Source: TOI
Context: Two rare celestial visitors — Comet C/2025 R2 (SWAN) and Comet C/2025 A6 (Lemmon) — have been captured over Indian skies this week, marking a rare dual appearance of bright comets.
About Comets in the News:
- Comet C/2025 R2 (SWAN):
- Detected by the Solar and Heliospheric Observatory’s SWAN instrument.
- Has a faint but visible tail; will not return for nearly 20,000 years.
- Currently visible above the Sagittarius constellation in the southern horizon.
- Comet C/2025 A6 (Lemmon):
- Brighter of the two, with a magnitude of 4.5, near visual threshold.
- Can be seen near the Bootes constellation, close to the Big Dipper.
- Expected to return only in 3175, making this appearance a once-in-a-millennium event.
About Comets:
- What They Are?
- Comets are cosmic snowballs made of frozen gases, dust, and rocky material that orbit the Sun. When heated by sunlight, they release gases and form a glowing coma and tail.
- How They Occur?
- Most originate from two distant reservoirs:
- The Kuiper Belt — source of short-period comets (orbit < 200 years).
- The Oort Cloud — home of long-period comets, which may take millions of years to complete an orbit.
- Features:
- Nucleus: Frozen solid core of ice and dust.
- Coma: Cloudy atmosphere formed when ice vaporizes near the Sun.
- Tails: Two distinct tails — a dust tail and an ion tail — that always point away from the Sun.
- Importance: Comets are remnants from the solar system’s formation (4.6 billion years ago) and may have delivered water and organic compounds to early Earth, aiding life’s origin.
- Naming: According to the International Astronomical Union (IAU), comets are named after their discoverer(s) or the spacecraft/instrument that first detected them — e.g., Comet NEOWISE, Comet Lemmon, or Comet SWAN.
- Most originate from two distant reservoirs:
