$$\require{cancel}$$

# 1.27 Astronomy as a Science

Astronomy is the science that deals with the nature of the universe we live in. The evidence shows that human are not in a central or unique position, but just part of a vast system. Scientists have discovered that a small number of physical rules govern the behavior of everything from the Earth's atmosphere to the whole universe during the big bang. In a general sense, astronomy is the application of physics to the universe beyond the Earth. We are depending on the fact that the laws of physics apply in remote regions of time and space, an assumption that has been confirmed whenever we can test it.

Photograph of the Milky Way in the night sky over Black Rock Desert, Nevada taken on 7/22/2007. It is a 54 second exposure taken with a tripod mounted Cannon EOS 5D digital camera with a 16mm lens, wide open at f2.8 and ISO800. Click here for original source URL.

All ideas in science are based on evidence and are subject to review and revision. Evidence is presented in the form of a quantitative measurement, which consists of a number, a system of units, and an error or uncertainty in the number. Using such measurements, scientists make a working hypothesis based on observations and then try to verify or disprove it with more observations. Ideas that survive this skeptical approach become known as theories. A good theory is testable, makes predictions, and explains a wide range of phenomena. Theories are not immutable. The history of science has seen theories modified and overthrown. Such an outcome is not a weakness or a failure of science; it's how we make progress in understanding nature. Scientific ideas can be expressed either in words or in equations. The tools for manipulating these ideas are logic and mathematics.

NASA's?Hubble Space Telescope took the picture of Mars on June 26, 2001, when Mars was approximately 68 million kilometers (43 million miles) from Earth ? the closest Mars has ever been to Earth since 1988. Hubble can see details as small as 16 kilometers (10 miles) across. The colors have been carefully balanced to give a realistic view of Mars' hues as they might appear through a telescope. Especially striking is the large amount of seasonal dust storm activity seen in this image. One large storm system is churning high above the northern polar cap (top of image), and a smaller dust storm cloud can be seen nearby. Another large dust storm is spilling out of the giant Hellas impact basin in the Southern Hemisphere (lower right). Click here for original source URL.

Good scientists know that they have no lock on the truth, and they recognize that any measurement is uncertain to some degree. For example, if we are still unsure whether or not life once existed on Mars, it is because the evidence is inadequate. This provides strong motivation for the planned set of space missions to return new rocks to Earth. Humans have invented many systems of thought over the centuries. These systems have their attractions, but they all have limitations for transmitting a coherent body of knowledge and for revealing the truth. The unique character of science is that it progresses toward amore accurate body of knowledge by gathering new data, testing hypotheses, and revising theories that don’t match observations.