A guide to what's up in the sky for Southern Australia

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Colliding Galaxies in Ara (1st Aug 2026)

ESO138-29 - Colliding Galaxies in Ara Right Ascension: 17:29:12 Declination: -62:27:35

Requiring a large telescope to observe it, the "Sacred Mushroom" galaxy is a rare collisional ring galaxy system located 111 million light years away in the southern constellation of Ara, the altar.

Nicknamed for its distinct celestial shape, the system features a glowing ring forming the "cap" and an elongated companion galaxy stretching out like a "stalk". The system was created when a
smaller intruder galaxy plunged directly through the centre of a larger target galaxy. This "bullseye" encounter sent powerful density waves rippling outward, creating a glowing circular ring of
mostly old, reddish stars.

The smaller companion galaxy remains visually connected to the ring via a bridge of gas and stars, giving the pair a distinctly mushroom-like profile. The stellar disk of the “cap” spans
approximately 150,000 light years across.