satisfying to finally find it.

My questions:

Saturn I only caught a glimpse of the rings. Most of the time the rings and saturn just looked pale yellow or white oblong smudge. Could it be do to seeing conditions? Or that it was low on the horizon for me so more atmosphere? I was using both the 10mm and 25mm eye pieces.

Jupiter - the moons were amazing but like Saturn the planet was mostly just yellow/white. I didn't see any surface details.

Considering I found M13 and was looking at lots of stars I don't think its the telescope collimination. Additionally I made collimination cap and everything looked fine and the star test looked ok.

Thoughts?

Added:

My skies are bortle 8 if that makes a difference

Saturn and Jupiter are a bit too close to the horizon at the moment for optimal viewing. Later this year, when they become late evening objects, they will be higher, near the meridian, and better to view. To get the best views of either, you will need to achieve closer to 100X with your 'scope/eyepiece combo. Something like a 5mm to 8mm eyepiece should get you there.

Be patient. the planetary show only gets better from this point forward.

#5 JohnBear

Late this summer when the planets are near opposition, and high(er) in the sky, the viewing will be much better - Not "hubble better", but you will see a lot more. Glad to see you are using the Z130 as a starter scope. It should serve you really well in the beginning, and then it will become your favorite Grab & Go scope for a long, long time - same goes for the AWB OneSky (pay attention noobs looking for their "first telescope").

As the pandemic fades away you can find some local astronomy friends, pick a nearby "darker site", and share new of equipment and eyepieces, as well as knowledge and experience - a great cost effective way to learn and grow quickly and minimize newbie frustration. That will also help you select your best upgrade eyepieces for the Z scope without wasting time or money on trial and error purchasing expensive new oculars and other equipment.

#6 CeeKay

Hey guys first post! Thanks for all the great posts. I pretty much did all my research via this forum. So I got a zhumell z130 and finally had clear skies last night. What an upgrade from my 10x50 binoculars! Using "Turn left at Orion" I found M13 after several hours of trying and was blown away by that little smudge. It was so satisfying to finally find it.

My questions:

Saturn I only caught a glimpse of the rings. Most of the time the rings and saturn just looked pale yellow or white oblong smudge. Could it be do to seeing conditions? Or that it was low on the horizon for me so more atmosphere? I was using both the 10mm and 25mm eye pieces.

Jupiter - the moons were amazing but like Saturn the planet was mostly just yellow/white. I didn't see any surface details.

Considering I found M13 and was looking at lots of stars I don't think its the telescope collimination. Additionally I made collimination cap and everything looked fine and the star test looked ok.

Thoughts?

Added:

My skies are bortle 8 if that makes a difference

Had some good views of both over the last couple of mornings, but this morning it was B.A.D. - same conditions as you described. Like the others have stated, the viewing will get better as we head into Summer.

#7 JustAnotherScott

Hi and welcome! Not sure where you live, but from mid-northern latitudes both Jupiter and Saturn will remain low above the horizon this year (and the next years, for that matter). You are correct in assuming that this will make a detailed observation difficult. It's just too much air to pierce through.

Mars will be much better later this year! Or give Venus a go in the evening. No surface details there, but a lovely crescent shape at high magnifications.

Light pollution doesn't affect planetary observing that much. And don't forget that by gaining experience, you will be able to see more detail with the same scope over time. It's a matter of developing a sharp eye for tiny details.

I did get some glimpses of Venus! It was really cool and such a big step up from my binoculars.

#8 rhetfield

If you are too far north, they will be low to the horizon. They are best seen right now at sunrise. I am near Chicago and they are at a decent enough height at that time. Even with the 25mm in the collapsible truss version of your scope, I can just discern the rings on saturn (as ears on the disk) and on a good morning can just see the 2 main bands on Jupiter. Being in Bortle 8 does not matter with planets. With the 5mm, I can see the red spot on jupiter (hard to see in the lower band) and the cassini division on Saturns rings (also hard). Saturn cloud bands are subtle at best and often you will not see them. Note that the planets are still not at their closest approach.

I would take another look at star collimation. Be aware that checking it and adjusting it should be done at the highest magnification possible. For me, that is with a 5mm in a barlow - the absolute upper limit of your scope - more than is useful for the planets.

I would consider picking up a decent 2x barlow. If it is one that can convert to 1.5x, that would be great. Then pick up an eyepiece that is around 7mm. That way, you have 7mm, 5mm, and 3.5mm. Star collimate at 3.5mm and the planets will look awesome at 5mm and hopefully better at 3.5mm. Big improvement over looking at them with the 10mm.

