Why Did Comet Erasmus Wag its Tail Happily as it Passed by the Sun?
In a static image, Erasmus appears indistinguishable from any typical comet. However, as time progressed, its tail revealed a lively wag, reminiscent of an animated and spirited puppy. Credit: NASA.
Renowned astronomer David H. Levy once likened comets to cats, asserting, “They both have tails and do precisely what they want.” With his extensive experience as the co-discoverer of numerous comets, including the infamous Shoemaker-Levy 9, which collided with Jupiter in a spectacular display witnessed globally, Levy’s analogy resonates in the unpredictable nature of these celestial wanderers.
Comet C/2020 S3 (Erasmus): A Cosmic Canine?
Erasmus, with an orbital period spanning 1,800 years, emerged onto the astronomical scene in September 2020. Initially resembling a typical long-period comet, its trajectory hinted at a close encounter with the Sun, venturing as near as Mercury’s orbit.
Despite the challenges posed by its proximity to the Sun, Erasmus exhibited behavior more akin to a dog than a cat, energetically wagging its tail. This anomalous display intrigued astronomers, prompting a closer examination.
Solar Influence: A Wagging Tail Mystery
The STEREO-A and SoHO spacecraft, strategically positioned, provided valuable data for unraveling Erasmus’s peculiarities. Notably, the comet sprouted two tails – one of dust and another of ions – exhibiting an unusual lack of alignment.
As Erasmus approached the Sun, a staggering 12 metric tonnes of water vapor per second erupted from its icy nucleus, accompanied by liberated dust. While conventional wisdom attributes comet tail direction to the solar wind, Professor David Jewitt’s UCLA-led team highlighted the prevailing influence of radiation pressure. This force, ten times more potent than the solar wind, steered the dust tails’ curvature.
Ionized Splendor: The Swishing Plasma Tail
A fraction of Erasmus’s escaping water vapor underwent ionization through exposure to ultraviolet light, forming a discernible plasma tail. Unlike its dusty counterpart, the plasma tail’s orientation was chiefly shaped by the solar wind.
Erasmus’s plasma tail, however, exhibited unprecedented dynamics. Over an 11-day period, it swung dramatically from 150° to 210° relative to the Sun, indicative of solar wind speed variations ranging from 200 to 550 km/s (450,000-1,200,000 Mph). This notable swish could only be explained by a non-radial component of the solar wind.
Solar Wind Swirls: Unveiling the Coronal Mass Ejection Connection
Non-radial solar winds, a phenomenon attributed to various causes, found a probable explanation in a large Coronal Mass Ejection (CME) associated with a sunspot. The CME, oriented away from Earth, remained scarcely known due to its direction.
In the enigmatic tale of Comet Erasmus, the interplay of solar forces and a well-timed CME unraveled a celestial spectacle, challenging conventional expectations of comet behavior. As comets continue to defy predictability, astronomers remain vigilant, ever-ready to witness the next cosmic surprise.
Read the original article on ArXiv.org.
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