This interstellar asteroid accelerates

by Steven Spence

@TheStevenSpence

First asteroid of the genre

In October 2017, Oumuamua – or 1I / 2017 U1 – became the first interstellar asteroid detected by humans, it also changed the way comets and asteroids are named The technical names of comets begin with the letter C, while the asteroids carry the letter A. Following the discovery of Oumuamua, the International Astronomical Union introduced the letter I to designate interstellar objects.

What do we know about Oumuamua?

Oumuamua, which means " a messenger from afar " in Hawaiian, was discovered on October 19, 2017 by the Pan-STARRS1 telescope of the University of Hawaii . The telescope is part of a NASA-funded program to discover and track asteroids and comets near the Earth's orbit. Initially, scientists were not sure of the object. It was first classified as a comet while details on its orbit and composition were still being developed. Later, scientists decided to reclassify it as an asteroid because of the lack of visible activity of the comet. Scientists also have not been able to measure a cyanide gas emission, typically observed in the degassing of comets formed in our solar system.

Oumuamua has a complex rotary motion. It turns on its axis about every seven hours and 20 minutes. The asteroid is also of unusual shape. Depending on the observed luminosity variations and the rotation of the asteroid, the models indicate that the asteroid is about five times longer (~ 800 meters) than its diameter (~ 160 meters).

Oumuamua has a dull red color. Scientists believe that its surface has been reddened by cosmic rays as it travels through interstellar space. The object is dense and rocky or metallic, with little dust or ice detected. No coma of dust and gas from Oumuamua is visible in telescopes, as would be the case with a typical comet.

Interstellar origin of the asteroid

Oumuamua moves on an open hyperbolic trajectory with an eccentricity of 1,2 3 across our solar system, which is why astronomers have quickly could identify it as an interstellar object. The orbital trajectory calculations indicate that the asteroid has come from the direction of Vega in the constellation Lyra. He comes out of the solar system on a trajectory that will take him into the big square of the constellation Pegasus.

Oumuamua moves too fast (~ 26 km / s) for the sun to capture. At perihelion, its nearest approach to the sun, Oumuamua was traveling at 87.7 km / s. The asteroid was moving so fast that it could have traveled the average distance between the Earth and the Moon in just 73 minutes! For comparison, Apollo flights to the moon took about three days to move from Earth's orbit to lunar orbit. New Horizons, the spacecraft sent to Pluto, covered the distance in eight hours. In comparison, if we could drive the moon at a typical speed of 130 km / h, it would take about 123 days of non-stop driving to get there.

Oumuamua Accelerated

As detailed in an article recently published in Nature the team led by the author of the European Space Agency, Marco Micheli proved that the asteroid is not moving as expected. In fact, it has passed Jupiter's orbit earlier than expected, indicating that it has accelerated along its trajectory. Oumuamua was about 100,000 km away that could be explained on the basis of purely gravitational interactions. This sounds like a huge distance, but at the speed of the asteroid, this difference amounts to overtaking Jupiter about 64 minutes earlier. For the scale, at its average distance from the sun, Jupiter is about 774 million km (~ 43 minutes of light) from the sun. A gap of 100,000 km represents only 0.01%, which does not seem huge but is measurable. In space, small percentages can quickly become a large number in absolute terms.

Astronomers spent weeks analyzing the gap between Oumuamua's observed trajectory data and the predicted position. In their article published in Nature on June 27, 2018, Marco Micheli and his colleagues reported how they identified the reason for the acceleration of Oumuamua. After ruling out the effects of 'solar radiation pressure, frictional and frictional forces, interaction with the solar wind for a highly magnetized object and geometric effects', they concluded that the Oumuamua was accelerating because of the "comet". This means that Oumuamua vents gas when it is heated in the same way as a comet.

Asteroid leaving the solar system

Oumuamua passed the orbit of Jupiter in early May 2018. It will cross the orbit of Saturn in January 2019, Uranus in August 2020 and Neptune in June 2024. By the end of 2025, Oumuamua will reach the outer edge of the Kuiper belt, then the heliopause. border – the edge of the solar system – in November 2038.

– Steven brings photography and general science articles to GotScience. He keeps his little garden harmless with ladybugs, lavender and sometimes soap. Steven is interested in astronomy, dinosaurs, birds of prey, and everything related to Calvin and Hobbes