16 Psyche facts for kids
16 Psyche imaged by the Very Large Telescope's adaptive optics system in August 2019
|
|
| Discovery | |
|---|---|
| Discovered by | Annibale de Gasparis |
| Discovery site | Naples Obs. |
| Discovery date | 17 March 1852 |
| Designations | |
| MPC designation | (16) Psyche |
|
Named after
|
Psyche (Ψυχή) |
| Main belt | |
| Adjectives | Psychean |
| Orbital characteristics | |
| Epoch 13 September 2023 (JD 2453300.5) |
|
| Aphelion | 3.32 AU (497 million km) |
| Perihelion | 2.53 AU (378 million km) |
| 2.92 AU (437 million km) | |
| Eccentricity | 0.1342 |
| 4.999 yr (1825.95 d) | |
| 243.16° | |
| Inclination | 3.096° |
| 150.03° | |
| 27 April 2025 | |
| 229.41° | |
| Earth MOID | 1.53 AU (229 million km) |
| Physical characteristics | |
| Dimensions | c/a = 0.59±0.02 (278±5 × 232±6 × 164±4) km [best ellipsoid fit = 277 km × 238 km × 168 km] 279 × 232 × 189 km ( ± 10% ) (278+4 −8 × 238+4 −6 × 171+1 −5) km |
|
Mean diameter
|
223±3 km 222±4 km 222+1 −4 km |
| Volume | 5.75×106 km3 (best fit) |
| Mass | (2.29±0.14)×1019 kg |
|
Mean density
|
3.977±0.253 g/cm3 |
| ~0.144 m/s2 | |
| ~180 m/s (~600 ft/s) | |
| 4.195948±0.000001 h | |
| Albedo | 0.15±0.03 0.34±0.08 (radar) |
|
Spectral type
|
Tholen = M SMASS = X Bus-DeMeo = Xk |
| 9.22 to 12.19 | |
| 6.21 | |
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16 Psyche is a huge asteroid discovered by an Italian astronomer named Annibale de Gasparis on March 17, 1852. It's named after the Greek goddess Psyche. The "16" in its name means it was the 16th small planet (or asteroid) ever found.
It's the biggest and heaviest of its kind, called an M-type asteroid. It's also one of the top 12 most massive asteroids known! Psyche is about 220 kilometers (137 miles) wide. It holds about one percent of all the stuff in the asteroid belt. For a long time, scientists thought it might be the leftover core of a baby planet. However, new studies suggest that's probably not true.
A special spacecraft, also named Psyche, was launched on October 13, 2023. It's heading to the asteroid Psyche and should arrive in 2029. This will be the first time a spacecraft visits an asteroid made mostly of metal!
Contents
Understanding the Symbol for Asteroid Psyche
Long ago, astronomers made special symbols for the first 15 asteroids they found. These symbols were like a quick way to write down the asteroid's name, similar to how older symbols were used for planets. Psyche was given its own special symbol too.
The symbol for Psyche was a butterfly's wing with a star on top (.svg){kind=small}
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). This is because the butterfly was a Greek symbol for the soul. The word psyche in Greek means both "butterfly" and "soul."
However, these unique symbols for asteroids didn't last long. As more and more asteroids were discovered, it became too hard to remember all their different symbols. In 1851, a German astronomer named Johann Franz Encke suggested using a circled number instead. So, 16 Psyche was the first asteroid to use this new number system: ⑯.
What Makes Psyche Special?
How Big Is Asteroid Psyche?
Scientists first guessed Psyche's size using infrared light from the IRAS telescope. They thought it was about 253 kilometers (157 miles) wide. This was a bit bigger than what we know now. But it was a good guess because of how Psyche was facing the telescope at that time.
Psyche has passed in front of a star nine times, blocking its light. This is called an occultation. Four of these events (in 2004, 2010, 2014, and 2019) gave scientists a lot of information. By combining this data with special imaging and 3D models, they now agree that Psyche is about 222 kilometers (138 miles) wide.
How Heavy Is Psyche and What Is It Made Of?
Psyche is so massive that its gravity actually pulls on other asteroids. By studying how it affects their paths, scientists can figure out Psyche's mass. Early guesses for Psyche's mass varied a lot. But now, most estimates are close to 2.287 followed by 19 zeros kilograms.
If we combine its mass with its size, we can find its density. Psyche's density is about 3.977 grams per cubic centimeter. This is much higher than most small objects in our Solar System. This high density suggests that Psyche has a lot of metal inside.
Psyche's Shape and How It Spins
Scientists have created 3D models of Psyche's shape. They used information from how its brightness changes as it spins, special telescope images, and radar observations. The newest models show that Psyche is shaped like a Jacobi ellipsoid. This is like a squashed sphere, similar to a potato. Its dimensions are roughly 278 km by 238 km by 171 km.
These models also help us understand how Psyche spins. It rotates around a pole that is tilted about 98 degrees towards the ecliptic. This means it's almost spinning on its side!
What Features Are on Psyche's Surface?
