Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 5:35 pm
by Ann
Click to play embedded YouTube video.
Ann
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 5:40 pm
by hstarbuck
Nice rare shot, but not as rare as this........
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 7:01 pm
by Eldad
Funny, yesterday, in Peekskill, NY, I saw a twin-engined Constellation(?) (I've seen the four-engined kind, but rarely the two-engined kind), travelling west to east, at an altitude that lends itself to good, naked-eye observation. If only I had anticipated it. A large twin-engined plane transiting a waning gibbous moon a couple of weeks after the same type plane transits a waxing gibbous moon, completes the coincedence; one the flip-side of the other, plane-crossed waning gibbous here now; plane-crossed waxing gibbous way over there there then! How cool is that?
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 7:49 pm
by Corky
I must admit, at first I thought that this must be a faked photo and the good people at APOD had been duped. The photo looked too sharp and composed to be real. However, after some research and basic trigonometry, I have come to the conclusion that it is real. The calculated altitude of the plane in the photo is about 7,200 m, which is less than its maximum cruising altitude of 8,230 m. In addition, the amount of blur on the image is about 0.7 m, which is exactly what you would expect if the plane was travelling at its maximum cruising speed of 670 km/hr. Math to the rescue again! I doubt that anyone would put in that much effort to fake a photo. Nice shot!
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 8:11 pm
by neufer
Eldad wrote:
Funny, yesterday, in Peekskill, NY, I saw a twin-engined Constellation(?)
(I've seen the four-engined kind, but rarely the two-engined kind),
travelling west to east, at an altitude that lends itself to good, naked-eye observation.
Rather than a single vertical stabilizer, a twin tail has two. These are vertically arranged, and intersect or are mounted to the ends of the horizontal stabilizer. The Beechcraft Model 18 and many modern military aircraft such as the American F-14, F-15, and F/A-18 use this configuration. The F/A-18, F-22 Raptor, and F-35 Lightning II have tailfins that are canted outward, to the point that they have some authority as horizontal control surfaces; both aircraft are designed to deflect their rudders inward during takeoff to increase pitching moment.
Triple tail
A variation on the twin tail, it has three vertical stabilizers [e.g., four engine Boeing 314 & ClipperBreguet Deux-Ponts]. The best example of this configuration is the four engine Lockheed Constellation. On the Constellation it was done to give the airplane maximum vertical stabilizer area, but keep the overall height low enough so that it could fit into maintenance hangars.
Quadruple tail
A very unusual design can be seen on the E-2 Hawkeye, which has two additional vertical tails fixed to the horizontal stabilizer between the normal vertical twin-tail surfaces. This arrangement was chosen for the stringent size limitations of carrier-based aircraft.>>
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 8:48 pm
by hotspur
Hi All
Re photo of Bombadier Q400 passing moon (one day after first quarter).
Just a few notes on how I took the photo,as there seems some confusion of this forum.
Firstly its NOT a montage or fake!
I live 2 hours N.W of Brisbane,Queensland,Australia.Near the Blackbutt Range.
This aircraft fly's over our property everyday at 5.30 pm.I am very aware of it and its time.
Over many years I have obsevered it fly very close to first quarter moon,and sometimes through its disc.
As a astronomer,with a permanent roll off roof observatory,It became a challange for me to capture the image.
So I have set up many time before to capture this image-No luck involved-only 5P's of astrophotography
PRIOR-PREPARATION-PREVENTS-POOR-PERFORMANCE !
I used a Vixen 103ED refractor on Vixen GP mount using a Vixen SS2K tracking,and a Canon 450D cable release.on shot only.
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 9:16 pm
by neufer
Corky wrote:
The calculated altitude of the plane in the photo is about 7,200 m,
which is less than its maximum cruising altitude of 8,230 m.
I calculate an altitude of about 6,500 m (which gives it a little more leeway).
I calculate the distance to the ET Kuwahara bicycle at about 430 m
(; I'm not quite sure about its maximum cruising altitude).
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 9:50 pm
by emc
Hi Chris (hotspur), Thanks for posting… it is a cool image and I am sure we all appreciate your posting here. It’s icing on the cake to hear from the resource of the APOD.
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Wed Sep 29, 2010 11:48 pm
by Andy
Beautiful shot. I've only managed to view and sketch these kinds of shots. Good job, "Nerves-Of-Steel-Thomas"!!! -Andy
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 12:56 am
by Susanvb
Too much like Photoshop to work.
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 1:06 am
by ZenGrouch
Judging from the size of the Moon, the photograph was taken with a fairly powerful telephoto lens. For the plane to appear to be approximately the same size as the Moon, it would have to be quite a distance from the camera, therefore not flying slow enough for a take off or landing situation.
Now, I'm not accusing the photographer of trickery, and I could be very far off base and totally ignorant of the physics behind such a shot, but I'm of the belief that a 1/250th of an second exposure would show quite a bit more motion in the plane. Judging from the propellers in the photo, I'd have guessed a much faster exposure...
Looking forward to someone showing me the error of my logic. I'm not too old to learn.
<edit>
Sometimes I'm not so bright...
Guesstamating an airspeed of 300mph, the plane would travel ~21 inches in 1/250th of a second, which looks about right in the photo.
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 1:33 am
by Chris Peterson
ZenGrouch wrote:Guesstamating an airspeed of 300mph, the plane would travel ~21 inches in 1/250th of a second, which looks about right in the photo.
