? about nasa and hubble

Ok OK this might sound really dumb, but hubble can see really far out into space why cant they turn the damn thing to stars in our own galaxy ? to find a planet with life on it? i mean with all the tech it has onboard

[edit on 16-8-2005 by semperfi221]

A telescopes pourpose is NOT MAGNIFICATION The hubble space telescope can magnify about the same as my 10 inch dobsion backyard telescope.

The reason it is so much more effective is because it is in space and can focus on an object for days without atmosphere interference. Ever looked down a hot road on a summer day to see the wavy lines of distorted light? Thats why stars twinkle too because od different tempatures in the air. In space there is no air so the hubble is free form atmospheric distortion. Also on earth you can only photograph an object for at mas 11 hours. In space you dont have to worry about day so you can keep a camera exposure open for days or weeks.

The human eye process light on a constant basis. THe hubble and all telescopes focus of verry faint things. most un detectable by the human eye. In photography the camera lense can stay open and over time light filters in. THe longer you have a camera shutter open the more light you collect and the brighter the immage. Telescopes are about mirror size so you can colelct more light to see fainter objects. The hubble's cameras can focus for days or weeks on objects letting that light filiter in and we can see the faintest of things.

Ever taken a picture only to get a blank white picture? thats because it was over exposed or the shutter was open too long and let in too much light.

We cannot focus on other planets because they are so close to their parent stars it washes it out and we cannot magnify that geatly.

Understand?

That was a pretty good explanation, except that its wrong.

The Hubble is in LEO (low earth orbit), that same as the ISS, the Hubble is is a very poor place, the earth covers half of its view of the stars...and it orbits earth every 90 minutes, giving it 45 minutes to find its target and get some pics and info...thats it. If you want to spend more time on the target, you have to look at the target every-other 45 minutes.

This is one of the many of Hubbles downsides.

But Nasa isn't making the same mistake twice, the James Webb Space Telescope will be a million miles away from the earth...and not a few hundred like Hubble is.

I'm not saying your wrong Murcielago, Actually I don't doubt that your right. I'm just wondering how they did the Hubble Deep Feilds like that? I was always under the impression that the HDFs were doen over days exposure.

[edit on 16-8-2005 by Mizar]

Originally posted by Mizar
I'm not saying your wrong Murcielago, Actually I don't doubt that your right. I'm just wondering how they did the Hubble Deep Feilds like that?

I was always under the impression that the HDFs were doen over days exposure.

[edit on 16-8-2005 by Mizar]

Are you wondering how they get those amazing pictures that have stunning detail like this.?


The answer is a lot of time.

Those larger postcard type pics take quite awhile to make, Nasa takes a picture of just a small peice of it, but they take hundreds sometimes thousands of pictures, digitally of course, then put it all together back on earth...think of it like a puzzle.

But to answer the original question...
Because Hubble is old and it was never designed to be a planet finder, it was basically designed to see whats out there, and it did, thats why it needs to be retired.

The James Webb Telescope I talked about will be launched 2010-11.

But before that will be Kepler, its sole purpose will be to find planets.


Then down the road around 2020 or so, the TPF (Terrestrial Planet Finder) will come online, this thing will make the Hubble look like the Wal-mart special.

I was talkign about these immages...

www.spacetelescope.org...


Yeah as a veteran amature astronomer I pay close attention to thoes things, the new scopes that is!

same difference.

they do it the same way, they take a lot of pictures, of a large area, and piece them together...in fact, even the picture you posted needs 3 more pictures taken to complete that one, but more then likely that one is done, they probably photographed what they wanted and thats that, there really no point to try and make amazing moziacs on every finished picture.

That was a pretty good explanation, except that its wrong

I think Mizar is fairly close to correct. What did he state that is wrong?

Here is the page with some info.

hubble.nasa.gov...

Hubble was pointed at the same patch of sky for several cumulative days and took long exposures. Scientist were surprised to find a bewildering assortment of at least 10,000 galaxies at various stages of evolution.

TheMesh

I dont like to repeat myself.

Just read more closely what he wrote and what I wrote.

aug...ok, The Hubble is in LEO orbit, its phisically impossable to view on spot for much longer then 45 minutes, because it orbits so close to the earth.....hence why we can send astraunats to fix it every few years.

Hubble Can look at the same spot for weeks if they so desire, but they cant just keep it focused on it and thats that, they have to re-find it every 45 minutes, and take some more pics, those huge mosiacs can take several days, or even weeks.

get it?

Pretty much everything that we've sent into space is in low orbit. Except the voyager and galileo sataleittes and others we've sent to other planets. The reason it doesn't magnify on nearby stars and planets is probably because it will be a pretty rubbish picture, as it's able to see a books pages perfectly from where it's orbiting us. So imagine a 10x10 picture of a nearby planet. Exciting. Hubble is used for deep space pictures. Look on the NASA site for other sataleittes.

