I Don't Get It?

Question

How come the Hubble Space Telescope, being capable, can photograph objects billions of lightyears away from Earth with great clarity and detail (stars, mok globules, etc.), while it can only get 'this close' when photographing Mars, or Europa or other 'much closer' objects in our own backyard?

Why even the need to send orbiting crafts to these nearby objects to get an - even then - not so sharp images?

Or maybe NASA is not providing the public with such 'ala google-earth' photos of our neighboring planets?

(*head scratch*) Refractive problems, hyperopia perhaps?

Answer 1

The objects that are being imaged by Hubble from billions of light years away are also hundreds of thousands, or millions of light years across. That it how it can pick out really remote galaxies. However these are still only a bright patch on the image. So the ratio of size to distance is like 1 in a thousand to 1 in twenty thousand. It cannot pick out individual stars at such distances.

Small details on say Mars are too small in relation to its distance for even the HST to resolve. Of course large features like big craters, the big volcanoes, wide plains and rough terrain are easily seen. But the surface of Mars has been thoroughly mapped by orbiters which can photograph rocks only several feet across and it is being explored by surface robots. Mars is now more of an interest to geologists, not astronomers.

HST images of Mars can be seen in the Wikipedia article on Mars and If you hunted through NASA sites I'm sure you could find a lot more.

Telescope time is limited and you don't waste it by looking at the house next door when you can walk up and take samples of the paintwork or at least lean on the fence and look.

Astronomers are generally not interested in the planets where things are comparatively quiet, preferring to study energetic events that occurred long ago early in the history of the Universe, that means very remote objects.

The nearest large galaxy is Andromeda and it is "only" about 2.5 million light years away, but about 250,000 light years across so it is visible even to the naked eye. If something interesting happens in Andromeda though, you can bet that the HST and other non-NASA space telescopes will be pointed at it.

Answer 2

I had to take Statistics last year. It was like Greek to me. I was so scared I'd fail. I spent every day pouring over the material absorbing none of it. So I took a break. I didn't even open a book for several days. At the last minute, when the assignment was due, I 'bit the bullet' and just did it. I got an A. The point is, if something is frustrating you, get away from it for a while. Give your poor noggin a break. I know it sounds 'fluffy' but if you believe in yourself strongly I think you can do anything.

Answer 3

The objects that the Hubble takes pictures of are indeed very far away. They are also extraordinarily large. It is only their distance that makes them seem small.
The positioning of the lenses and mirrors in relation to the array of sensors that converts the light into an electronic signal require more precision in positioning for objects near the Earth.
The Objects near the Earth are moving relative to the Hubble satellite in relatively complex motions compared to the objects Billions of light years away. It therefore is harder to keep the image of the close objects stationary on the sensors.
The objects near the Earth are exceptionally brighter than the objects Billions of light years away due to the inverse square law. The sensors that would work for near objects would not be good for the relatively dim objects far away.
There are probably a lot more problems as well. These are just the first that came to mind.

Answer 4

Planets are tiny, galaxies are huge. The apparent size of the various objects in the sky is given in degrees, minutes and seconds of arc. 60 seconds make one minute, sixty minutes make one degree, and 360 degrees make a complete circle around the sky. The Moon, as an example, subtends an angle of about 30 minutes of arc.

Pluto, as an example, has a diameter of about 2,400km, and is at its closest about 7,200,000,000km from Earth. Using simple trigonometry you can calculate that it subtends an angle in the sky of about 0.07 seconds of arc, or about 1/26,000 the apparent size of the Moon.

Galaxies vary in size, but let's take our own galaxy as a typical example. It's 100,000 light years across. The furthest object observed so far is about 13,000,000,000 light years away. So, using trigonometry again a 100,000 light year diameter galaxy located 13,000,000,000 light years away subtends an angle of about 15.9 seconds of arc, only 1/113 the apparent size of the Moon, and over 200 times wider than Pluto appears. That's an extreme example. Most galaxies and nebulae are considerably closer than that, and therefore appear correspondingly larger. Some nebulae actually appear much larger than the Moon does from here. Because they are so faint we can't see them with the unaided eye and need optical instruments like the Hubble telescope to see them.

Telecopes are used not only to show things that are too small to be seen, but also things that are large but too faint to be seen.

So, Pluto and the other planets and Moons are close but tiny, while galaxies are distant but vast.

Answer 5

The things Hubble is imaging are HUGE in comparison to the planets. Details of a 100,000 lightyear in diameter galaxy a few billlion light years away aren't as difficult to image as rocks the size of a car on a planet millions of miles away.
Take the Pillars of Creation in the Eable Nebula - they are a dozen light years long. That's a lot more area to image than a planet.

Answer 6

It these planets could light up and exist at high temperatures Hubble could image them better.
Stars are just a single point of light with no disc,but their brightness provides detail.

Answer 7

It's the atmosphere of the neighboring planets. The same reason why telescopes here on earth can't get those clear images of distant celestial bodies. Too much atmosphere distorting the light.

Answer 8

the whobble telescope dont sound as good as a telescope should be,., those little craters are a telescope lens sitting on the moon, but people think it is where a planet was or ran into,

see if it takes peices of the planet and mails them here that is what a picture is,.

Answer 9

Most of the answers above (at least, the ones in decent syntax) are correct. Do you get it now?

Answer 10

Angular resolution (which is basically what lindajune said.)