ISS

The International Space Station, a spacecraft orbiting Earth that can be visible from the ground during some passes.

APOD

Astronomy Picture of the Day, a daily NASA astronomy image/video with explanation.

Seeing

How stable the atmosphere is. Better seeing means steadier, sharper telescope views.

Transparency

How clear the sky is for deep-sky observing. Haze and humidity reduce transparency.

Moon Phase

The current illuminated shape of the Moon as seen from Earth.

Sky Brightness (mag/arcsec^2)

A measure of night-sky brightness at zenith. Higher values generally mean darker skies.

Bortle (Approx.)

A rough guide to light pollution level. In Stellara it is shown as an approximation from atlas data.

TLE

Two-Line Element data used to calculate a satellite orbit, including ISS tracking.

AI Assistant

Stellara's built-in assistant for astronomy questions, based on your context and current conditions.