Also, your scope may need 30-45 minutes to adjust to temperatures outside - depending on how cold it is - before it performs at its best.

Edited by rhetfield, 08 May 2020 - 10:35 AM.

#9 JustAnotherScott

.

I would consider picking up a decent 2x barlow. If it is one that can convert to 1.5x, that would be great. Then pick up an eyepiece that is around 7mm. That way, you have 7mm, 5mm, and 3.5mm. Star collimate at 3.5mm and the planets will look awesome at 5mm and hopefully better at 3.5mm. Big improvement over looking at them with the 10mm.

Also, your scope may need 30-45 minutes to adjust to temperatures outside - depending on how cold it is - before it performs at its best.

Thanks for the advice! I have an Orion Shorty on the way already which can be switched to a 1.5 like you say.

I was looking at 6.5mm to 5mm eyepieces. Whats it like when you get to 260 magnification?

#10 chrysalis

As others mentioned, seeing conditions and proximity to the horizon play havoc with ability to usefully employ magnification on the planets, although I would have thought you might have had better views.

Go to the below website to get a good representation of what seeing conditions will be like near you by choosing an "observatory" near your location. (FYI, you can see mine in NC under "Chrysalis Observatory" . ) I **think** Atila still adds observatories if you are interested.

#11 rhetfield

Thanks for the advice! I have an Orion Shorty on the way already which can be switched to a 1.5 like you say.

I was looking at 6.5mm to 5mm eyepieces. Whats it like when you get to 260 magnification?

Edited by rhetfield, 08 May 2020 - 12:42 PM.

#12 SeattleScott

Thanks for the advice! I have an Orion Shorty on the way already which can be switched to a 1.5 like you say.

I was looking at 6.5mm to 5mm eyepieces. Whats it like when you get to 260 magnification?

260x is probably aggressive. 50x per aperture is one thing for a refractor. A little different story for a mirrored scope, especially an entry level one. The cheap focuser also might make precise collimation and focus at such high power difficult. I would think 200x is probably a more realistic maximum magnification.

A Meade 6.5 HD-60/Celestron Xcel LX would be a good medium power eyepiece that you could barlow to get to 200x. Very sharp, well corrected for F5. Comfortable eye relief and wider viewing angle than your bargain basement Kellners. It will show you the difference between a $75 eyepiece and a $15 eyepiece. The danger is you might also “need” to get the 25mm and 9mm to replace your 25 and 10 Kellners.

Edited by SeattleScott, 08 May 2020 - 01:19 PM.

#13 JustAnotherScott

260x is probably aggressive. 50x per aperture is one thing for a refractor. A little different story for a mirrored scope, especially an entry level one. The cheap focuser also might make precise collimation and focus at such high power difficult. I would think 200x is probably a more realistic maximum magnification.

A Meade 6.5 HD-60/Celestron Xcel LX would be a good medium power eyepiece that you could barlow to get to 200x. Very sharp, well corrected for F5. Comfortable eye relief and wider viewing angle than your bargain basement Kellners. It will show you the difference between a $75 eyepiece and a $15 eyepiece. The danger is you might also “need” to get the 25mm and 9mm to replace your 25 and 10 Kellners.

I always listen to advice from another Scott. Thanks!

#14 rhetfield

260x is probably aggressive. 50x per aperture is one thing for a refractor. A little different story for a mirrored scope, especially an entry level one. The cheap focuser also might make precise collimation and focus at such high power difficult. I would think 200x is probably a more realistic maximum magnification.

A Meade 6.5 HD-60/Celestron Xcel LX would be a good medium power eyepiece that you could barlow to get to 200x. Very sharp, well corrected for F5. Comfortable eye relief and wider viewing angle than your bargain basement Kellners. It will show you the difference between a $75 eyepiece and a $15 eyepiece. The danger is you might also “need” to get the 25mm and 9mm to replace your 25 and 10 Kellners.

#15 Tony Flanders

I was looking at 6.5mm to 5mm eyepieces. Whats it like when you get to 260 magnification?

The highest I have ever used my Z130 happily is 162X with a 4-mm eyepiece. Even at that magnification, it's pretty hard to achieve critical focus with this telescope's rather crude focuser. The scope's optics are good but not great, and the difference begins to show at those magnifications. In addition, atmospheric stability usually starts to become a problem around there.

