sky-watch

name	sky-watch
description	Write a forward-looking asteroid watch — which near-Earth objects pass in the next few days, which is closest, and whether NASA has flagged any as dangerous — by running this skill's bundled script, never from memory. Use it whenever the user asks what asteroids are coming, wants a sky watch or asteroid forecast, asks whether anything is going to hit or come close to Earth, or runs a scheduled job that reports on near-Earth objects. A watch warns before the pass, so always look ahead, never report a pass that has already happened.
allowed-tools	Bash, Read

Sky watch

A watch earns its name by warning you before something happens, not after. So this skill always looks ahead — the next several days of asteroid close approaches — and never reports a pass that is already in the past. "Yesterday an asteroid nearly hit us" is a fact with no use in it.

The numbers are not guessable. Asteroid orbits are known, so NASA can say where the rocks will be — but only NASA can. So the position always comes from the bundled script, run fresh, every time.

Getting the forecast

Run the script:

python3 .claude/skills/sky-watch/scripts/skywatch.py

It fetches the next seven days of close approaches and prints a watch card: what is coming, the single closest pass, and — first, if any — the objects NASA has flagged as potentially hazardous. The script owns the API, the date window, and the danger check, so none of that has to be remembered.

Match the window to how often you run. Add --days N to narrow it:

python3 .claude/skills/sky-watch/scripts/skywatch.py --days 1   # today only

A daily watch should report today (--days 1) — if it sent the whole next seven days every morning, six of them would just repeat yesterday. Use the full seven-day window (the default) for a by-hand "what is coming this week?" or a weekly schedule. So: run daily, report today; run weekly, report the week.

For the raw numbers to reason with, ask for JSON:

python3 .claude/skills/sky-watch/scripts/skywatch.py --json

When you are emailing the watch, use the HTML card as the email body — it draws each pass as a proximity bar, closest first, so the reader sees the sky at a glance:

python3 .claude/skills/sky-watch/scripts/skywatch.py --html

Pass its output as the htmlBody of the email, and keep your one-line summary as the plain-text body. Do not hand-write HTML — the script's card is deterministic and email-safe; your job is still the framing sentence.

Writing the watch

Turn the card into one short, forward-looking paragraph a person can read over coffee and know whether to care. The shape:

1. Lead with danger, or with calm. If anything is flagged hazardous and actually close, say so first and plainly. If nothing is a real threat — the usual case — open by saying so. Do not bury "all clear" under a list.
2. Name the closest pass, in Moons. "23× the Moon's distance" means something; "8,918,882 km" does not. The script gives you both — use the Moon.
3. Say when. A watch is about the future, so dates matter: "on the 20th", "later this week".

Example — a calm week:

Sky watch for the week ahead: nothing to worry about. Forty asteroids pass in the next seven days, and the closest, 2019 NG2 on the 20th, stays 23 times farther than the Moon. Two are on NASA's "potentially hazardous" list, but both pass beyond 170× the Moon — that label is about their orbits, not this trip. All clear.

Example — the rare loud morning:

⚠ Heads up: 2024 XY passes on the 22nd at just 1.8× the Moon's distance and is on NASA's hazardous list — the closest approach this month by far. It will miss, but it is worth watching. The rest of the week is quiet.

One nuance to get right

"Potentially hazardous" is a classification of the object's orbit (it can come within ~7.5 million km and is over ~140 m wide), not a claim that this pass is dangerous. An object can carry the flag and still miss by 180× the Moon, as most do. Always report the flag and the actual distance, so the reader sees the difference. Never turn a routine flagged pass into a scare.

When the fetch fails

The script exits non-zero and says so. Say the watch could not run this time, in one line, and stop. Do not fill the sky with a remembered or guessed forecast — a false "all clear" is the one thing a watch must never say. The next scheduled run will try again.