Photograph of the full disc of the asteroid 162173 Ryugu, as it appeared to the Hayabusa2 spacecraft at 03:50 UTC on 26 June 2018. source
Photograph of the full disc of the asteroid 162173 Ryugu, as it appeared to the Hayabusa2 spacecraft at 03:50 UTC on 26 June 2018. source
And that’s when Earth made dolphins. LOL.
The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt is also termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid belt is approximately 4% that of the Moon, or 22% that of Pluto, and roughly twice that of Pluto’s moon Charon (whose diameter is 1200 km).
The asteroid belt formed from the primordial solar nebula as a group of planetesimals. Planetesimals are the smaller precursors of the protoplanets. Between Mars and Jupiter, however, gravitational perturbations from Jupiter imbued the protoplanets with too much orbital energy for them to accrete into a planet.
source | images: NASA,
SOFIA/Lynette Cook, ESO/M. Kornmesser
Ceres is the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter, slightly closer to Mars’ orbit. Its diameter is approximately 945 kilometers (587 miles), making it the largest of the minor planets within the orbit of Neptune. The 33rd-largest known body in the Solar System, it is the only dwarf planet within the orbit of Neptune. Composed of rock and ice, Ceres is estimated to compose approximately one third of the mass of the entire asteroid belt. Ceres is the only object in the asteroid belt known to be rounded by its own gravity (though detailed analysis was required to exclude 4 Vesta). From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, peaking once every 15 to 16 months, hence even at its brightest it is too dim to be seen with the naked eye except under extremely dark skies.
Dawn revealed that Ceres has a heavily cratered surface; nevertheless, Ceres does not have as many large craters as expected, likely due to past geological processes. An unexpectedly large number of Cererian craters have central pits, perhaps due to cryovolcanic processes, and many have central peaks. Ceres has one prominent mountain, Ahuna Mons; this peak appears to be a cryovolcano and has few craters, suggesting a maximum age of no more than a few hundred million years. A later computer simulation has suggested that there were originally other cryovolcanoes on Ceres that are now unrecognisable due to viscous relaxation. Several bright spots have been observed by Dawn, the brightest spot (“Spot 5”) located in the middle of an 80-kilometer (50 mi) crater called Occator. From images taken of Ceres on 4 May 2015, the secondary bright spot was revealed to actually be a group of scattered bright areas, possibly as many as ten. These bright features have an albedo of approximately 40% that are caused by a substance on the surface, possibly ice or salts, (with the realization of new studies are now likely deposits of salt composed mainly of hydrated magnesium sulphate). reflecting sunlight.
Daniel Machacek (false color images)
So this interstellar asteroid keeps getting weirder and weirder. Everything we know says it should be a comet, but it doesn’t appear to be. Or maybe it is?? You can read more about it here:
As of November 2014, these are all of the planetary, lunar and small body surfaces where humanity has either lived, visited, or sent probes to.
Here is a list of some curiosities of astronomy and astrophysics. From our solar system to interstellar space.
Mercury is shrinking: It’s small, it’s hot and it’s shrinking. A NASA-funded research suggests that Mercury is still contracting today, joining Earth as a tectonically active planet.
Proxima Centauri is a red dwarf, a small low-mass star, about 4.25 light-years (1.30 pc) from the Sun in the constellation of Centaurus. Proxima Centauri is the nearest star of the Sun that is known and at first can only be seen from the Southern Hemisphere.
A heavy star:
5 milliliters, or one teaspoon of neutron star material, equals the weight of about 900 Great Pyramids of Giza. One sugar cube equates to 100 billion tons. A cubic meter? The entire weight of the Atlantic Ocean. With an escape velocity of 100,000 km/s (Earth’s is a puny 11.3 km/s), a fall from 1 meter above a neutron star would only take one microsecond, and you would impact at around 2000 km/s, or 7.2 million kilometers per hour. This force would destroy all your component atoms, rendering all your matter identical. Fortunately, the closest neutron star is rather far away (about 400 light-years), so I wouldn’t be too concerned about the aforementioned event.
The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets.
