Month: April 2023

Around 10 Million Deep Space Visitors Encircle Our Solar System

by Rida Fatima

How many other ‘Oumuamuas’ could there be in and around the solar system?

Figure 1: Rendering of Oumuamua & An artist’s impression of the interstellar comet Borisov ESO/M. Kormesser
(Figure 1: Rendering of Oumuamua & An artist’s impression of the interstellar comet Borisov ESO/M. Kormesser)

Astronomers found an extraterrestrial intruder between 100 and 1,000 metres long in our Solar System in late 2017. A long, narrow slab of rock was named Oumuamua. It was observed as travelling on a track that suggested it was merely passing through our Solar System on its route into the interstellar space. In October 2019, Comet 2I/Borisov flew through our Solar System on a path that showed it had come from somewhere other than our cosy little stellar neighbourhood. The astronomers who observed this comet from a closer perspective labelled Borisov as a “rogue comet”. The presence of these objects tells us that our Solar System is not isolated from the rest of the galaxy.

A Harvard study indicated that there could be around 4 quintillion interstellar objects roaming within our solar system. Almost all of them are visitors from another star present in the Milky Way, and each one was possibly manufactured artificially. The distance between our solar system and its nearest cousin, Proxima Centauri, is significantly greater than the size of our entire solar system. Finding any of the 4 quintillion probable mysterious things for closer examination could be quite difficult.

Harvard astronomer Avi Loeb and his colleagues began with all of the interstellar objects observed by astronomers in the solar system. In other words, these are artefacts that could have originated by an extraterrestrial civilisation just beyond the range of our space probes and telescopes. Apart from Oumuamua, there are few highly potential interstellar visitors that might have arrived from some other star system, the interstellar meteors CNEOS 2014-01-08 and CNEOS 2017-03-09, as well as the interstellar comet Borisov. New telescopes, such as NASA’s James Webb Space Telescope, allow us to peer deeper into the darkness of the deep space and also the outer solar system. It enables the recognition of ever-smaller objects, and to distinguish between local and possible interstellar visitors.

Loeb also mentioned the Vera C. Rubin Observatory, which is now under development in Chile, which is scheduled to open in 2023. This observatory will be capable of observing the entire southern sky every 4 days through its 3.2-billion-pixel camera. “A high-resolution scan may reveal bolts and screws on the surface of a manufactured object and differentiate it from a nitrogen glacier, a hydrogen iceberg, or a dust bunny,” added Loeb.

Figure 2: Twilight photo of Rubin Observatory taken in April 2021. Credit: Rubin Obs./NSF/AURA
(Figure 2: Twilight photo of Rubin Observatory taken in April 2021. Credit: Rubin Obs./NSF/AURA)

Interstellar Objects Should get Pulled Into our Sun’s Gravity

“If you can observe a sizable population of trapped objects, we’ll have a significant amount of data about how many there are in the Milky Way floating around. It will help us to find the composition of the different solar systems from where they are coming from,” says astronomer and statistician Jorge Pearrubia of the University of Edinburg. “And if that’s the case, it’ll be fascinating to learn about the features of those solar systems in the past, as well as their age distribution.” Pearrubia used a horrifying amount of algebra to predict how the gravity of our Sun and Milky Way’s gravity effect interstellar objects that approach our Solar System.

As Oumuamua the interstellar rock approaches the centre of our galaxy, it comes close to a star system with 8 planets and a cluster of smaller debris orbiting a yellowish star, the sun. The Milky Way’s gravity tends to slow the rogue asteroid. The speed of Oumuamua will be reduced enough for the Sun’s gravity to grasp and tug it in for a brief circular dance. Our newly acquired interstellar visitor, however, has not fallen into a stable orbit. Instead, it will only last a few rounds, if that, before the Sun slings it back out into intergalactic space with more energy than before the meeting. In other words, it will wind up in a higher, speedier orbit around the core of the Milky Way.

Detection of Interstellar Visitors

Perhaps the NASA’s JWST cannot reveal the majority of the Oort Cloud because even James Webb’s strong instruments cannot detect the small, frigid things out there in space. However this telescope isn’t our exclusive chance to discover and follow the relatively tiny objects that live on the outskirts of our Solar System. In surveys such as the Sloan Digital Sky Survey and the Catalina Sky Survey, astronomers frequently discover previously unrecognized comets. The ESA’s Gaia Observatory and the Vera Rubin Observatory will also aid in the discovery of new comets, perhaps expanding our present list by several orders of magnitude.

Is this Mini Asteroid our First Interstellar Visitor?

The 3-foot-wide mini-asteroid reached Earth’s atmosphere on January 8, 2014, at a rate of 134,200 mph (216,000 km/h). Furthermore it took an unusual path, implying that it came from beyond the solar system. The authors of the new research concluded the tiny asteroid was, indeed, a newbie into the sun’s part of the Milky Way galaxy by simulating the rock’s route into the past and examining its gravitational impacts with 8 planets in the solar system.