All in all, I'm usually happier when I back off to 130X, which is a very satisfying magnification with this telescope.

#16 Vince_Maine

I am only a month or so into my visual journey, so take this all lightly, but your experience with Jupiter and Saturn sounds like seeing conditions. Not to mention what many have already: they are quite low in the sky still. A little time Googling can help you anticipate when their positions will be more favorable in the coming months/years/decades. As a newbie, I am still shocked at how much of a difference the atmosphere makes. Like you, I'll be able to enjoy clusters and other niceties, but when I push it to/past 100X on Saturn or Jupiter in the early morning is when the true test results show.

Have you found a good Clear Sky Chart for your area? It has been helping me establish a viewing session's plans and expectations. i.e for Southern Maine: https://www.cleardar. tObMEkey.html?1

Keep at it. I got lucky on my first early AM look at J/S a few weeks ago with a good patch of steady air, and loved over how sharp/detailed it was. A handful of sessions later, and I've had to hold that crisp image in my head ever since, just KNOWING that I'll see it again. Maybe once this SNOWSTORM IN MAY finishes haha.

#17 JustAnotherScott

Got a second look at Saturn and Jupiter last night. from a different location.

Everything looked much better especially as they rose. I could see several of Saturns moons and as it rose using the 10mm. The rings started showing better when it got higher. I didn't realize I could see the moons too that surprised me.

Jupiter was cool. I could make out two distinct darker bands. I'm getting my barlow tomorrow so excited to see what they look like in that.

Found the Bee Hive cluster. That was super cool. It was much more impressive than M13. Found M13 again after a lot of work. Very cool.

Will M13 look better at 130 magnification or is my mirror to small to see more details?


Comments

February 1, 2011 at 12:28 am

Surely it's time to create a global network of automated telescopes to continuously monitor Jupiter -- and other solar system objects. The technology to do so is widely available, and the results would be fascinating.

You must be logged in to post a comment.

February 4, 2011 at 6:03 pm

Thank you for posting, Josh Barnes. We might get a clearer picture of the collision frequency in the Solar system as a whole, in addition to being able to sample more kinds of objects. But would an automated system have picked this up? Somebody has to report it before the big 'scopes can be called in.

It's probably not a Trojan asteroid because we expect them to be icy. It could easily be a burnt-out comet. But most likely it had entered an integer resonance, like 1:2 or 1:3 or 2:3 or something like that.

I thought of something while typing this: could an automated system examine the space AROUND Jupiter or other gas giants? If it's not looking at swirling clouds, maybe a machine could get a trajectory of something coming in.


Your best chance to see Jupiter this year

Mighty Jupiter, the king of the planets, comes to opposition at 08:00 UT on 14 July, the moment when it lies opposite the Sun in sky at a distance of 619.4 million kilometres (384 million miles), or 4.139 astronomical units. This is the most favourable time to observe the so-called ‘superior planets’ (those apart from Mercury and Venus, which are termed ‘inferior planets’).

Jupiter’s Great Red Spot is well on show in this image taken on 5 July 2020. Image: Christopher Go.

Jupiter, by far the Solar System’s dominant planet and the one that offers the most to observers of all levels or experience, is at its 2020 best on the nights of 13/14 and 14/15 July, when it’s a brilliant magnitude –2.8 beacon rather low in the southern sky among the stars of Sagittarius as soon as what passes for darkness as this time of the year descends. The presence of Saturn, the gorgeous ringed planet which comes to opposition itself on 20 July, lying just six to seven degrees to the east of Jupiter, adds greatly to the spectacle.

As Jupiter doesn’t achieve an altitude of 20 degrees at any time from our shores, observers living in towns and cities will have to find a good observing spot with a flat horizon from the south-east around to the south-west if they don’t want to spend the night dodging buildings and peeking between trees.

Jupiter lies among the stars of Sagittarius when it’s at opposition. It culminates at around 1am at a maximum altitude of 17 degrees (from the south of England). All AN graphics by Greg Smye-Rumbsby.

Jupiter culminates (reaching its highest point on the southern meridian) at about 1am BST around opposition: from London, it culminates at around +16.5 degrees altitude at 1.04am BST (12:04 UT) from Manchester, it peaks at between 14 and 15 degrees at 1.16am BST (12:16 UT) and in Edinburgh it reaches just over 12 degrees altitude at 1.20am BST (12:20 UT).

