Close Encounters with Earth: Comets That Passed Very Closer Than We Thought

Since the ability to accurately determine the paths of comets and other near-Earth objects (NEOs) has improved, we have observed numerous close approaches to Earth. These celestial objects come within a relatively short distance from our planet, causing both wonder and occasional concern. In this article, we explore some of the comets that have had the closest encounters with Earth in recorded history.

The Closest Comet: Lexell's Comet (1770)

In the early 18th century, Lexell's Comet left its mark on history. This comet came within 15,000,000 kilometers of Earth, placing it just 1.5 times the distance from Earth to the Sun or 37 times the distance from Earth to the Moon. This encounter occurred in 1770 and is considered one of the closest passes by a known comet to our planet. At the time, Lexell's Comet was so close that Charles Messier noted the comet's coma appeared to be about four times the apparent size of a full moon.

Second Closest Comet: Comet 55P/1366 U1 Temple-Tuttle

Comet 55P/1366 U1 Temple-Tuttle almost put a second close approach on the list. It is believed to have passed within 8.9 lunar distances from Earth in 1366, which is still considered a very close encounter. However, the exact details of this encounter are less well-documented compared to the Lexell's Comet event.

Comets in Recent Years

Over the past decade, a few comets have passed extremely close to Earth, setting new records for proximity. For instance, in 2016, the comets P/2016 BA14 (Pan-STARRS) and 252P/LINEAR passed within millions of miles of Earth. Another notable event was in 2023, with Comet 41P/Tuttle-Giacobini-Kresak, which approached within 13.2 to 13.7 million miles of Earth.

Notable Events and Concerns

In 1910, when Haley's Comet passed near Earth, there was significant public concern due to the discovery of cyanide gas in its tail. While Earth safely navigated through the comet's tail, this event added to the population's unease about potential comet encounters. In 2023, Comet Swift-Tuttle, known for its retrograde orbit, was briefly thought to pose a collision threat. However, revised calculations confirmed that a collision in 2126 AD is not expected.

Conclusion

Despite the occasional close encounters, no comet is known to have impacted Earth in recent history. Experts in orbital dynamics and NEO tracking systems ensure that any potential threats are identified and assessed. The vast majority of encounters with comets and other NEOs pose no risk to life on Earth, and the experts are committed to providing accurate and reassuring information.

Haley's Comet 1910

The 1910 approach of Haley's Comet was particularly notable. Astronomers discovered cyanide gas in the comet's tail, leading to public panic. The earth actually passed through the tail as the comet approached. Thankfully, the panic was short-lived as we survived the encounter. This event might count as one of the closest passes that caused a significant stir.