Solar System Archives

January 7, 2025January 7, 2025 by Matt Williams

Here's How Pluto and Charon Became a Bizarre Double Planet

Artist's impression of New Horizons' close encounter with the Pluto–Charon system. Credit: NASA/JHU APL/SwRI/Steve Gribben

On July 14th, 2015, the New Horizons probe made history by accomplishing the first flyby of Pluto and its largest satellite, Charon. The stunning images this mission took of these icy worlds have helped scientists address some of the key questions about Pluto and its massive moon, which have been shrouded in mystery for decades (owing to their great distance from Earth). One of the biggest mysteries that scientists have contemplated since Charon was first discovered in 1978 is how it came together with Pluto in the first place.

For decades, astronomers suspected that Pluto and Charon formed through a process similar to Earth and the Moon. This theory, known as the Giant Impact Hypothesis, states that roughly 4.5 billion years ago, primordial Earth was struck by a Mars-sized body named Theia. In a new study, a team of researchers from the University of Arizona challenged this assumption and offered an alternate theory known as “kiss and capture.” Their findings could help scientists better understand how planetary bodies in the outer Solar System form and evolve.

January 2, 2025January 2, 2025 by Brian Koberlein

The Webb Captures Spectra of Trans-Neptunian Objects, and Reveals a History of Our Solar System

Artistic representation of the distribution of trans-Neptunian objects in the planetesimal disk, with overlaid representative spectra of each compositional group highlighting the dominant molecules on their surfaces. Credit: William D. González Sierra/Florida Space Institute, University of Central Florida

Trans-Neptunian Objects (TNOs) are small planetoids that orbit the Sun beyond Neptune and Pluto. Their dark and icy character contains the remnant of the early solar system, and as such, they have the potential to reveal its history. But since they are small, distant, and dim, TNOs are very difficult to study. We know that different groups of TNOs have unique histories based on their surface colors and orbits. A new study has looked at their spectra, and it reveals a rich diversity unseen before now.

December 11, 2024December 11, 2024 by Brian Koberlein

Tidal Steams of Interstellar Objects May Flow Through the Milky Way Like Braided Rivers

How tidal disruption can create a stream of interstellar objects. Credit: NAOC / Y. Zhang

We know that interstellar objects occasionally visit our solar system. So far, we have only discovered two interstellar objects (ISOs), but that’s mainly because we can only distinguish them from solar system bodies by their orbital motion, and that takes a series of observations over time. The two we have discovered, ?Oumuamua and Borisov, were only noticed because they had highly unusual orbits that moved through the inner solar system. But when sky survey telescopes such as the Vera Rubin Observatory come online, we will likely find new interstellar objects all the time. It’s estimated that several ISOs enter the solar system every year, and there could be hundreds of them passing by at any given time. But that raises an interesting question about how these objects arrive. Do they enter our solar system randomly from all directions, or do they appear in clusters a few at a time?

December 10, 2024December 10, 2024 by Mark Thompson

An Interstellar Visitor Helped Shape the Orbits of the Planets.

This artist’s impression illustrates an interstellar object rapidly approaching our Solar System. The object, ejected from its home planetary system long ago, traveled through interstellar space for billions of years before briefly passing through our cosmic neighborhood. Rubin Observatory will reveal many of these previously unknown interstellar visitors. Alt-Text: An artist’s impression of a small, rocky interstellar object hurtling from the upper right toward the inner Solar System. The orbits of the four inner planets (Mercury, Venus, Earth, Mars) are fully visible, drawn as teal concentric circles around the bright ball of the Sun at the center. We see the orbits from a slightly elevated angle, so that the circular paths appear oval. The black background is sprinkled with points of starlight. The interstellar object looks like an elongated potato above the Sun, streaming toward the Sun from the upper right, with a short tail of gas and dust trailing behind.

The orbits of the planets around the Sun have been the source for many a scientific debate. Their current orbital properties are well understood but the planetary orbits have evolved and changed since the formation of the Solar System. Planetary migrations have been the most prominent idea of recent decades suggesting that planetary interactions caused the young planets to migrate inwards or outwards from their original positions. Now a new theory suggests 2-50 Jupiter mass object passing through the Solar System could be the cause.

December 4, 2024December 4, 2024 by Evan Gough

Here’s How Interstellar Objects and Rogue Planets Can be Trapped in the Solar System

Illustration of an interstellar object approaching our solar system. Credit: Rubin Observatory/NOIRLab/NSF/AURA/J. daSilva

When Oumuamua traversed our Solar System in 2017 it was the first confirmed Interstellar Object (ISO) to do so. Then in 2019, Comet 2l/Borisov did the same thing. These are the only two confirmed ISOs to visit our Solar System. Many more ISOs must have visited in our Solar System’s long history, and many more will visit in the future. There are obviously more of these objects out there, and the upcoming Vera Rubin Observatory is expected to discover many more.