Jupiter will richly reward observers who have gone the extra mile to locate it, offering a generous-sized disc to enjoy, large enough indeed for even a humble pair of binoculars to resolve and for a small telescope to reveal its major bright zones and dark belts in its turbulent and ever-changing clouds tops.

Jupiter’s cloud tops are generally seen as well-defined dark belts and bright zones.

See the Great Red Spot

The gas giant’s most famous individual feature is the Great Red Spot (GRS), a long-lived anticyclonic storm that has been raging in the planet’s South Tropical Zone (STrZ) for possibly 350 years. A telescope in the 150mm (six-inch) class should show the GRS at the times when it rotates into view (Astronomy Now has monthly listings of the GRS’s appearances on the Jovian disc), along with a host of other transient features, such as white and dark ovals and festoons, but have a go with a smaller-aperture telescope if that’s what’s to hand.

On the night of 13/14 July, the GRS transits Jupiter’s central meridian at about 10.35pm BST (21:35 UT), but it’s barely 10 degrees up in the south-east at this time. However, it will remain visible for a couple of hours, as Jupiter climbs towards culmination, before it rotates out of view (Jupiter completes one rotation in just under ten hours). On 14/15 July, the GRS rotates into view at about 2.30am to 3am BST.

Filters to fight the seeing

Jupiter’s low altitude from mid-northern latitudes makes observing it more problematic than normal, owing to the prevalence of turbulent seeing so close to the horizon. Atmospheric dispersion leads to noticeable colour effects, such as red and blue fringing on planets, caused by our atmosphere essentially acting as a prism. A red filter (Wratten 23/25) will help reduce dispersion fringing (though the latter filter has only 15 per cent transmission, so might be better employed with a moderate- to large-aperture telescope). An Atmospheric Dispersion Corrector (ADC) is a great accessory too.

A blue or light-blue filter (Wratten 80A/82A) will enhance the contrast between the planet’s dusky belts and bright zones, while the visibility of dark markings is enhanced by a yellow or orange filter (such as Wratten 12/21). The latter filter is an especially good choice for observing the GRS.

Follow the Galilean moons

Jupiter is unique in the Solar System for its family of four large and bright Galilean moons: Io, Europa, Ganymede (the largest satellite in the Solar System, with a diameter of 5,268 kilometres [3,273 miles]) and Callisto. All can be seen through 10 x 50 binoculars. Following their eternal dance around their parent is a rewarding aspect of observing the giant planet, as they, together with their jet-black shadow, pass in front of the planet and at other times disappear behind and reappear from behind Jupiter (occultation) or move in and out of its massive shadow (eclipse).

The satellites move from east to west across the face of the planet and west to east behind it. After conjunction and before opposition, Jupiter’s shadow is cast to the west and shadow transits precedes transits, while eclipses happen before occultations. After opposition, the order is reversed.

Perhaps the most interesting of all the Galilean phenomena is watching the black shadows of the moons move across Jupiter’s face, though it’s much tougher to spot the moons themselves against the planet’s bright disc. A fascinating consequence of opposition is that a moon and its shadow can lie very close together, with occasionally the moon occulting its own shadow. On the night of 15/16 July, shortly after 3am BST (02:00 UT), Io and its shadow, seen very close together, will have just started a transit (see the graphic here). A 150mm telescope should be sufficient aperture to glimpse Io’s shadow in any fleeting moments of steadier seeing.

On 13/14 July at around 1am BST, Ganymede reappears from behind Jupiter’s eastern (following) limb.

As soon as Jupiter is observable on the night of 13/14 July, a pair of binoculars will show only three Galilean moons Io and Europa lie roughly equidistant from the planet, to the east and west (left and right, through binoculars), respectively, while Callisto lies some way west of Jupiter. Ganymede is hidden behind the giant planet, after disappearing into Jupiter’s shadow at 9.36pm BST (20.36 UT). It’s a shame that this event is not observable from UK shores, but Jupiter is barely above the horizon, having not long risen.

At this close to opposition (which occurs about 12 hours later), Jupiter’s giant shadow falls almost directly behind the planet, leaving an extremely thin sliver of shadow hugging the planet’s western (preceding) limb, which Ganymede gradually disappears into. See the graphic here showing the positions of the moons when Ganymede reappears at Jupiter’s eastern limb at around 1am. Obviously, the majority of eclipse events throughout the year occur when Jupiter is some way from opposition, so a moon will be seen to disappear in eclipse when it lies well away from Jupiter’s limb. Jupiter’s shadow falls increasing further westwards (or eastwards after opposition) from the limb the further the planet is from opposition.