About half the mass of the belt is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid belt is approximately 4% that of the Moon, or 22% that of Pluto, and roughly twice that of Pluto’s moon Charon (whose diameter is 1200 km).
Sunlight Takes Around 8 Minutes To Reach Earth: The Earth is located 93 million miles (150 million kms) away from the Sun, a distance known to astronomers as an astronomical units or AU. Traveling at the speed of light (186,282 miles per second), sunlight is able to cross this vast distance in around 8 minutes 20 seconds.
Pluto is about 2,376 km in diameter. Pluto’s small size and low mass mean that it has a density of 1.86 grams per cubic centimeter according to recent measurements by New Horizons, about 40 percent of Earth’s density.
Just like black holes; neutron stars also generate gravitational waves: This year astronomers were able to detect gravitational waves originating from neutron stars. And in addition, it was possible to observe the location of the collision thanks to the efforts of the astronomers. This is a great advance for astronomy.
Most neutron stars are very fast rotators: Since the conservation of angular momentum following a supernova explosion transfers the progenitor star’s rate of rotation to the remnant that is only about 20 km (12.5 miles) in diameter, the result is that the neutron star rotates very rapidly when it is formed. Most known neutron stars rotate several hundred times per second, but the fastest rotator yet discovered, the neutron star designated PSR J1748-2446ad, is known to rotate 716 times per second, which translates into 43,000 rotations per minute, or 24% of the speed of light at the star’s equatorial surface.
Asteroid also has satellite:
This color picture is made from images taken by the imaging system on the Galileo spacecraft about 14 minutes before its closest approach to asteroid 243 Ida on August 28, 1993. Ida’s moon, Dactyl, was discovered by mission member Ann Harch in images returned from Galileo. It was named after the Dactyls, creatures which inhabited Mount Ida in Greek mythology. Ida has an average diameter of 31.4 km (19.5 mi). It is irregularly shaped and elongated, and apparently composed of two large objects connected together. Its surface is one of the most heavily cratered in the Solar System, featuring a wide variety of crater sizes and ages.
Kepler-444 system: The oldest known planetary system has five terrestrial-sized planets, all in orbital resonance. This weird group showed that solar systems have formed and lived in our galaxy for nearly its entire existence. Estimated to be 11.2 billion years old (more than 80% of the age of the universe), approximately 117 light-years (36 pc) away from Earth in the constellation Lyra.
Solar System’s First Interstellar Visitor Dazzles Scientists
Astronomers recently scrambled to observe an intriguing asteroid that zipped through the solar system on a steep trajectory from interstellar space—the first confirmed object from another star.
Now, new data reveal the interstellar interloper to be a rocky, cigar-shaped object with a somewhat reddish hue. The asteroid, named ‘Oumuamua by its discoverers, is up to one-quarter mile (400 meters) long and highly-elongated—perhaps 10 times as long as it is wide. That aspect ratio is greater than that of any asteroid or comet observed in our solar system to date. While its elongated shape is quite surprising, and unlike asteroids seen in our solar system, it may provide new clues into how other solar systems formed.
The observations and analyses were funded in part by NASA and appear in the Nov. 20 issue of the journal Nature. They suggest this unusual object had been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with our star system.
“For decades we’ve theorized that such interstellar objects are out there, and now – for the first time – we have direct evidence they exist,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington. “This history-making discovery is opening a new window to study formation of solar systems beyond our own.”
Immediately after its discovery, telescopes around the world, including ESO’s Very Large Telescope in Chile and other observatories around the world were called into action to measure the object’s orbit, brightness and color. Urgency for viewing from ground-based telescopes was vital to get the best data.
This very deep combined image shows the interstellar asteroid ‘Oumuamua at the centre of the picture.
Combining the images from the FORS instrument on the ESO telescope using four different filters with those of other large telescopes, a team of astronomers led by Karen Meech of the Institute for Astronomy in Hawaii found that ‘Oumuamua varies in brightness by a factor of ten as it spins on its axis every 7.3 hours. No known asteroid or comet from our solar system varies so widely in brightness, with such a large ratio between length and width. The most elongated objects we have seen to date are no more than three times longer than they are wide.
