Measuring time by the Sun the Moon and the Stars

Motion and Time of Class 7

Measuring time by the Sun the Moon and the Stars

As the sun moves across the sky, shadows change in direction and length, so a simple sundial can measure the length of a day. It was quickly noticed that the length of the day varies at different times of the year. The reasons for this difference were not discovered until after astronomers accepted the fact that the earth travels round the sun in an elliptic orbit, and that the earth's axis is tilted at about 26 degrees. This variation from a circular orbit leads to the Equation of Time (see 'Note 2' below) which allows us to work out the difference between 'clock' time and 'sundial time'.

Another discovery was that sundials had to be specially made for different latitudes because the Sun's altitude in the sky decreases at higher latitudes, producing longer shadows than at lower latitudes. Today, artists and astronomers find many ways of creating modern sundials.

measuring time nomenclature

Inventions for measuring and regulating time

The early inventions were made to divide the day or the night into different periods in order to regulate work or ritual, so the lengths of the time periods varied

greatly from place to place and from one culture to another.

NCERT SOLUTION FOR CLASS-7 SCIENCE (Science for grade-7 NCERT solutions)

NCERT Solution for Class 7 Science Chapter 1 - Nutrition in Plants

NCERT Solution for Class 7 Science Chapter 2 - Nutrition in Animals

NCERT Solution for Class 7 Science Chapter 3 - Fibre to Fabric

NCERT Solution for Class 7 Science Chapter 4 - Heat

NCERT Solution for Class 7 Science Chapter 5 - Acids, Bases and Salts

NCERT Solution for Class 7 Science Chapter 6 - Physical and Chemical Changes

NCERT Solution for Class 7 Science Chapter 7 - Weather, Climate and Adaptations of Animals to Climate

NCERT Solution for Class 7 Science Chapter 8 - Winds, Storms and Cyclones

NCERT Solution for Class 7 Science Chapter 9 – Soil

NCERT Solution for Class 7 Science Chapter 10 - Respiration in Organisms

NCERT Solution for Class 7 Science Chapter 11 - Transportation in Animals and Plants

NCERT Solution for Class 7 Science Chapter 12 - Reproduction in Plants

NCERT Solution for Class 7 Science Chapter 13 - Motion and Time

NCERT Solution for Class 7 Science Chapter 14 - Electric Current and Its Effects

NCERT Solution for Class 7 Science Chapter 15 – Light

NCERT Solution for Class 7 Science Chapter 16 - Water: A Precious Resource

NCERT Solution for Class 7 Science Chapter 17 - Forests: Our Lifeline

NCERT Solution for Class 7 Science Chapter 18 - Wastewater Story

Talk to Our counsellor