CometCat — amateur astronomy & comets

Notebook entry · this month

Comet of the month

One comet worth losing a little sleep over, picked from this month’s sweep of the evening and morning sky.

C/2025 M3 (Panstarrs)

A long-period visitor on its one recorded pass through the inner sky — the previous approach, if the old orbital solutions are right, was well over three thousand years ago. This month it glides through Auriga in the hours before dawn, and it is quietly having its best two weeks.

In 10×50 binoculars it shows as a soft, slightly lopsided smudge about the size of the Moon’s disc; my small reflector adds a short tail pointing away from the Sun and a faint greenish core. It will fade slowly from here, so pick a clear morning soon — and check the Moon below before you go. Faint fuzzies and moonlight do not mix.

mag ≈ 6.3
constellation: Auriga
tail ≈ ½°
best: 2–4 a.m.

Live, from your clock

Tonight’s Moon

The phase below is computed in your browser from the real date and time. No services called, nothing sent anywhere — just arithmetic.

— computing —

– % illuminated

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The wall above the desk

Photo wall

Real captures from rooftops, balconies and one very patient tripod.

A stargazer silhouetted on a ridge under the Milky Way during the Perseids — Perseids from the ridge 24 × 15 s stacked, ISO 3200 — the Milky Way stayed all night

Comet C/2023 A3 with a long tail over a twilight shoreline — Comet C/2023 A3 over the water 15 October 2024 — the evening it was easiest, 4 s on a tripod

The Milky Way arcing over a walkway railing with two silhouetted stargazers — Milky Way from the reservoir walkway 20 s, f/2.0, 14 mm — two strangers stayed for the whole show

Sequence of a red total lunar eclipse from first bite to totality — Total lunar eclipse, first bite to totality 3 March 2007 — shot through closed glass, patience, not bravery

Saturn with its wide rings and three moons — Saturn in a good year webcam through the 114 mm reflector, best 400 frames stacked

A magenta aurora glow with the Moon low over the horizon — The night the alerts were right 10 May 2024, 22:42 — the G5 storm reached the village

Photo credits: Giles Laurent (CC BY-SA 4.0) · King of Hearts (CC BY-SA 4.0) · ESO/L. Calçada & H. Zodet (CC BY 4.0) · Georgfotoart (CC BY-SA 4.0) · Giuseppe Donatiello (CC0) · NASA/JPL (public domain).

Interactive · drawn from the notebook

Star map

Six favourites, drawn from my own notebook coordinates. Hover, tap or Tab to them — each one hides a story.

The rooftop community

Forum

Skies, gear and one unstoppable cat — 42 members, 61 threads, 402 posts. Previews are open; threads and replies are for signed-in members.

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