Science is, to a large extent, what makes our modern world modern. Yet many of us are not sure how it works or why it matters.

Science provides the basis of practical fields such as medicine and engineering, and offers hope that many of the existing problems or looming emergencies can be solved. Science can also provide universal truths that are based on the facts, and not on preconceptions or other beliefs. Science is conducted for the benefit of the human race and the planet we live on, although some studies might not seem to have immediate benefit.

Because science exists to serve the public, and depends on public support, the goal of this year-long celebration is to enhance public opportunities to understand science and to participate in it.

The other reason for designating 2009 as the Year of Science is history. Modern science depends on old science, and this year we celebrate some big discoveries of the past that brought us to the current astonishing changes in medicine, environment, space science, earth history, the microscopic world, ancient history, biodiversity, understanding the brain and many other topics.

It was exactly 400 years ago that Galileo used a telescope to discover numerous faint stars in the constellation Orion and in the Pleiades star cluster, and then used it to find four moons circling the planet Jupiter. You can see them yourself, with binoculars. Jupiter, along with Venus and Mercury, can be found in the southwest for the next few weeks, right after sunset.

In the same year, 1609, Johannes Kepler published his calculations and laws of planetary motion, showing that the orbit of a planet is an ellipse with a star (like the Sun) at one focus. It seems amazing that great scientists of the past were able to make such progress, considering the very limited tools they had, but also because of cultural and political distractions. Around this time, Kepler's wife and four children died of diseases, including smallpox. He had to take leave from his work to go to court to defend his mother on a charge of witchcraft, for which she faced execution. Fortunately, science has improved these conditions since then, as well.

In 2009, we will also celebrate the 200th anniversary of the birth of Charles Darwin, the most important biological scientist in history. His famous book, "The Origin of Species," explaining the simple process that results in genetic change over time and the appearance of new species from previous ones, was published 150 years ago.

The world-famous fossil deposits at Burgess Shale (Yoho National Park, near Field, B.C.) were discovered by paleontologist Charles Walcott exactly 100 years ago. The soft-bodied animals in the rocks lived over 500 million years ago, before animals with backbones existed. I have visited the Burgess Shale and recommend it to anyone who wants to combine appreciation for science and mountain hiking (check in advance the Burgess Shale Foundation regarding access). The story of the Burgess Shale was made more famous in Stephen Jay Gould's book, "Wonderful Life."

Finally, science can also be great fun and liberating. The methods of science are not secret or elitist. Even though not everyone is in a position to work as a professional scientist, everyone can live scientifically, by thinking about how we come to know things, and stopping to weigh the evidence before determining what to conclude or believe.

Groups such as the Coalition on the Public Understanding of Science (COPUS) will be providing websites and information on Year of Science events to make science accessible and exciting.

Dan Johnson is professor of Environmental Science and Canada Research Chair (Evolution and Ecology) at the University of Lethbridge.