Scientists have learned some key characteristics of a gigantic asteroid and its two moons, with a bit of help from sharp-eyed amateur astronomers.
Image 1: Artist’s concept showing the large 270-km asteroid Sylvia surrounded by its two satellites, Romulus and Remus. The primary asteroid of the system may have a dense, regularly-shaped core, surrounded by fluffy material. The two moons are strongly elongated and composed of two lobes. Credit: Danielle Futselaar/SETI Institute
Image 2: Sylvia and its moons as seen from the 8 to 10-meter class telescopes with adaptive optics. The dark circle shows the irregular shape of the asteroid. The small satellites can be seen at various positions on these images. Credit: Franck Marchis
Observations by amateurs helped researchers determine that asteroid (87) Sylvia, a space rock 168 miles wide (270 kilometers), appears to have an irregular shape and a dense, spherical core surrounded by a layer of relatively fluffy material. Further, the asteroid’s larger moon, Romulus, is about 15 miles (24 km) wide, scientists said.
"Combined observations from small and large telescopes provide a unique opportunity to understand the nature of this complex and enigmatic triple asteroid system," study lead author Franck Marchis, of the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, Calif., said in a statement.
"Thanks to the presence of these moons, we can constrain the density and interior of an asteroid, without the need for a spacecraft’s visit," he added. "Knowledge of the internal structure of asteroids is key to understanding how the planets of our solar system formed."
M45 - The Pleiades
Image credit & copyright: Wolfgang Promper
the difference a 2.2 micrometer defect can make. this is M100, as pictured by the Hubble Telescope before and after the problem was solved
The White Wizard (NGC 4921)
science meme | 1 field of science - astronomy
The study of the universe and the objects in it through scientific investigation. Since much of contemporary astronomy uses the laws and methods of physics, the terms “astronomy” and “astrophysics” are usually used interchangeably. However, modern astronomy also uses techniques from many other scientific disciplines, including chemistry, geology, and biology, for which the terms astrochemistry, planetary science, and astrobiology are increasingly used. [x]
Three nebulae: M8, M20 (also known as the Trifid) and NGC 6559, the Lagoon Nebula. Glowing hydrogen gas creates the dominant red color of the emission nebulae, with contrasting blue hues, most striking in the Trifid, due to dust reflecting starlight. (Photo: via Tony Hallas via NASA APOD)
Sunset glow in Orion
Credit: ESA/Hubble & NASA
The magnificent reflection nebula NGC 2023 lies nearly 1500 light-years from Earth. It is located within the constellation of Orion (The Hunter), in a prestigious area of the sky close to the well-known Flame and Horsehead Nebulae. The entire structure of NGC 2023 is vast, at four light-years across. This NASA/ESA Hubble Space Telescope picture just takes in the southern part, with the subtle shades of colour closely resembling those of a sunset on Earth.
NGC 2023 surrounds a massive young B-type star. These stars are large, bright and blue-white in colour, and have a high surface temperature, being several times hotter than the Sun. The energy emitted from NGC2023’s B-type star illuminates the nebula, resulting in its high surface brightness: good news for astronomers who wish to study it. The star itself lies outside the field of view, at the upper left, and its brilliant light is scattered by Hubble’s optical system, creating the bright flare across the left side of the picture, which is not a real feature of the nebula.
Stars are forming from the material comprising NGC 2023. This Hubble image captures the billowing waves of gas, 5000 times denser than the interstellar medium. The unusual greenish clumps are thought to be Herbig–Haro objects. These peculiar features of star-forming regions are created when gas ejected at hundreds of kilometres per second from newly formed stars impacts the surrounding material. These shockwaves cause the gas to glow and result in the strange shapes seen here. Herbig–Haro objects typically only last for a few thousand years, which is the blink of eye in astronomical terms.
This picture was created from multiple images taken with the Wide Field Camera of Hubble’s Advanced Camera for Surveys. Exposures through a blue filter (F475W) are coloured blue, exposures through a yellow filter (F625W) are coloured green and images through a near-infrared filter (F850LP) are shown as red. The total exposure times per filter are 800 s, 800 s and 1200 s, respectively, and the field of view spans 3.2 arcminutes.
Jupiter and Ganymede
Credit: NASA, ESA and E. Karkoschka (University of Arizona)
The NASA/ESA Hubble Space Telescope has caught Jupiter’s moon Ganymede playing a game of “peek-a-boo.” In this crisp Hubble image, Ganymede is shown just before it ducks behind the giant planet.
Ganymede completes an orbit around Jupiter every seven days. Because Ganymede’s orbit is tilted nearly edge-on to Earth, it routinely can be seen passing in front of and disappearing behind its giant host, only to reemerge later.
Composed of rock and ice, Ganymede is the largest moon in our Solar System. It is even larger than the planet Mercury. But Ganymede looks like a dirty snowball next to Jupiter, the largest planet in our Solar System. Jupiter is so big that only part of its Southern Hemisphere can be seen in this image.
Hubble’s view is so sharp that astronomers can see features on Ganymede’s surface, most notably the white impact crater, Tros, and its system of rays, bright streaks of material blasted from the crater.
The image also shows Jupiter’s Great Red Spot, the large eye-shaped feature at upper left. A storm the size of two Earths, the Great Red Spot has been raging for more than 300 years. Hubble’s sharp view of the gas giant planet also reveals the texture of the clouds in the Jovian atmosphere as well as various other storms and vortices.
Astronomers use these images to study Jupiter’s upper atmosphere. As Ganymede passes behind the giant planet, it reflects sunlight, which then passes through Jupiter’s atmosphere. Imprinted on that light is information about the gas giant’s atmosphere, which yields clues about the properties of Jupiter’s high-altitude haze above the cloud tops.
This colour image was made from three images taken on April 9, 2007, with the Wide Field Planetary Camera 2 in red, green, and blue filters. The image shows Jupiter and Ganymede in close to natural colours.
NGC 2787 is a barred lenticular galaxy located some 25 million light years away in the direction of the constellation Ursa Major. Pictured by Hubble, NGC 2787 in the above image spans about 4,500 light years.
Image credit to Marcella Carollo (ETHZ), Hubble Heritage, NASA