if hubble can take great pictures of other galaxies far away then why cant it take a good pic of pluto??

Answer 1

Pluto is 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 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. Many galaxies and nebulae are considerably closer than that, and therefore appear correspondingly larger. 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 is close but tiny, while galaxies are distant but vast.

Answer 2

Hubble is great at photographing things that generate their own light. Pluto can only reflect sunlight. At its tiny size and low reflectivity, it's extremely dim. And it takes a long time to get enough light to form an image. Between the Earth orbit of the HST and the rotation of Pluto, numerous precisely realigned images have to be taken to get enough light for a recognizable image. Hubble is trying to do something for which it wasn't designed, like using a telescope to read the TV Guide.

Answer 3

Remember that Pluto is very small object out there compared to one of those huge galaxies.Pluto has only a magnitute (brightness) of +14.The naked eye can only see as bright as +6.Galaxies can be many light years away and many light years in diameter.

Answer 4

Planets such as Pluto only reflect the light of the Sun and it's very far away. They have to illumination qualities of their own like a galaxy full of stars which make light like our Sun.

Answer 5

Cuz you aren't Hubble. He was the genius who came up with the theory of the expanding universe.Pluto is much smaller than any galaxy.

Answer 6

Because those galaxies are putting out much, MUCH more light than Pluto is, and they are MUCH bigger. Even though they are far away, they are larger and brighter.

Answer 7

its a matter of focal length at a certain magnification... have you ever tried to take a picture with your digital camera of something only 3 or 4 inches from the camera? notice the camera couldn't focus using the normal settings (you have to switch to macro mode if it has one)? the hubble was designed to focus at very great distances, magnifying a significant amount