Numbers in the News: Microbes

September 17 is International Microorganism Day. Check out some facts and figures about microbes—organisms usually too tiny to see with the naked eye!

NEW YORK PUBLIC LIBRARY/SCIENCE SOURCE

1673

The year Dutch scientist Antonie van Leeuwenhoek made the first observations of microbes. He used a homemade microscope!

40 TRILLION

The number of microbes living in or on your body—slightly outnumbering your human cells.

EYE OF SCIENCE/SCIENCE SOURCE

1,000

The estimated number of flu viruses that would fit in the width of a human hair. Viruses are the smallest type of microbe.

3.5 BILLION YEARS

The age of the oldest known microbes. They were preserved in fossils and represent some of the earliest evidence of life on Earth.

KATERYNA KON/SCIENCE SOURCE

1 CENTIMETER

The average length of Thiomargarita magnifica, the largest known bacteria.

TAKE IT FURTHER: People rely on microbes to make bread, chocolate, cheese, and yogurt. Pick one of these foods and find out how microbes are involved in its creation.

SOURCES: NATIONAL HUMAN GENOME RESEARCH INSTITUTE, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES (2017), NATIONAL INSTITUTES OF HEALTH, NATURE (2022)

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