Study: Days Were Shorter Millions of Years Ago

Category : Science/Environment

Unlocking Word Meanings

Read the following words/expressions found in today’s article.

  1. roam / roʊm / (v) – to go to different places randomly

    We couldn’t leave our house because some wild animals were roaming the streets.

  2. axis / ˈæk sɪs / (n) – the line around which a heavenly body turns

    It takes the sun more than 20 days to rotate on its axis.

  3. revolution / ˌrɛv əˈlu ʃən / (n) – the movement of an astronomical object around another

    One complete revolution of the Earth around the Sun takes around 365 days.

  4. friction / ˈfrɪk ʃən / (n) – a power or force created when two things are touching each other

    Rubber shoes create friction with the floor.

  5. fossilized / ˈfɒs əˌlaɪzd / (adj) – preserved to become an object from the past

    Scientists discovered fossilized animal bones inside the cave.


Read the text below.

A recent study revealed that days 70 million years ago were shorter than they are now.

When dinosaurs roamed the Earth millions of years ago, the planet was rotating faster than it does at present, according to the results of the study. The findings revealed that the Earth previously rotated around its axis 372 times per year as compared to 365 times today. This means that millions of years ago, there were only 23.5 hours in a day.

Despite the decrease in the number of the Earth’s rotations, the researchers explained that the Earth’s revolution around the Sun remained constant throughout the years. However, the length of one day has increased because of friction from ocean tides. This friction slows the Earth’s spinning.

For the study, the researchers examined a fossilized mollusk that lived 66 million years ago but is now extinct. The aquatic creature had a shell with growth rings. These rings represented the creature’s growth in a single day.

Using lasers, the researchers analyzed the growth rings. The analysis helped them determine the length of one day during the period when the mollusk lived. Seasonal patterns in the shell also helped the researchers identify the exact years when the creature lived.

By examining the mollusk, the researchers also discovered the Earth’s temperature and water composition millions of years ago. The results of the examination revealed that the temperature before was warmer than what scientists had believed.

The researchers said that their analysis can also give insight into how often extreme climate events occurred in the past and provide information about the Earth’s previous weather conditions.

Viewpoint Discussion

Enjoy a discussion with your tutor.

Discussion A

• Do you think it is possible for scientists to discover the precise condition of the Earth millions of years ago? Why or why not?
• Do you think learning about the Earth’s weather patterns in the ancient past is still relevant? Why or why not?

Discussion B

• Aside from the Earth’s rotation and temperature, what other things in ancient times should scientists study about (e.g. species, landforms)? Discuss.
• What changes do you think will happen to the Earth in the future (e.g. rise in temperature, decrease in land area)? Discuss.

Category : Science/Environment