Grade 5 · Unit 6: Earth’s movements
The Earth revolves around the Sun
One trip round the Sun is one year.
A year-long journey
As well as spinning, the Earth revolves (travels) round the Sun. One full orbit takes about 365¼ days. This is one year. The Earth travels about 940 million km in one orbit!
The Earth travels round the Sun at about 30 km every second – more than 100 times faster than a jet plane.
Leap years
Our calendar has 365 days, but the orbit takes 365¼ days. The extra quarter days add up to one whole day every four years. So every fourth year is a leap year, with 29 days in February.
Years that can be divided by 4 are usually leap years, such as 2024 and 2028.
Why we have seasons
Because the Earth’s axis is tilted, different parts lean towards the Sun at different times of year. When our part leans towards the Sun, the Sun is higher, days are longer, and it is summer. When it leans away, days are shorter and it is winter.
In June, the Sun is high over Bangladesh and the days are long. In December, the Sun is lower and the days are shorter, so it is cooler.
Seasons in Bangladesh
Bangladesh has six traditional seasons: summer, monsoon, autumn, late autumn, winter and spring. Monsoon rains come from moist winds, but the temperature changes come from the Earth’s tilt.
The six seasons are grishma (summer), barsha (monsoon), sharat (autumn), hemanta (late autumn), sheet (winter) and basanta (spring).
What I learnt
- I know that the Earth revolves round the Sun once a year.
- I can explain leap years and why we have seasons.