Well in actuality my response was noy wrong, it just was missing one peice of information. Everything in my post still holds true.

Thanks for clearing that up Murcielago. I never made the connection that Hubble was in low earth orbit. Even after that time I saw it thatnks to Skies above.

Makes perfect sense.

I dont like to repeat myself.

Just read more closely what he wrote and what I wrote.

The Hubble is in LEO orbit, its phisically impossable to view on spot for much longer then 45 minutes, because it orbits so close to the earth

Yes, I read it clearly, that is why I asked. OK Murci, since you are so adamant. Let me put it in clearer terms. Mizar is the one correct, and you are the one that lowered the boom on him yet is wrong. Seems to be a pattern.

The fact that Hubble is in orbit around the earth and cannot spot onto any area for more than 45 minutes has nothing to do with the fact that it cannot distinguish another planet from its sun. It does not have enough resolution due to the magnification power of the optics, as well as the discernment of the EM detectors. We have all seen the time delay pictures of the first planets detected, and it is accomplished due to the indirect effect of the gravity making the star wobble, as well as the shadow cast by the planet passing in front of the sun. This is due to the dim amount of light coming from the planet with respect to that star, and our lack of skill in detecting that light.

The Hubble can point with enough resolution to take extended exposures even though it is orbiting. There is a slight drawback due to the gravity of the earth interfering with the precision of the gyroscope pointing mechanisms. But it is negligible. The real reason the orbit is a bad thing, is that there is a wash of EM radiation closer to the earth coming from the sun, earth, and moon, which washes out the intruments, and also heats the Hubble, causing it to glow upon itself, and disperse even more radiation, that it in turn detects. The JWST has a mirror 2.5 times the size of the Hubble, and it also has much better EM detectors, as well as it being further out of range of the interference of the earth, moon, and sun.

But all objects, including telescopes, also emit infrared light. To avoid swamping the very faint astronomical signals with radiation from the telescope, the telescope and its instruments must be very cold. Therefore, JWST has a large shield that blocks the light from the Sun, Earth, and Moon, which otherwise would heat up the telescope, and interfere with the observations. To have this work, JWST must be in an orbit where all three of these objects are in about the same direction.

In order to do this, JWST will have a much larger primary mirror than Hubble (2.5 times larger in diameter, or about 6 times larger in area), giving it much more light gathering power. It also will have better infrared instruments than Hubble, allowing it to see the formation of stars and galaxies (see below). Finally, JWST will operate much farther from Earth, where operations are simpler, and where giving the telescope a stable pointing is easier than with the Earth-orbiting Hubble

JWST is designed to discover and study the first stars and galaxies that formed in the early Universe. To see these faint objects, it must be able to detect things that are ten billion times as faint as the faintest stars visible without a telescope. This is 10 to 100 times fainter than Hubble can see.

www.jwst.nasa.gov...

Nice speaking with you again.

TheMesh

TheMesh.....judging from you last post, I think i'll just refer to as TheAss.

TheAss
The fact that Hubble is in orbit around the earth and cannot spot onto any area for more than 45 minutes has nothing to do with the fact that it cannot distinguish another planet from its sun.

That was in response to Mizar, it had to do with deep field images. and had nothing to do with semperfi221 question.

and the rest of your post just seemed to be talking about the JWST...not sure where you were going there, I allready know everything about it.

The problem is really just a matter of physics. Hubble's primary mirror is too small to resolve a planet orbiting another star. The theoretical resolution in arcseconds, the Dawes Limit, can be given by the formula 4.58/D, where D is the diameter of the primary optic in inches. The Hubble's main mirror is about 8 feet in diameter, which is 96 inches. This equates to a Dawes Limit of about .0477 arcseconds for the Hubble. It is possible to detect objects smaller than this, but not to cleanly resolve them.

Most stars themselves have apparent diameters smaller than the Hubble's Dawes Limit, so its basically impossible for the telescope to resolve the even smaller planet from its parent star. The problem is compounded by the fact that light production is not an equal partnership between the star and planet, as the star's light completely overwhelms the light reflected by the planet. Star and planet appear simply as a single star to the Hubble as a result. You would need an interferometer (basically, you'd need another Hubble) to cancel out the star's light to detect any orbiting planet and even then, there are certainly no guarantees since the orbiting planet will likely be much smaller than the Hubble can cleanly resolve.

Originally posted by mashup
as it's able to see a books pages perfectly from where it's orbiting us.

Nope, it can't observe earth's surface because our planet rotates too fast.
It's same effect what you see when you take photo of moving object with too long exposure.


Murcielago, long exposure photos are made by stacking separate shorter exposure photos.
Amateurs use it to achieve magnificent results without expensive equipment.
With webcams taking many pics in second it can be also used to get smaller details by selecting those pics when atmosphere was calm and then combining those. (works for bright objects like planets when very short exposures are possible)
ccdastrophotography.com...
velatron.com...