Scientists have found several interesting features on Psyche. The biggest ones are areas where there seems to be less mass than expected. These areas are similar to a huge basin found on another asteroid called 4 Vesta.
There are also several craters that scientists have seen. Using the Very Large Telescope, observers reported two large craters, about 90 km (56 miles) wide. They were temporarily named Meroe and Panthia. The Arecibo Radar Telescope also found craters near the south pole (Delta), southern middle areas (Eros), and the north pole (Foxtrot). Scientists are pretty sure that Panthia and Eros are real craters, and Foxtrot is likely real too. But they are still checking on Meroe and Delta.
Early studies showed that Psyche's surface brightness changes a lot. Newer models that map the surface brightness show areas that are more than 20% darker or brighter than the average. Interestingly, the Meroe crater is in a very dark area, while the Panthia crater is in a very bright area.
Radar observations from the Arecibo Telescope show that Psyche's surface reflects radar signals well. This is similar to other M-type asteroids. This suggests that its surface is made of rocky material called silicates, mixed with a lot of metal. In some spots, Psyche reflects radar signals almost twice as much! This means these areas have even higher amounts of metal. One of these super-bright radar spots matches the optically bright Panthia crater. This suggests that areas with lots of metal might also be brighter to our eyes.
What Is Psyche Made Of?
Psyche's high density (about 3.9 grams per cubic centimeter) tells us a lot about what it's made of. Pure iron-nickel metal, like what's found in most iron meteorites, is much denser (about 7.9 grams per cubic centimeter). If Psyche were a pure metal core, it would have to be about 50% empty space, which is very unlikely for an object its size.
However, there are other types of metal-rich meteorites that have similar densities to Psyche. These include enstatite chondrites, bencubbinites, and mesosiderites. These are mixtures of metal and rock.
Scientists have also found signs of silicate minerals (rocky materials) on Psyche's surface. In 2016, observations showed evidence of hydroxyl ions. These might mean there are hydrated silicates (rocks with water in their structure) on the asteroid. Since Psyche likely formed in dry conditions, this water might have come from smaller, carbon-rich asteroids hitting it in the past.
Psyche's radar reflectivity changes a lot across its surface. This suggests that the density of the material on its surface (called regolith) varies from 2.6 to 4.7 grams per cubic centimeter. This range fits with the metal-rich meteorites mentioned earlier and the discovery of silicate minerals. It does not fit with a surface made only of iron-nickel unless it's full of holes.
How Did Psyche Form?
Scientists have a few ideas about how Psyche came to be.
- Idea 1: A Leftover Core? The earliest idea was that Psyche is the exposed metallic core of a much larger "baby planet" (a planetesimal) that was hit by something huge. This collision would have stripped away its outer layers of rock. Some thought it was not one big hit, but many smaller, slow collisions. However, this idea is less popular now because Psyche's mass and density don't quite match what we'd expect from a pure core.
- Idea 2: Re-formed After a Smash-Up? Another idea is that Psyche was once broken apart by a huge impact. Then, its pieces (a mix of metal and rock) came back together due to gravity. If this is true, Psyche could be the parent body of mesosiderites, which are meteorites made of both stone and iron.
- Idea 3: Metal Volcanoes? A third idea is that Psyche is a differentiated object, meaning it has layers like Earth (like 1 Ceres and 4 Vesta). But, while it was still cooling, it might have had a type of "iron volcanism," where molten metal erupted onto its surface. If this is true, then areas with metal volcanoes would have a lot of metal. Recent radar observations seem to support this idea.
Exploring Asteroid Psyche
No spacecraft has ever visited Psyche before. But in 2014, a team of scientists proposed a mission to NASA. This team, led by Lindy Elkins-Tanton from Arizona State University, suggested sending a robotic orbiter called Psyche. They argued that 16 Psyche would be a very important object to study because it's the only asteroid found so far that seems to be mostly metal, like a planetary core.
The spacecraft would orbit Psyche for 20 months. It would study the asteroid's surface, gravity, magnetism, and other features. The mission was designed to use existing technology to keep costs down. In 2015, the Psyche mission was chosen as one of five top proposals for NASA's Discovery Program.
NASA officially approved the mission on January 4, 2017. It was first planned to launch in October 2023, reach Mars in 2025, and arrive at Psyche in 2030. But in May 2017, the launch date was moved up to 2022 to use a more efficient path. This would allow it to arrive in 2026.
On February 28, 2020, NASA gave SpaceX a contract to launch the Psyche spacecraft. It would launch on a Falcon Heavy rocket, along with two smaller missions. The spacecraft successfully launched on October 13, 2023, and is expected to reach Psyche in 2029.
Asteroid Psyche will next come closest to Earth on August 6, 2024. At that time, it will be about 1.7 AU (about 254 million kilometers or 158 million miles) away.
See also
- List of minor planets and comets visited by spacecraft
- List of missions to minor planets
- Asteroid mining
- Colonization of the asteroid belt
- Gravity elevator
In Spanish: (16) Psyche para niños
