Space

4. A set of interacting or interdependent component parts forming a complex whole, like the Solar one
10. A celestial body moving in an elliptical orbit round a star
11. The branch of science that studies celestial objects, space, and the physical universe
12. The emission of energy as electromagnetic waves or as moving subatomic particles
13. The total or partial obscuring of one celestial body by another
16. Tiny particles of matter floating in space, often found in nebulae
19. Having the shape of a flattened circle or oval
22. The distance light travels in one vacuum year, roughly 9.46 trillion kilometres
23. The lightest and most abundant chemical element in the universe
24. A group of stars forming a recognisable pattern that is traditionally named after its apparent form
25. A fixed luminous point in the night sky which is a large, remote incandescent body like the sun

1. The force that attracts a body toward the centre of the earth or toward any other physical body having mass
2. An imaginary line about which a body rotates
3. The envelope of gases surrounding a planet or other celestial body
5. A massive system of stars, gas, and dust held together by gravitational attraction
6. A colourless, odourless flammable gas which is the main constituent of natural gas and found on planets like Neptune
7. The curved path of a celestial object around a star, planet, or moon
8. A celestial object consisting of a nucleus of ice and dust and, when near the sun, a “tail” of gas and dust particles
9. A small body of matter from outer space that enters the earth's atmosphere, becoming incandescent as a "shooting star"
10. An unmanned exploratory spacecraft sent to transmit data from space
14. An artificial body placed in orbit round the earth or another planet in order to collect information or for communication
15. A drawing that represents an object or area with sizes in perfect proportion to the original
17. All existing matter and space considered as a whole; the cosmos
18. A repeated decorative design or a regular sequence of events
20. A cloud of gas and dust in outer space, visible in the night sky as a bright patch or dark silhouette
21. A small, rocky body orbiting the sun, mostly found between Mars and Jupiter