Sky Above
Altitude · Airmass over the night
Altitude on the y-axis · time UTC on the x-axis · twilight bands shaded · vertical line is the current time.
What's Up Right Now
Brightest objects above the horizon at the current time. Updates as you scrub the slider or hit play. Filtered by your Bortle / magnitude cutoff.
Location & Time
UTC—
Local—
LST—
Sun · Moon—
Sky Conditions · Light Pollution
Slide the Bortle scale from a perfect dark site (1) to inner-city skies (9). Watch the stars disappear. Bortle controls the limiting naked-eye magnitude — you can also override it manually below.
3 — Rural
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Truly dark site. Milky Way casts shadows. Limit ≈ mag 7.0.
7.0
Stars fainter than this cutoff are hidden. The lower the value, the more washed-out your sky.
— stars currently visible
Coordinate Search
Drop a target on the sky. Accepts a
J-name (e.g. J231402.98+265807.3), sexagesimal (03:14:59.99 +27:16:00), or decimal degrees (48.75 27.27).Overlays
Toggle the layers. The hover-tip on each one tells you what it represents on the dome.
What you're looking at
Planisphere view. The full dome of sky overhead is squashed flat onto a circle. The center is the zenith (straight up), the rim is the horizon, and the four cardinal directions sit on the rim. A star at altitude 60° is one third of the way from the rim to the center.
Why does the sky turn? The Earth is rotating under it. Press play and you'll see stars trace circles around a pole — in the Northern hemisphere, they all wheel around Polaris. The Sun and Moon also rise in the east and set in the west, but the Moon drifts ~13°/day eastward against the stars.
Why do the planets stay near the ecliptic line? The solar system is roughly flat. Mercury, Venus, Mars, Jupiter, Saturn — their orbits are nearly co-planar with Earth's, so from our vantage point they stay close to the same arc. That arc is the ecliptic.