An image of Comet Ison or is it really a comet?

reply to post by NeoParadigm


Know what I think?

They did those "three exposures" just for the epicness of it. First exposure of that steak. Then that bright dot. Then the next one streak.

They planned it.

ok earth's circumference - 40,075 km

hubble orbit speed - 8km per second

in 43 mins, hubble covers 20,640km

only half the circumference of the earth.. and not quite half because the orbit circumference is larger than earth's surface circumference. so basically.. hubble has moved only from one extreme to the other (from right side to left side).

this during the earth moving at approx 108,000kmph around the sun

radius distance from earth to sun = 149,597,890
earth's orbital Circumference = 939,474,749

the fraction is just too small to create a change in direction from what i understand. 108,000/939,474,749 - and i gave it the whole hr as opposed to 43 minutes.. still too small in my view.

reply to post by filledcup


How can you come to that conclusion without even factoring in the distance to ISON?

reply to post by filledcup


Others will try to explain to you. It is apparent motion.

Originally posted by NeoParadigm
reply to post by filledcup

 

How can you come to that conclusion without even factoring in the distance to ISON?

because i just read an article which said ison just flew round the back of the sun. my estimate distance of ison using approximate figures is the radius of earth to the sun.

now i need hubble's direction of travel during the 43 mins to compare relatively with ison's direction of travel in space. from there i will be able to see through hubble's eyes as it moves observing the comet on it's path.

reply to post by Deaf Alien


The fact that it appears as streak-dot-streak is also because of angle change.

It was explained by Nataylor

Because of the HST's motion around the Earth, you get this scalloped path, where the comet appears to move less at "points" in the path, and then speeds up as it swoops to the next point. That's exactly what you see in the image. One long streak where the comet was moving quickly relative tot he background, more of a single point where the comet was near the tip of the path, and then another long streak as it swooped on on the next point. As you can see from the time stamps, the 2,300 seconds (38 minutes and 20 seconds) total for the exposures nicely matches up with the shapes we see in the exposures.

reply to post by filledcup


Fair enough, it is not apparent from your comment that you have factored this in though.

Originally posted by nataylor
reply to post by filledcup

 

Here's an animation showing the HST's movement over 90 minutes. Each step is 5 minutes.

In 43 minutes, it travels about half of the indicated path.

Or exactly the line needed for a triangle shape to be produced when overlayed...

This graphic is exceptional, it prooves in the 43 minutes in which the comet was photgraphed, Hubble created the EXACT triangle osilation needed to observe the OP image.

/thread

This is one of the best graphics I have seen on ATS at explaining perfectly the image in question.

Im going to post a reply for a video explaining the parallax in the Hubble Images..

DarkSkyWatcher74 : Parallax is displacement of the apparent position of an object viewed from to lines of sight. In order for this to be parallax you require 1 object (ISON) as seen from 2 lines of sight and measures the angle of inclination between those 2 lines, Hubble is only 1 line of sight, this could not and can not be parallax the parameters are just not there

reply to post by NeoParadigm


Yes I know but apparently this guy (www.abovetopsecret.com...) doesn't understand it yet.

I agree it is hard to visualize it.

Originally posted by ElohimJD


This graphic is exceptional, it prooves in the 43 minutes in which the comet was photgraphed, Hubble created the EXACT triangle osilation needed to observe the OP image.

/thread

This is one of the best graphics I have seen on ATS at explaining perfectly the image in question.

the problem is the loss in synchronicity. there seems to be a 5-15 minute delay in the crescent. also the length of the line in relation to earth's size may be 'out-of-scale' making the line appear longer than it actually is. the graphic even appears to represent hubble making a full revolution of the earth.. which my calculations show would take about 2 hrs+.

i also think, that u can draw any shape using that image coming from the hubble as it revolves around the earth. not just a crescent.. a squiggly s-shape, straight lines.. anything. that's why i wanted to see the line(path of orbit during the 43 mins) drawn on a still image of the earth's surface.

reply to post by NeoParadigm


I gave him examples but oh well

reply to post by filledcup


What are you trying to say?

Originally posted by NeoParadigm
reply to post by filledcup

 

Fair enough, it is not apparent from your comment that you have factored this in though.

edit on 20-8-2013 by NeoParadigm because: (no reason given)

lol ok.. sometimes i forget to show my working for common sense. sort of took it as a given.

Originally posted by Deaf Alien
reply to post by filledcup

 

What are you trying to say?

ok let's go one at a time.

first.. the reason the graphic(gif image) can be considered misleading in the first case, is that it shows as though the hubble has made a full revolution around the earth in the time represented. but that's too fast for the hubble to circle the entire earth in 1 hr.

unless it's travelling in counter rotation? giving it a double-speed effect or 16km per second?

reply to post by filledcup


We're talking about very small angles here. In the photo of ISON with the three streaks, the start and end point are only 0.00179° apart.

If you have an isolseles triangle with and angle of 0.00179° at one point, the other two angles will be 89.999105°. With a side length of 646,377,000 km (ISON's distance from Earth), as shown in the diagram below, we can solve for side X:



Side X is going to be 20,194 km. So to get the a separation of 0.00179°, Hubble only needs to move a minimum of 20,194 km. As even you've shown, it clearly does move at least that much.

Originally posted by Yummy Freelunch
Im going to post a reply for a video explaining the parallax in the Hubble Images..

DarkSkyWatcher74 : Parallax is displacement of the apparent position of an object viewed from to lines of sight. In order for this to be parallax you require 1 object (ISON) as seen from 2 lines of sight and measures the angle of inclination between those 2 lines, Hubble is only 1 line of sight, this could not and can not be parallax the parameters are just not there

Parallax is not what causes the angle change in ISON's path, and noone is claiming it is. Hubble's movement is the cause for that.

Parralax only explains why the stars don't appear to have moved in the pic, unlike ISON.

The reason is that stars are much much further away.

sigh.....

Originally posted by filledcup
the graphic even appears to represent hubble making a full revolution of the earth.. which my calculations show would take about 2 hrs+.

Your calculations are wrong:

en.wikipedia.org...

Orbit period: 96–97 minutes (14–15 periods per day)

reply to post by nataylor


as u said the angle is very small.. and i agree all the way. but how does such a small movement account for an almost 90 degree change in direction by the comet? hubble has covered only half of the earth during this time.

Originally posted by nataylor

Originally posted by filledcup
the graphic even appears to represent hubble making a full revolution of the earth.. which my calculations show would take about 2 hrs+.

Your calculations are wrong:

en.wikipedia.org...

Orbit period: 96–97 minutes (14–15 periods per day)

that's still more than twice 43 minutes!

and my calculations arent really wrong.. wikipedia has used 7.5km per second, while i used a rounded 8km per second in my calculation. im actually trying to help the hubble here lol