Distinguish a natural satellite from an artificial satellite, using the Moon as the reference example.
Hint. One orbits Earth without any human involvement; the other is built and launched by people.
✦ The Moon is Earth's natural satellite — it orbits Earth without any human involvement. Artificial satellites are man-made objects sent up by various countries that also orbit Earth, appearing as tiny moving specks in the night sky, since they are man-made bodies distinct from the Moon.
State the typical altitude and orbital period of most artificial satellites.
Hint. Given directly in the chapter's opening paragraph on satellites.
✦ Most artificial satellites orbit about 800 km above Earth's surface and take roughly 100 minutes to complete one orbit.
List three ISRO missions or satellite series named in the chapter, along with what each one does.
Hint. The chapter names Earth-imaging, astronomy, and interplanetary missions.
✦ Any three of: the Cartosat series, which captures high-quality images of Earth to improve maps, plan cities and handle natural disasters (feeding the Bhuvan mapping platform); AstroSat, which makes scientific observations of stars and other celestial objects; Chandrayaan 1, 2 and 3 to the Moon; Aditya L1 to study the Sun; and Mangalyaan to Mars — because ISRO runs Earth-observation, astronomy and interplanetary missions together, plus student-built satellites like AzaadiSat, InspireSat-1 and Jugnu.
Describe how Activity 11.4 identifies an artificial satellite in the night sky, and what makes it distinguishable from a star or aircraft.
Hint. The chapter gives both the timing and the visual behaviour to look for.
✦ Just before sunrise or after sunset, from a location with an unobstructed view of the sky (accompanied by an adult), look for any moving object appearing as a point of light with steady or flickering brightness, moving very fast and steadily across the sky — visible with the naked eye or binoculars. Unlike a star, it visibly moves across the sky in real time; which is why tracking apps or websites can confirm exact satellite pass times for a given location.
A step further: what is space debris, and what happens to small versus large pieces of it as they fall back to Earth?
Hint. Two different fates depending on size — one burns up, one doesn't.
✦ Space debris (or space junk) consists of old satellites and rocket parts left in space after their useful life ends by the many countries launching satellites; this debris crowds space and could collide with working satellites. Small debris burns up in the atmosphere as it falls towards Earth, but larger pieces can survive re-entry and crash on the ground — which is why countries are now working together to remove this debris.
Be a scientist: who was Vikram Sarabhai, and what facility is named after him?
Hint. He is called by a specific title tied to India's space programme.
✦ Vikram Ambalal Sarabhai (1919–1971), a researcher in space science and nuclear physics, is known as the 'Father of the Indian Space programme' and pioneered the effort to launch India's first artificial satellites. The Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram — the ISRO centre that develops rockets and launch vehicle technology — is named after him because of that pioneering role.
Solutions written by the tuition.in editorial team and checked against NCERT Curiosity — Textbook of Science for Grade 8, Chapter 11 (hecu111.pdf), Reprint 2026-27, pages 170-189. Questions are referenced from the NCERT textbook for identification.
Pair self-study with a tutor, a live course or a coaching centre.
