URANUS 2014 & 2015
Uranus is the butt of many corny jokes (like that one! J) but resolving anything on this faraway planet is one of the biggest challenges for amateurs & their equipment.
Considering that this planet is 2.5
billion kms away at its' closest (over twice the distance to Saturn) &
much smaller (although still massive when compared to the Earth) it is not
surprising that it is so hard to image with any visible outcomes other than
as a pal&, blue-green disk!
One of the surprising aspects about Uranus is that this planet is really an "odd-ball" when it comes to its orientation...all the other planets & the Sun revolve/rotate in an "upright" manner, their North & South Poles are all similarly orientated, ie if we could view our Solar System from afar all the North Poles would be pointing "up" & all the South Poles pointing "down" so to speak. J
Not so with Uranus, this cold, distant "Ice Giant" has its' North & South Poles at approximately 90 degrees orientation to the rest of the planets in the Solar System...it appears as if it is laying on its' side and instead of seeing it from Earth as revolving/rotating from left to right as a disk in telescopes, it appears somewhat like those Polar projections in the Saturn section, where we look down upon the North Pole to a certain extent..!
It is called a
"Ice Giant" because although like Jupiter & Saturn…Uranus &
Neptune they are mainly made up of gases that become ever more highly
compressed towards the interior of these planets, but these “Ice Giants” do
not have the heavy mantle of hydrogen & helium that Jupiter & Saturn
possess…they are composed mainly from oxygen, nitrogen, carbon & sulphur
with a thick layer of water & ammonia ice inside them…& a rocky core.
Note: Some images on this page are “clickable” and will
open up as “full scale images” in a new tab.
A specific type of filter is required to successfully reveal the clouds bands on Uranus' surface, this "surface" being somewhat similar to the Gas Giants, in actual fact the tops of the these planets are composed of clouds of gas...
This "special filter" is termed an "RG-longpass" or iR610nm filter because it only allows light to pass through it that has elements of the light spectrum that include portions of green, red & near-infrared light: these are the wavelengths reflected back from Uranus that allows us to pick up certain features on the planet best.
Light is part of the "electro-magnetic" spectrum that includes X-rays, visible light, radio & TV waves etc: here is a graphic display of this.
Light's "wavelength" (the length from the top of one of those "squiggles" to the next top) is measured in "nano-meters" or "billionths of a meter" - pretty tiny!!! J
You can see from this chart/display that the 610nm filter used for Uranus is basically letting light through from the "yellow-orange" part of the light spectrum...
This is our first attempt to create an
image of Uranus that approximates
the view of this planet looking through a telescope – but this is always
going to be a difficult & contested representation for a number of
reasons…the detail displayed here relies upon the fact that we use various
infrared filters to capture the banding on Uranus’ disk & combine these
infrared images/captures with a “straight” colour-capture (rgb) from the
ASI224MC colour camera.
all these images will usually result in a composite image where the planet’s
dark & light bands appear overly-exaggerated - like striped confectionary
– or else patently “false” in other ways.
To achieve the image shown here necessitated using
colour values & manipulating their strength (saturation) to arrive at
what we considered to be the best outcome: the image is not “false” as such but relies on light that the human
eyes cannot normally detect to provide what is probably best described as an
“enhanced” version of what we might see through a telescope eyepiece - on an
extremely good night! J
is an enlarged version: in the text above I give a (very) brief description
of how I processed them, adjusting the colour values & strengths - but
making no alteration to the image data itself.
a slightly more detailed description, I relied upon the calibrated colour
image (or “true colour”) representation of Uranus we took as part of the
image-captures in that night’s session, taking note of several experienced
imagers’ & sketchers & other observers comments re the
“best-calibrated” colour outcome for this particular image.
it is a subjective outcome but one which I think does this distant planet
will notice these 2 images above are very different to the “false colour”
images I have created for the 2014 Uranus images (further down this page) –
in those images colour was simply applied to the black & white images we
captured in infrared & I paid too much attention to the notion of Uranus
being “green.” (Hopefully!) we all live, learn & improve..! J
image on the right here (taken on a different night) gives a good idea
of how we arrived at the colouration
for the preceding images: this is another “calibrated” straight-forward
colour capture of Uranus. (ie, no iR filters)
The smaller image outlined in red is an image from a
computor program which shows the orientation of Uranus & the position of
several of its major moons for anytime of the year: this enables us to match
our own images to this program’s views because depending upon how our camera
is placed in our telescope etc alters our own view or orientation – somewhat
like knowing how we took a photo of some scenery - & knowing where we
stood when we took the photo…except with a telescope we could be taking the
image “upside down” & would not know it unless we had this program to
help us get the proper orientation! J
Actually, if you compare this image to the 2 above
it is “flipped over” or rotated 180 degrees in comparison – we know this from
the position of the moons in those images compared to their positions in this
image. (the moons are not shown in
those first 2 images)
The above multi-image composition
represents the better captures for Uranus in 2015.