On 14/15 July, all four Galilean moons can be seen throughout the night through a pair of binoculars and a small telescope. This is their orientation at 1am BST.

On the following night, 14/15 July, all the moons will be visible for the entire night. There’s no end to the observational fun that can be had following Jupiter’s Galilean satellites. Astronomy Now has monthly listings of those Galilean moon events that are visible from UK shores.

Despite Jupiter’s less-than-ideal observing circumstances at this year’s opposition, there’s still so much that can be seen by a determined observer. However, Jupiter is still a beautiful sight if all you want to do is gaze at it out of your window.

Our July issue features a complete guide to what’s up in the night sky this month including how to observe Jupiter. Get your copy in the shops or order online for home delivery in print or digital download.


Saw Jupiter in the day time

I have never tried to see a planet in the day, but knowing that Jupiter was very near the moon today and tonight, I thought I would give it a try. I took my 20 x 80's out around 7:00, WAY before the sky starts getting near dark. The sky was actually very light blue, almost like the middle of the day. But I easily saw Jupiter about 3 moon lengths below the moon, a little to the right.

#2 AstroChampion

#3 kellyvictoria

yes, it is exactly where you describe. easily visible also with10x50 Nikons.

Edited by kellyvictoria, 09 August 2019 - 07:12 PM.

#4 Jond105

Thank you for posting this. Just brought out my 120ED and an ES82 30mm and could get both in the same FOV.

#5 orangeusa

#6 Jim1804

#7 MDB

Thank for posting. Easily visible even in light overcast with Leica 10 x 42's and Sun doesn't set here for another 45 minutes.

#8 Ken Watts

Just stepped outside at 7: 00. Waited til 7:04 for the high clouds to pass, there was Jupiter! Thanks for the heads up!

#9 Stardust Dave

Didn't try with bino's . Picked up Jupiter in my grab & go 4.5" ballscope.

Could not make out Jupiter's moons at 50X, high clouds were starting to interfere.

Sun was still 20 degree above the horizon. A quick look then got clouded out.

#10 sbpb28314

Thanks for the heads up guys! I got some great views of the moon and put my new moon map to good use but thought my eyes/equipment weren't good enough to find Jupiter. Nope, just didn't look far enough. Saw a little white blotch with the binos. Couldn't get a crisp view of it with my scope because of all that shimmering heat but I got at least a faint smudge of one of the bands. That was way more fun than I've had all day!

#11 sg6

At an open day here one person's trick is to aim a scope at a bright star during the day - scope has the system to aim it fairly accurately to any point in the sky and so let people see a star during the day. Just need a clear sky and a suitably bright star.

This year it was Aldebaren in late March. Clouds lifted about 13:00 and we had people queing to have a look, went on for the rest of the afternoon and finally closed down around 16:30. Even the slight orange color of Alderbaren came through visually.

Great fun and you get lots of questions, and no worries about flash photography and night vison as the sun really wipes that out.

#12 chrysalis

On 10-27-88 without optical aid, I saw Venus (near farthest elongation), Jupiter (close to the moon), and Mars (near opposition) all during the daytime (well the sun had just risen or was about to set, but I'm counting it!)

#13 grif 678

Cool, could you see any of its moons?

No, the sky was just a little hazy, maybe that is why I did not see the moons, or probably just because they were too small through binocs to see in the day.

#14 RRMichigan

I have never tried to see a planet in the day, but knowing that Jupiter was very near the moon today and tonight, I thought I would give it a try. I took my 20 x 80's out around 7:00, WAY before the sky starts getting near dark. The sky was actually very light blue, almost like the middle of the day. But I easily saw Jupiter about 3 moon lengths below the moon, a little to the right.

Viewing the planets Venus (can be seen in broad daylight with just your eyes), Jupiter, Saturn and Mars a little before dark is always a great way to avoid mosquitoes and other bugs that come out in force later after the sun sets. Also, I have noticed that during summer months, the planetary views seem somehow clearer and less blurred than in darkness. Not sure if that is related to preceding the temperature drop that leads toward the dewpoint which affects both the air and your optics, but I suspect that or something similar is the reason. Recently (July) I had viewed both Jupiter and Saturn while still light, but for the fact that they were both rising in the southeast an hour or so before darkness began and that was the only unobstructed view I had in which to view them (my entire southern view from my backyard is blocked by a slew of 80 ft tall Chinese Elms in my neighbor's yard). Otherwise, I spend my time playing peek-a-boo thru holes in the leaves/branches and get a 1 minute view if lucky.


