Astronomy Glossary

Solar System

The ecliptic is the apparent path of the Sun across the celestial sphere over a year, representing Earth's orbital plane projected onto the sky.

Galaxies

Elliptical galaxies are smooth, featureless systems ranging from nearly spherical to highly elongated, containing predominantly old stars with little ...

Astronomy Concepts

Emission lines are bright lines at specific wavelengths in a spectrum, produced when excited atoms/ions emit photons.

Telescopes Equipment

Equatorial mounts align one axis parallel to Earth's rotation axis, allowing simple tracking of celestial objects with single-axis motion.

Astronomy Concepts

An equinox occurs when the Sun crosses the celestial equator, making day and night approximately equal length everywhere on Earth.

Cosmology Universe

The expansion of the Universe is the increase in distance between galaxies over time, a fundamental prediction of General Relativity and observational...

Telescopes Equipment

An eyepiece is the small optical system at the telescope's focus that magnifies the image for viewing, essentially a sophisticated magnifying glass.