Simulasi Astronomi

Explore Kepler’s three laws of planetary motion. Adjust semimajor axis and eccentricity, watch equal-area sweeps, and visualize velocity and acceleration vectors.

A background star or galaxy lensed by a point mass. Observe Einstein rings, double images, arcs, and magnification as a function of impact parameter.

Point mass and binary lens on the observer’s sky. Explore critical curves and caustic structure as star-planet mass ratio and separation change.

Earth’s orbit shifts nearby stars against the background. Explore the parallax ellipse, parsec definition, and how ecliptic latitude shapes the apparent path.

Explore right ascension and declination on the celestial sphere. Drag the star to any position, see RA and dec arcs, toggle the ecliptic, equator, and pole labels.

See how sidereal time and right ascension determine the hour angle of a star. Adjust observer latitude, sidereal time, and star coordinates on the 3-D celestial sphere with local horizon.

Compare equatorial, ecliptic, and galactic coordinates on one sphere. Enable systems to overlay their great circles and poles, and see the spherical triangles that connect them to the star.

Horizon diagram showing how the sun moves across the sky throughout the day and year. Adjust date, time, and observer latitude; watch the declination circle, ecliptic, and analemma.

Why the Sun traces a figure-eight. Turn obliquity, eccentricity and the longitude of perihelion, and watch the equation of time split into the two effects that build the shape — on any of the eight planets, from Mars’ teardrop to Uranus’ bowtie.

Follow a relativistic jet's wavefronts to see why its Earth-observed sky motion can appear faster than light without breaking relativity.

A star’s neighbour sees its companion orbit at a steady rate; Earth, far away, sees each orbit compressed then stretched as the light path shortens and lengthens. Wavefronts plus an O−C-style timing plot.

Why astronomers live on log paper. Kepler’s third law, mass–luminosity, Cepheid P–L, Tully–Fisher, Faber–Jackson, M–σ and more — toggle each axis lin / log and watch every power law animate from a curve into a straight line whose slope is its exponent.

Horizontal, vertical, and equatorial sundials with live gnomon shadow. Change date, time, and latitude; compare indicated solar time to the hour lines.

The observer’s motion tilts every star toward the apex. Vary β = v/c from Earth’s real 20.5″ up to the relativistic regime, and watch each star trace its yearly aberration ellipse.

Explore the Planck radiation spectrum for thermal sources. Adjust temperature to see Wien's law and total flux, and calculate approximate theoretical magnitudes across U, B, V, R filters.

HR-diagram evolution tracks and cluster isochrones from the Hurley et al. (2000) SSE analytic model — scrub any star from ZAMS through giant phases to its remnant.

A live, drag-to-rotate dome of the real night sky for any place and time — naked-eye stars, constellations, and the Sun, Moon, and planets from an embedded star catalog and analytic ephemeris.

A flat, drag-to-rotate planisphere — zenith at the center, horizon at the rim, modeled on classic star-wheel charts. Stars, constellations, deep-sky objects, the Milky Way band, and live coordinate readout.