“This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape,” said Meech. We also found that it had a reddish color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it.”
These properties suggest that ‘Oumuamua is dense, comprised of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years.
A few large ground-based telescopes continue to track the asteroid, though it’s rapidly fading as it recedes from our planet. Two of NASA’s space telescopes (Hubble and Spitzer) are tracking the object the week of Nov. 20. As of Nov. 20, ‘Oumuamua is travelling about 85,700 miles per hour (38.3 kilometers per second) relative to the Sun. Its location is approximately 124 million miles (200 million kilometers) from Earth – the distance between Mars and Jupiter – though its outbound path is about 20 degrees above the plane of planets that orbit the Sun. The object passed Mars’s orbit around Nov. 1 and will pass Jupiter’s orbit in May of 2018. It will travel beyond Saturn’s orbit in January 2019; as it leaves our solar system, ‘Oumuamua will head for the constellation Pegasus.
Observations from large ground-based telescopes will continue until the object becomes too faint to be detected, sometime after mid-December. NASA’s Center for Near-Earth Object Studies (CNEOS) continues to take all available tracking measurements to refine the trajectory of 1I/2017 U1 as it exits our solar system.
This remarkable object was discovered Oct. 19 by the University of Hawaii’s Pan-STARRS1 telescope, funded by NASA’s Near-Earth Object Observations(NEOO) Program, which finds and tracks asteroids and comets in Earth’s neighborhood. NASA Planetary Defense Officer Lindley Johnson said, “We are fortunate that our sky survey telescope was looking in the right place at the right time to capture this historic moment. This serendipitous discovery is bonus science enabled by NASA’s efforts to find, track and characterize near-Earth objects that could potentially pose a threat to our planet.”
Preliminary orbital calculations suggest that the object came from the approximate direction of the bright star Vega, in the northern constellation of Lyra. However, it took so long for the interstellar object to make the journey – even at the speed of about 59,000 miles per hour (26.4 kilometers per second) – that Vega was not near that position when the asteroid was there about 300,000 years ago.
While originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it slingshotted past the Sun on Sept. 9 at a blistering speed of 196,000 miles per hour (87.3 kilometers per second).
The object has since been reclassified as interstellar asteroid 1I/2017 U1 by the International Astronomical Union (IAU), which is responsible for granting official names to bodies in the solar system and beyond. In addition to the technical name, the Pan-STARRS team dubbed it ‘Oumuamua (pronounced oh MOO-uh MOO-uh), which is Hawaiian for “a messenger from afar arriving first.”
Astronomers estimate that an interstellar asteroid similar to ‘Oumuamua passes through the inner solar system about once per year, but they are faint and hard to spot and have been missed until now. It is only recently that survey telescopes, such as Pan-STARRS, are powerful enough to have a chance to discover them.
“What a fascinating discovery this is!” said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory, Pasadena, California. “It’s a strange visitor from a faraway star system, shaped like nothing we’ve ever seen in our own solar system neighborhood.”
NASA’S First Asteroid Deflection Mission Enters Next Design Phase
The first-ever mission to demonstrate an asteroid deflection technique for planetary defense – the Double Asteroid Redirection Test (DART) – is moving from concept development to preliminary design phase, following NASA’s approval on June 23.
“DART would be NASA’s first mission to demonstrate what’s known as the kinetic impactor technique – striking the asteroid to shift its orbit – to defend against a potential future asteroid impact,” said Lindley Johnson, planetary defense officer at NASA Headquarters in Washington. “This approval step advances the project toward an historic test with a non-threatening small asteroid.”
The target for DART is an asteroid that will have a distant approach to Earth in October 2022, and then again in 2024. The asteroid is called Didymos – Greek for “twin” – because it’s an asteroid binary system that consists of two bodies: Didymos A, about one-half mile (780 meters) in size, and a smaller asteroid orbiting it called Didymos B, about 530 feet (160 meters) in size. DART would impact only the smaller of the two bodies, Didymos B.
Read more at: NASA
243 Ida and its moon photographed by the Galileo spacecraft