Interstellar Object 3I/ATLAS Approaches the Solar System

Interstellar Object Confirmed

Astronomers have confirmed that an object recently observed in the outer solar system originated from interstellar space.

Yesterday, the object was named A11pl3Z. It has now been designated 3I/ATLAS, where the "I" stands for "interstellar."

Current Location and Movement

3I/ATLAS is currently positioned between the orbits of the asteroid belt and Jupiter, approximately 416 million miles from the Sun, according to NASA. This distance is about four and a half times that between Earth and the Sun.

The object is moving toward the inner solar system at a speed of about 130,000 miles per hour.

Paul Chodas, director of the Center for Near Earth Object Studies at NASA's Jet Propulsion Laboratory, stated that tracing the object's orbit backward suggests it is coming from the general direction of the center of the galaxy. He added that it definitely originated from another solar system, though the specific source is unknown.

Previous Interstellar Objects

3I/ATLAS is the third confirmed interstellar object to enter the solar system. The first was 'Oumuamua, observed in 2017, which was noted for its elongated shape. The second, Borisov, was a comet that began to break apart after its discovery.

The current object also appears to be a comet, making it the second known interstellar comet.

Discovery and Confirmation

The discovery and confirmation of 3I/ATLAS involved collaboration among multiple observatories. Initially identified as a possible asteroid by a telescope in Chile that is part of the Asteroid Terrestrial-impact Last Alert System (ATLAS), the object was quickly added to the International Astronomical Union's Minor Planet Center list of confirmed near-Earth objects. NASA and its Jet Propulsion Laboratory also included it in their records.

Over 100 observations from telescopes worldwide were reported, including indications of cometary activity, according to the Minor Planet Center. This data led to its designation as 3I/ATLAS.

Chodas stated that there is no uncertainty about its interstellar origin due to its high velocity, which is inconsistent with objects originating from the solar system.

Origin and Size Estimates

The object's origin is not definitively known. It is likely that it formed as a comet around another star and was ejected from its original system by a gravitational interaction, possibly with a passing star.

There is ongoing discussion regarding the size of 3I/ATLAS. If it were a rocky asteroid, it would need to be about 12 miles wide to reflect the observed light levels. However, as a comet, determining its size is more complex. Comets have a luminous coma of gas and dust that can make them appear much larger than the solid core. For example, Borisov's coma was estimated to be nearly 100,000 miles long.

Chodas noted that the size of the solid object cannot be inferred from the brightness of the coma, so it is too early to determine the object's dimensions.

Observation Opportunities

There will be significant opportunities to study 3I/ATLAS, unlike previous interstellar objects such as 'Oumuamua, which was observable for only a few weeks.

Chodas indicated that 3I/ATLAS should remain visible to large telescopes around the world well into next year.

3I/ATLAS is expected to reach its closest approach to the Sun around October 30, at a distance of about 130 million miles, placing it inside the orbit of Mars.