Astronomy Roundup: Interstellar Objects, 'Oumuamua, Neptune, and Hot Jupiters

Astronomy Roundup is a regular summary of major events in Astronomy.

A Fireball Over Papua New Guinea
In 2014, a fireball exploded over Papua New Guinea. Papua New Guinea is an island nation in Melanesia, an area in the southwestern Pacific Ocean north of Australia. The U.S. Space Command (USSC) has confirmed that there is something extraordinary about this fireball. It came from another star system. This meteor is the first interstellar object detected in our Solar System.

There are objects like meteors, asteroids, and comets that make their way to the vicinity of Earth from time to time. But all of these objects are believed to have originated in our Solar System. Asteroids come from the Asteroid Belt between Mars and Jupiter. Short-period comets originate in an area of the Solar System called the Kuiper belt, which is beyond Neptune. It extends from the orbit of Neptune at 30 astronomical units (A.U.) to about 50 A.U. from the sun. It is believed that long-period comets originate in the Oort cloud, which extends from outside the Kuiper belt to halfway to the nearest star Proxima Centauri.

So how do astronomers know that this meteor came from outside our Solar System? According to the U.S. Space Command memo, the meteor originated "from an unbound hyperbolic orbit with 99.999% confidence. This event would predate the discovery of 'Oumuamua by about 3 years." It was confirmed that "the velocity estimate reported to NASA is sufficiently accurate to indicate an interstellar trajectory." 

This conclusion comes from a report co-authored by Dr. Abraham (Avi) Loeb. He has a book titled Extraterrestrial: The First Sign of Intelligent Life Beyond Earth. In this book, he argues that 'Oumuamua could possibly be an artificial object built by an alien civilization. Discovered in 2017, 'Oumuamua is a cigar-shaped object that accelerates slightly. Paul Chodas, from NASA's Jet Propulsion Laboratory, said, "It's a strange visitor from a faraway star system, shaped like nothing we've ever seen in our own solar system neighborhood." Avi Loeb argues that this strange visitor could be a lightsail, an alien space probe propelled by the propulsive radiation of starlight. 

An artist’s impression of 'Oumuamua Credit: ESO/M. Kornmesser

Another interstellar object astronomers are aware of is Comet Borisov, discovered by an amateur astronomer in 2019. 

In the News: The Pentagon Just Confirmed the First-Ever Interstellar Visitor to Earth

Temperature Shifts on Neptune
In other news, Neptune experienced an unexplained temperature shift. Just like Earth, Neptune has seasons. However, they are considerably longer than three months. One year on Neptune is 165 Earth years, so a single season lasts around 40 years. It has been summer at Neptune's southern hemisphere since 2005. For reasons astronomers don't understand, the temperature dropped 14 degrees Fahrenheit (8 degrees Celsius) between 2003 and 2018. Then the temperature rose by 20 degrees Fahrenheit (11 degrees Celsius) between 2018 and 2020. Before you start packing for a summer holiday on Neptune, be warned. It is one of the coldest places in the Solar System, with an average temperature of negative 340 degrees Fahrenheit (negative 220 degrees Celsius).

Neptune has unexplained temperature shifts

In the News: Neptune just experienced an unexplained temperature shift

Hot Jupiters
If you have decided to avoid Neptune and are looking for another holiday spot, you might also want to avoid "two strange planets where it rains vapourised rock and the atmosphere is sunburned." The Hubble Space Telescope discovered these two strange 'super-hot Jupiter' planets. Hot Jupiters are a class of gas giant exoplanets physically similar to Jupiter but with very short orbital periods. In other words, unlike our Jupiter, which is far from our sun, Hot Jupiters are very close to their stars. So close that they orbit their sun in a matter of days. For example, 51 Pegasi, called 51 Peg for short, is a Hot Jupiter located in the Constellation Pegasus. It orbits its star every four days.  

WASP-178b is a tidal-locked planet with a cloudless atmosphere. Tidal-locked means one side is always facing its star. This planet has hurricanes of over 2,000 miles per hour on its sunny side, while gas cools to form clouds that rain rocks on its dark side. These rocks vaporize on the planet's surface. WASP-178b has a mass of 1.66 Jupiters. 

Ultraviolet light from its star creates a thermal layer in the atmosphere of sunburned KELT-20b. This planet is 3.382 Jupiters in mass. Both of these planets have orbits of just over three days.

Hot Jupiters Credit: ESA/Hubble

In the News: Hubble Space Telescope reveals two strange planets where it rains vapourised rock and the atmosphere is 'sunburned'

That's it for this Astronomy Roundup. Check back soon for more exciting news in the field of astronomy.

 

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