Figure 3: An artist’s conception of a meteor/Image Credit: Shutterstock
(Figure 3: An artist’s conception of a meteor/Image Credit: Shutterstock)

The confirmation makes the rock, dubbed CNEOS 2014-01-08, the first confirmed visitor from interstellar space, hence predating the famed ‘Oumuamua, which flew by Earth in 2017. The second cosmic object comet Borisov, was detected only one year later. Because of the short time span between those findings, astronomers believe that smaller interstellar rocks, only a few feet or tens of feet across, must be far more prevalent in the solar system. They believe even often they cross paths with Earth.

Conclusion

The researchers also speculate that the occurrence of interstellar space rocks throughout Earth’s history may indicate that the origins of life that emerged on our planet in the last 3.5 billion years came from another star system. Astronomers hope to discover that the composition of interstellar objects differs from that of the Solar System. If that is the case, it will open some astonishing doors in unravelling the secrets of the vast and dark universe. It will, for example, assist us in studying the composition and potential indicators of life outside our solar system.

Bibliography

Enceladus Is Blanketed In A Thick Layer Of Snow

by Rida Fatima

This chain of craters on Enceladus looks like a Saturnian snowman
(Fig 1: This chain of craters on Enceladus looks like a Saturnian snowman, but it’s actually made from snow draining into fissures underneath. Picture Credits: JPL-Caltech/NASA, Space Science Institute)

Enceladus, the moon of Saturn, is completely covered in snow. According to recent studies, the downy substance can reach depths of 700 metres in some locations. Few planets in our solar system are more captivating than Saturn’s icy ocean moon Enceladus. Only a few worlds are known to have liquid water seas beneath their icy shells, however Enceladus discharges its ocean into space, where a spacecraft like Cassini can sample it.

According to planetary scientist Emily Martin, who is referencing to the infamously snowy city in New York, “it’s like Buffalo, but worse.” According to a research by Martin and colleagues in the Icarus on March 1, the snow depth raises the possibility that Enceladus’ dramatic plume was more active in the past.

Since the Cassini probe discovered Enceladus’ water- and other-vapor-fueled geysers in 2005, planetary scientists have been fascinated by these discoveries. The salty ocean beneath the frozen shell is most likely where the spray comes from (Grossman, 2023). One of Saturn’s rings is formed by some of that water. The majority of it, according to Martin, returns to the lunar surface as snow. Understanding the features of that snow, such as its thickness and density and compactness, may serve to enlighten Enceladus’ past and pave the path for future missions to this moon.

“If you’re going to drop a robot there,” says Martin of the National Air and Space Museum in Washington, D.C., “you need to realize what it’s going to crash into.” Martin and colleagues compared Earth’s snow cover to that of Iceland to establish the thickness of Enceladus’ snow. Furthermore, pit chains, which are lines of pockmarks in the earth caused by loose debris such as rocks, ice, or snow flowing into a crack beneath, are a geological phenomenon visible throughout the island nation (Grossman, 2023).

Measuring The Depth Of The Snow

All around the solar system, including Enceladus, similar features can be observed. Previous research provided a method for measuring the depth of the pits using geometry and the angle at which sunlight strikes the surface. The depth of the substance the pits are buried in can then be determined by that measurement. Martin and her coworkers were sure that the same method would be effective on Enceladus after a few weeks of fieldwork in Iceland in 2017 and 2018. Martin and other researchers discovered that the snow’s thickness varies across Enceladus’ surface using pictures from Cassini. Most of the time, it is hundreds of meters deep, and at its thickest, it is 700 meters deep (Grossman, 2023).

Enceladus Sprays Dramatic Plumes Of Water Vapor

Rows of plumes rise from ice fractures on the surface of Enceladus.
(Fig 2: Rows of plumes rise from ice fractures on the surface of Enceladus. Picture Credit: NASA/JPL-Caltech, via Space Science Institute)

Martin, on the other hand, says it’s impossible to understand how all that snow got there. If the plume’s spray was constant, it would take 4.5 billion years, or the entire history of the solar system, to collect that much snow on the surface. Even so, the snow would have to be extraordinarily fluffy. Martin believes it is unlikely that the plume triggered and remained consistent at the same time as the moon developed. Even if it did, further snowfall would have compressed the previous layers, resulting in a much thinner stratum than it is now. (Chang, 2017).

Martin stated in a research discussion, “It makes me think we don’t have 4.5 billion years to do this.” The plume may have been considerably more active in the past. “We must do it in a lot less time. The plume has to be turned up loud and clear. Shannon MacKenzie is a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel in Maryland, according to Shannon, the idea is amazing. Without rovers or astronauts on the ground, it is difficult to sweep away snow and measure its depth. Instead, the writers are expertly leveraging geology as their rovers and shovels.

MacKenzie oversaw a mission concept study for an orbiter and lander that might someday travel to Enceladus, but she was not involved in the new work (Grossman, 2023). The study’s main concern was where a lander could land without risk. What do we anticipate the surface to be, she says, was crucial to those conversations? “Identify the places that are too fluffy to land in,” according to the new paper.

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