Looking at the angular size of the plane, and the wingspan and fuselage length specs, this aircraft is at an altitude of about 22,000 feet. If it is flying at 600 km/h, it will move 0.66 meters in 1/250s, or about 2% of its total length. That seems reasonable. In fact, since the plane is somewhat below its usual cruise altitude, it may also be going slower. In any case, though, the motion blur should be pretty small.
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 2:09 am
by neufer
Susanvb wrote:Too much like Photoshop to work.
Who would have bothered to stick in the vapor plumes?
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 2:59 am
by BMAONE23
Susanvb wrote:Too much like Photoshop to work.
The Moon has a diameter of 3476k and orbits at 384,400k from the Earth. At that distance, it covers 1/2 deg or 30'(minutes) of sky.
Looking at the image, The plane, per the tail design, is Qantas Air
.
The footprint of the airplane would make it a De Havilland Canada DHC-8-400 or Dash 8 which has a ceiling of 25,000' Qantas still flies these workhorses and has since the 70's
The DASH 8 has a wingspan of 93' and a body length of 107'.
The image depicts the wingspan covering approx 1/2 the lunar angular size or 15' (minutes) (1/4 degree)
At an altitude of 21,000', the wingspan of 93' would appear to have an angular size of 1/4 degree.
So it is a Qantas Air DASH 8 flying at 21,000' or 21,500' that happened to be traveling across the field of view of the moon at the time the image was taken,
well within operating design.
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 3:36 am
by neufer
BMAONE23 wrote:
So it is a Qantas Air DASH 8 flying at 21,000' or 21,500'
6500 m = 21,325'
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 3:52 am
by jhagerty@juno.com
bystander wrote:
neufer wrote:(The plane is obviously just a prop.)
It is not just a prop, it is a turbo prop.
It's a Saab 340, or one of that family, I believe. Nice airplanes. I rode one from Dallas to Waco and back. Holds 18 people and they have to arrange the passengers by size to make sure the larger ones are over the wing! Even better, you don't have to worry about that oxygen mask stuff since it flies under 10,000 ft (3.000 m).
- Jack
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 4:08 am
by neufer
jhagerty@juno.com wrote:
bystander wrote:
neufer wrote:(The plane is obviously just a prop.)
It is not just a prop, it is a turbo prop.
It's a Saab 340, or one of that family, I believe.
it flies under 10,000 ft (3.000 m).
Re: APOD: An Airplane in Front of the Moon (2010 Sep 29)
Posted: Thu Sep 30, 2010 11:40 am
by OzRattler
I just love how people are incapable of giving credit where credit is due!!! It is for real. You can check with QANTAS that they have a service that matches the details others have worked out using maths. Further, those who understand PhotoShop and its cousins - even those within Linux such as Blender - will know the tiny chance of getting the blurred exhaust correct.
As for the light - atmospheric diffusion. One thing that most people miss is how objects look in day to day life. Watch a plane fly by and it has lighting that is different to back ground - thanks to angles.
Lastly, the supporting paragraph is lame!!! How utterly RUDE to imply luck!?!?!?
Envy.............contagious for those with less talent. Sorry...but I am cross at some in this thread. Those that have seen the "light" (dare I say) are why I read this web site. Clever minds.
Have fun!
Rrrrrrrrrrrrrrrrrrrrrr
QUANTAS uncertainty
Posted: Thu Sep 30, 2010 12:48 pm
by neufer
Julian wrote:
Light reaching airplane does not match sun light reaching moon.
they seem to come from different directions.
<<Major-General Sir Thomas Makdougall Brisbane, 1st Baronet (23 July 1773 – 27 January 1860) was a British soldier, colonial Governor and astronomer. Brisbane was born at Brisbane House in Noddsdale, near Largs in Ayrshire, Scotland, the son of Sir Thomas Brisbane and Dame Eleanora Brisbane. He was educated in astronomy and mathematics at the University of Edinburgh. Brisbane was a keen astronomer throughout his career. He had an observatory built at his ancestral home in 1808. From this observatory he was able to contribute to the advances in navigation which took place over the next hundred years. He took all his instruments and two astronomical assistants, Carl Ludwig Christian Rümker and James Dunlop to New South Wales with him, first properly equipped Australian observatory at Parramatta. While waiting for Macquarie to complete his final arrangements, interested himself in making astronomical observations. In 1822 he established an observatory at Parramatta west of Sydney. He was the first patron of science in Australia, and as such was eulogized by Sir John Herschel when he presented Brisbane with the gold medal of the Royal Astronomical Society in 1828.
In 1821 Brisbane was appointed Governor of New South Wales, a post he held until 1825. In 1823 Brisbane sent Lieutenant John Oxley to find a new site for convicts who were repeat offenders. Oxley discovered a large river flowing into Moreton Bay. A year later, the first convicts arrived at Moreton Bay. Brisbane visited the settlement in 1826. Oxley suggested that both the river and the settlement be named after Brisbane.
When Brisbane returned to Scotland he continued his studies and built a further observatory on his wife's estate, Makerstoun, near Kelso in the Borders. He was a member of the Royal Society of Edinburgh and received their Keith Prize in 1848. He was elected president in 1833 after the death of Sir Walter Scott, and in the following year acted as president of the British Association for the Advancement of Science. He founded a gold medal for the encouragement of scientific research to be awarded by the Royal Society of Edinburgh. He published The Brisbane Catalogue of 7,385 stars of the Southern Hemisphere in 1835. The Observatory was used until 1855.>>