The time elapsed since the last new moon. It is calculated in days, hours and minutes.
Height of an object or point on Earth measured above sea level. Wikipedia
Angular Diameter (Sun, Moon)
The apparent (visual) size of an object measured as an angle from a given position. The angular diameter of the sun and moon are almost identical seen from anywhere on Earth, being of a value close to 0.5º. Wikipedia
Annular solar eclipse
Also known as gegenschein, it is a weak luminosity visible in night skies in the direction of the ecliptic, but in the opposite direction to the sun. Wikipedia
The furthest point of orbit of an object measured from the Earth. Wikipedia.
An astronomical season is the period of time with beginning and end marked by equinoxes and solstices. The four astronomical seasons in the northern hemisphere are:
- Spring: from the March equinox to the June solstice.
- Summer: from the June solstice to the September equinox.
- Autumn: from the September equinox to the December solstice.
- Winter: from the December solstice to the March equinox.
In the southern hemisphere:
- Autumn: from the March equinox to the June solstice.
- Winter: from the June solstice to the September equinox.
- Spring: from the September equinox to the December solstice.
- Summer: from the December solstice to the March equinox.
Solar twilight phase. It is the darkest phase of the three twilight phases that occurs when the sun is between 12º and 18º below the horizon and when it is still dark enough to see at a glance all astronomical observations such as the arc of the Milky Way or the galactic center. It is also the earliest phase of dawn and the later phase of dusk. Time and date / Wikipedia.
Time the Earth needs to complete an orbit around the sun. Its duration varies from year to year, the average is approximately 365 days, 5 hours, 48 minutes and 45 seconds (365.24219 days). Also known as astronomical year, equinoctial year. Time and Date
Aurora Borealis and Aurora Australis
Also known as Northern Lights in the Northern Hemisphere and Southern Lights in the Southern Hemisphere. They are natural phenomena that create bright colored lights in the sky. Time and Date
Angle measured around the observer’s horizon from the geographic north to the celestial body in the direction of the clockwise. A celestial body above the geographical north will have an azimuth of 0º, if it is east 90º, to the South 180º and to the west 270º (or -90º). Time and Date/ Wikipedia.