Can Hubble take pictures of Earth?
The surface of the Earth is whizzing by as Hubble orbits, and the pointing system, designed to track the distant stars, cannot track an object on the Earth. The shortest exposure time on any of the Hubble instruments is 0.1 seconds, and in this time Hubble moves about 700 meters, or almost half a mile. So a picture Hubble took of Earth would be all streaks.
A New Zealand man has become the first amateur astronomer to take a direct photograph of a solar system in the first stages of development. Rolf Olsen's stunning image shows Beta Pictoris, a bright young star in the southern hemisphere, surrounded by a "circumstellar disk" - a huge, flat cloud of swirling debris kicked up by a flurry of comet, asteroid and minor body collisions near the new star.
Photographing circumstellar disks is difficult, however, because light from the central star normally swamps the faint glow of the material around it. Powerful telescopes and new data filtering techniques have allowed astronomers to subtract the flood of distant starlight, revealing light from the objects near it, but most amateurs don't attempt such procedures. Olsen achieved the feat by carefully following steps outlined in an academic article about Beta Pictoris, he said.
That paper, written by Lecavelier and his colleagues, described a method of imaging the Beta Pictoris system by taking a photo of a similar reference star under the same conditions, and then subtracting an equal amount of light, pixel for pixel, from his Beta Pictoris image. "For this purpose, I used Alpha Pictoris," Olsen said. "This star is of nearly the same spectral type ... and is also close enough to Beta in the sky so that the slight change in telescope orientation should not affect the diffraction pattern." (Diffraction caused the crosshairs seen in the photo.)
Olsen adjusted the exposure time of his photos of the stars to equalize their brightness. He then used simple software to subtract the image of Alpha from his image of Beta, producing a magnificent picture of the Beta Pictoris solar system with a shadowy spot in place of its central star, and the circumstellar disk radiating out from it.
"I was very excited when I saw that I had a faint signal from the disk itself. I lined up my image and checked it against the professional images, and I was happy to see that the orientation of what looked like the dust disk in my image coincided perfectly with what I could see in the professional images. It feels great to have captured this image," Olsen wrote in an email.
A gigantic object the size of a planet has appeared on astronomers' screens lurking near Mercury, with UFO hunters around the world wondering whether it’s an alien ship.
The object appears from nowhere in a sequence of images of a coronal ejection from the Sun, taken by a Nasa telescope.
As the flare races past Mercury, a huge round object appears next to it—but Nasa scientists insist that the object is merely a result of the way the images are processed.
Users browsing this forum: No registered users and 1 guest