Astronomy

3. equinox, when the Sun crosses the celestial equator moving south, marking the start of autumn in the Northern Hemisphere (and spring in the Southern).
5. effect, the change in the wavelength of light from a celestial object due to its motion relative to Earth
6. moon, the phase of the moon when it is in conjunction with the sun and invisible from earth, or shortly thereafter when it appears as a slender crescent.
10. the time it takes for half of a radioactive substance to decay into a different element.
13. moon, It happens when Earth's shadow completely covers the full moon, filtering sunlight through our atmosphere and turning the lunar surface deep red or coppery brown.
14. the study
15. when one celestial body blocks the light from another
16. everything in the universe beyond Earth's atmosphere

1. ring effect,a stunning, brief visual phenomenon seen just before and after a total solar eclipse, resembling a sparkling diamond on a ring, caused by the last/first sunlight glinting through lunar valleys as the Sun's corona emerges/disappears, often preceded by Baily's Beads.
2. the innermost, darkest part of a shadow where a light source (like the Sun) is completely blocked by an opaque object (like the Moon or Earth), creating total darkness for observers within it
4. instrument that uses lenses or mirrors to make far-away objects look bigger, closer, and brighter
7. third planet from the sun
8. a huge collection of stars, dust and gas.
9. belt, a donut-shaped ring of icy bodies, like Pluto, that exists beyond Neptune's orbit in the outer solar system, filled with remnants from the solar system's formation, including comets and dwarf planets, making it a vast reservoir of frozen objects.
11. An easily recognized group of stars that appear to be located close together in the sky and that form a picture if lines connecting them are imagined
12. a small, icy object that orbits the sun and has a long "tail" of gas.