Sky calendar

Past events

• Orionids · the night of October 21–22, 2026

  The Orionids peak on the night of October 21–22, 2026.

• 10 October 2026: New moon

• 4 October 2026 · 14:25: Saturn at opposition

What affects visibility of sky phenomena

Phases change the lit portion of the disk

Lunar phases arise as our view of the Moon's sunlit half changes. Near new moon, moonlight interferes less with faint objects, but the Moon's altitude also matters.

NASA · lunar phases

Elongation and opposition help choose a time

Elongation is a planet's angular separation from the Sun in the sky. At opposition an outer planet lies opposite the Sun, allowing night-time observation when the horizon and weather permit.

NASA/JPL · elongation

Magnitude describes brightness, not guaranteed visibility

Apparent magnitude describes an object's brightness for an observer. A lower value means a brighter object, but sky brightness and atmospheric transparency also affect visibility.

ESO · magnitude

The radiant gives a direction, ZHR compares activity

A meteor shower occurs when Earth passes through a meteoroid stream. The radiant is the direction from which their paths appear to diverge, not where all meteors will be seen.

IMO · showers and ZHR

ZHR is not a meteor count for your site

ZHR is the zenithal hourly rate referenced to a radiant at the zenith, an unobstructed view and a stellar limiting magnitude of +6.5. A lower radiant, moonlight, clouds and light pollution reduce observed counts.

IMO · ZHR definition

Occultations and eclipses have different geometry

In an occultation, a nearer body passes in front of and hides a more distant one. In a lunar eclipse the Moon passes through Earth's shadow, while in a solar eclipse it covers the Sun's disk for part of Earth.

NASA · eclipses

Altitude and azimuth belong to a place and time

Altitude alt is the angle above the geometric horizon, while azimuth az gives the direction from north through east. Refraction changes apparent altitude, especially near the horizon, and depends on the atmosphere. The map does not replace a view past real terrain.

NASA/JPL · alt/az and refraction

Astronomical twilight has a geometric boundary

Evening astronomical twilight ends and morning astronomical twilight begins when the Sun's centre is geometrically 18° below the horizon. Astronomical night alone does not guarantee a dark sky free of moonlight, clouds or light pollution.

USNO · twilight

Choose constellations for the selected time

Earth's rotation changes the direction of stars during the night. Its orbit around the Sun changes the sky available in the evening through the year, so the map needs a place and time.

NASA · constellations

Bortle describes sky conditions

Light pollution brightens the background and reduces the contrast of faint objects. The Bortle scale describes night-sky conditions, but this map does not determine your site's Bortle class. Protect dark adaptation from bright screens and direct light.

NASA · dark skies

NASA · opposition · NASA · lunar occultation