(2015) apparition (season) is over as far as Uranus is concerned so I thought
it worthwhile to make this composite overview of “Uranus in 2015.” ;)
The bottom image above is a North Polar projection –
this is one of those WinJUPOS software images where we feed a “normal” image
into the program & WinJUPOS creates a view that simulates the appearance
of the planet from above the polar region…you will also notice (along with
the Universal Times -UT- & dates of each image, the specific wavelength
of the infrared filters employed.
These Uranus images (17th
& 18th September 2015) are taken with the ASI224MC colour
camera using iR (infra-red) filters.
one uses a 685nm filter whilst the one immediately below used an iR610nm
filter: the 685nm filter restricts the amount of light through itself making
the image appear dimmer – this means that to get a proper exposure we have to
limit the number of frames to around 12.5 frames per second. (fps)
The benefit of this filter is that we can
(sometimes!) obtain slightly better contrast in the end-results to make the
cloud bands on Uranus stand out slightly more strongly, as well as reveal
slightly more tonal variation on the planet.
the comparison from an image taken the night before using the 610nm filter: there is slightly less
contrast in the cloud bands but you can see that we could obtain a 68%
exposure (histogram) & also 25 frames per second. (fps)
is because the 610nm filter lets more light through…however, often getting
more frames per second can compensate for the slightly lower contrast in the
images…so nothing is set in stone & is the reason why we might vary what
filters we use, as well as the exposure & frame-rate of the avi’s
(videos) we set in the camera to capture our planet images ;)
The first image from the 2015 apparition of Uranus in August -“apparition” being the term to describe when a planet emerges from the other side of the Sun & becomes visible in the early, pre-dawn morning sky. It progressively appears earlier each morning (& therefore further away from the rising Sun) until it is visible as soon as it is dark enough after Sunset. It continues its apparent motion across the sky until it becomes so close to the Sun that it is lost to view in the evening twilight & finally disappears behind the Sun – the end of another apparition! J
The above image
was taken with the new ASI224MC colour camera: as said in the “Latest Saturn
pics” section of this website this camera seems to be breaking all the old
preconceptions of colour cameras…it is so sensitive (along with low noise
qualities) that with an iR610nm filter (a specific type of infra-red filter
used to capture details on Uranus & Neptune) it easily picked up the
cloud bands displayed in this image – even on a night where seeing was not
really good & clouds kept on making imaging more difficult! We look
forward to seeing what might be possible on a really good night when imaging
Uranus…& also Neptune! J
Note: these Uranus images are what are termed “false colour images” -
they are captured as mono (black & white) images & the approximate
colour-appearance of the planet is added during processing. (see bottom
The first image here is the 2nd or 3rd attempt at imaging Uranus by us: by then we had worked out a way to focus, set the camera controls & also process the resulting video for best outcomes: there is very little available information on how to do these things & we found that what was available was totally unsatisfactory...so the ensuing results were a sense of real satisfaction for us..! J
In this image you can see 3 of Uranus faint moons - remembering that Uranus & its' moons are over 2.5 billion kilometres away!!!
You can see
some of the cloud bands that swirl around this planet & they also give an
indication of the "tilt" of this planet, with the North Pole
situated around the "10 o'clock" position on the disk.
This next Full Scale image, taken the night after the first one above is enlarged considerably in processing to assist viewing: there is a noticeable "fuzzy white spot" straight down from the top dead centre of the disk on the edge of the dark central band, just over a third of the way down
This is a large storm in Uranus' upper atmosphere & one of the features that amateur imagers who target this planet strive to capture when they are present.
This next image was taken on another night of good "seeing" (like the others - Uranus will not show anything but a greenish-blue disk - if that - in anything but good seeing!)
But on this night the sky "transparency" was also excellent - this "transparency" is the amount of haze/dust/pollen etc in the air & when the transparency is high it is like looking through an exceptionally clear window...as long as the other conditions mentioned (surface winds & jet-streams etc) are good. J
This meant that we could pick up all 5 major moons of Uranus - from left to right in the image they are Ariel, Miranda, Umbriel, Titania & Oberon. Of these Miranda is a real challenge & triumph to catch, because it is so faint!!! J
Finally here is an image composed of all the images of Uranus we captured during October 2014...our first month of targeting this distant world. Unfortunately the weather did not "play ball" for us after that & by December 2014 Uranus was beginning to be "lost" in the evening twilight & no longer able to be imaged.
By this I mean that when Uranus was highest in the sky (the best imaging time for any planet) the seasonal change from the approach of Summer meant there was still a lot of light in that part of the sky - because the Sun was beginning to set much later in the day... L