Across
- 1. is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets.
- 7. is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It only has one-eighth the average density of Earth; however, with its larger volume, Saturn is over 95 times more massive.
- 10. is a modular space station in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA, Roscosmos, JAXA, ESA, and CSA.
- 11. is Earth's only natural satellite. At about one-quarter the diameter of Earth, it is the largest natural satellite in the Solar System relative to the size of its planet, the fifth largest satellite in the Solar System overall, and is larger than any known dwarf planet.
- 13. is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus, who, according to Greek mythology, was the great-grandfather of Ares, grandfather of Zeus and father of Cronus. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System.
- 14. is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, the dwarf planets and small Solar System bodies.
- 17. is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member aboard a spacecraft.
Down
- 2. is the European Space Agency's ground based observatory at the Teide Observatory on Tenerife, Spain, built for the observation of space debris. OGS is part of the Artemis experiment and is operated by the IAC and Ataman Science S.L.U.
- 3. is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km, which is about 20% of Earth's radius or 70% of the Moon's radius. There are no samples of Earth's core accessible for direct measurement, as there are for Earth's mantle
- 4. is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth the mass of the Sun.
- 5. is a robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed Curiosity, a Mars rover, in Gale Crater on August 6, 2012.
- 6. is the second planet from the Sun. It is named after the Roman goddess of love and beauty. As the brightest natural object in Earth's night sky after the Moon, Venus can cast shadows and can be, on rare occasions, visible to the naked eye in broad daylight.
- 8. is the third planet from the Sun and the only astronomical object known to harbor and support life. About 29.2% of Earth's surface is land consisting of continents and islands. And the planet we live in
- 9. was a partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration as part of the Space Shuttle program.
- 12. is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy mainly as visible light, ultraviolet light, and infrared radiation.
- 15. is an object that has been intentionally placed into orbit. These objects are called artificial satellites to distinguish them from natural satellites such as Earth's Moon. On 4 October 1957, the Soviet Union launched the world's first artificial satellite, Sputnik 1.
- 16. is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It was the first and the largest Kuiper belt object to be discovered. After Pluto was discovered in 1930, it was declared to be the ninth planet from the Sun.
- 18. is the eighth and farthest known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, slightly more massive than its near-twin Uranus.