Captured my first image of Jupiter last night.

Amazing that you managed to do this from a cell phone. I know the other equipment helped. This is a great shot.

How much does all that stuff cost? Iɽ love to be able to see planets with this clarity.

I have no idea what any of this means, but i like your picture

You can change these settings on the Galaxy phone?

But seriously, if you expose for Jupiter, you won't see any moons. If you expose for the moons, Jupiter is a giant white smudge.

That’s really cool. Can’t wait till I can do stuff like this.

It takes some money, patience, lots of reading and learning, and even more patience.

Great! Mine was just a blurry white dot. The moon faired a little better. Took them using my birding scope and iPhone 6, as I didn’t have time to haul the telescope out.

"something something" looks like Uranus.

Jesus looks amazing, it’s wild that we can see that from so far away it really makes you think how big planets are and how much space there is.

I love to observe the sky, but I don't know if there are cheap telescopes.

You could start with binoculars if money is your biggest barrier.

Lovely shot. I just got a 130mm myself and I'm wondering how long of an exposure one could take at that magnification before object trailing becomes an issue?

The shutter speed is depending on the Focal length, not the opening. Divide 500/Focal length and this will give you the number of seconds for your exposure before star trails will be an issue


What was that galaxy(?) that I saw near Mars last night?

Last night, early morning of Jun 9 actually, I was viewing Mars at 200x when I noticed a faint elongated smudge near it (same field of view). How do I find out what that was? I've looking online for some charts but cannot find any chart that's detailed enough. I'm 80% certain it was a galaxy. But which one? NGC.

#2 Jim Davis

It wouldn't have been too far from NGC 5605.

Edit: Forget that, I set the date wrong.

Edited by Jim Davis, 09 June 2018 - 01:14 PM.

#3 Creedence

SkySafari would show you Mars' position in the sky at a specific time. I turned it back to 4:30 am, and it is somewhat close to NGC 6903 (nearly 12th mag).

There's also an app called Star Chart I found on the iTunes Store that does the same thing, and is free.

#4 Special Ed

What is the FOV of your scope at 200x? And the date and time UT.

Edited by Special Ed, 09 June 2018 - 02:45 PM.

#5 starcruiser

I was using a C8 and a William Optics Binoviewer (review coming soon) with the supplied 20mm (66 degree) eyepieces and the included 1.6 barlow. Nominal mag is 160x, but more like 200x in my estimation. Date: Jun 9, Time: *about* 0800 UTC (more or less). I should have made note of precise time, I forgot how fast planets actually move but both of them were in the same field of view for at least half an hour with no noticeable change of position. Then I went back inside to research some charts and went to bed.

#6 Tony Flanders

Last night, early morning of Jun 9 actually, I was viewing Mars at 200x when I noticed a faint elongated smudge near it (same field of view). How do I find out what that was?

Maybe a ghost reflection? There were no bright galaxies anywhere near Mars, and seeing a faint galaxy while blinded by magnitude -1.4 Mars seems utterly out of the question.

#7 starcruiser

Maybe a ghost reflection? There were no bright galaxies anywhere near Mars, and seeing a faint galaxy while blinded by magnitude -1.4 Mars seems utterly out of the question.

A ghost reflection is what I initially thought. So I panned the scope around to see if it would displace slightly relative to Mars and it didn't. It wasn't there last week. And I didn't see any ghost reflections like that when I was looking at Saturn or Jupiter (with same WO bino). It didn't look like a ghost reflection at all but it looked a lot like the familiar "smudge of light". But I won't rule it out so next chance of a clear sky, I'll check again.

#8 pjsmith_6198

I was looking in interstellarum Deep Sky Atlas and Mars would have been very near the galaxies ESO 597-26 and ESO 597-23. Those are pretty faint but interstellarum's key showed them visible in a 12 inch scope. Maybe their surface brightness is high enough for you to pick them up at 200x.

I checked where comet C/2016 M1 PANSTARRS was in case you were seeing that but that is in Sagittarius near M54. It would have been a two in the view. It will be "two in the view" close foe another day.

Maybe you were looking at Comet C/2018 Starcruiser.

#9 Special Ed

Your FOV is probably no more than 30 arcseconds. I checked my copy of Starry Nights Pro and there were noo objects you could have seen at 200x in that field.