It’s possible that the Sun could capture an ISO or a rogue planet in the same way that some of the planets have captured moons.

It all comes down to phase space.

October 2, 2024October 7, 2024 by Nancy Atkinson

NASA Turns Off One of Voyager 2's Science Instruments

Voyager 2. Credit: NASA — Artist's impression of the Voyager 2 space probe. Credit: NASA

The two Voyager spacecraft have been speeding through space since 1977, powered by decaying chunks of plutonium that produce less and less energy every year. With less electricity available, NASA has decided to shut down one experiment on Voyager 2, the plasma science instrument. This device measures the quantity and direction of ionized particles passing the spacecraft. While Voyager 2 still has enough electricity to support its four other operational instruments, it will likely be down to just one by the 2030s.

September 13, 2024September 13, 2024 by Matt Williams

More Bodies Discovered in the Outer Solar System

The Subaru Telescope at the Mauna Kea Observatories, Hawaii. Credit: NAOJ

The outer Solar System has been a treasure trove of discoveries in recent decades. Using ground-based telescopes, astronomers have identified eight large bodies since 2002 – Quouar, Sedna, Orcus, Haumea, Salacia, Eris, Makemake, and Gonggang. These discoveries led to the “Great Planet Debate” and the designation “dwarf planet,” an issue that remains contentious today. On December 21st, 2018, the New Horizons mission made history when it became the first spacecraft to rendezvous with a Kuiper Belt Object (KBO) named Arrokoth – the Powhatan/Algonquin word for “sky.”

Since 2006, the Subaru Telescope at the Mauna Kea Observatory in Hawaii has been observing the outer Solar System to search for other KBOs the New Horizons mission could study someday. In that time, these observations have led to the discovery of 263 KBOs within the traditionally accepted boundaries of the Kuiper Belt. However, in a recent study, an international team of astronomers identified 11 new KBOs beyond the edge of what was thought to be the outer boundary of the Kuiper Belt. This discovery has profound implications for our understanding of the structure and evolution of the Solar System.

September 10, 2024September 10, 2024 by Evan Gough

A Stellar Flyby Jumbled Up the Outer Solar System

This is a screenshot from a supercomputer simulation. It shows how an ancient stellar flyby shaped the Solar System. Among other things, the flyby can explain the Solar System's population of irregular moons. Image Credit: Forschungszentrum Jülich

An ancient passerby may have visited the Sun and inadvertently helped shape the Solar System into what it is today. It happened billions of years ago when a stellar drifter came to within 110 astronomical units (AU) of our Sun. The effects were long-lasting and we can see evidence of the visitor’s fleeting encounter throughout the Solar System.

August 29, 2024August 29, 2024 by Nancy Atkinson

NASA's New Solar Sail Extends Its Booms and Sets Sail

An artist's concept of NASA's Advanced Composite Solar Sail System spacecraft in orbit as the Sun crests Earth's horizon. Credits: NASA/Aero Animation/Ben Schweighart

Solar sails are an exciting way to travel through the Solar System because they get their propulsion from the Sun. NASA has developed several solar sails, and their newest, the Advanced Composite Solar Sail System (or ACS3), launched a few months ago into low-Earth orbit. After testing, NASA reported today that they extended the booms, deploying its 80-square-meter (860 square feet) solar sail. They’ll now use the sail to raise and lower the spacecraft’s orbit, learning more about solar sailing.

“The Sun will continue burning for billions of years, so we have a limitless source of propulsion. Instead of launching massive fuel tanks for future missions, we can launch larger sails that use ‘fuel’ already available,” said Alan Rhodes, the mission’s lead systems engineer at NASA’s Ames Research Center, earlier this year. “We will demonstrate a system that uses this abundant resource to take those next giant steps in exploration and science.”

August 28, 2024August 28, 2024 by Evan Gough

DART Did More Than Deter Dimorphos; It Sent It Into a Chaotic Tumble

Artist's impression of the DART mission approaching the double-asteroid Didymos and its moon Dimorphos. Credit: NASA

In 2022, NASA’s DART (Double Asteroid Redirection Test) spacecraft collided with an object named Dimorphos. The objective was to test redirecting hazardous asteroids by deflecting them with an impact. The test was a success, and Dimorphos was measurably affected.

Follow-up research shows that Dimorphos was more than deflected; it was deformed.