Space Science and Exploration

Mars perhaps first caught public fancy in the late 1870s, when Italian astronomer Giovanni Schiapparelli reported using a telescope to observe canali, or channels, on Mars. A possible mistranslation of this word as canals may have fired the imagination of Percival Lowell, an American businessman with an interest in astronomy. Lowell founded an observatory in Arizona, where his observations of the red planet convinced him that the canals were dug by intelligent beings - a view which he energetically promoted for many years. By the turn of the century, popular songs told of sending messages between Earth and Mars by way of huge signal mirrors. On the dark side, H.G. Wells' 1898 novel The War of the Worlds portrayed an invasion of Earth by technologically superior Martians desperate for water. In the early 1900s novelist Edgar Rice Burroughs, known for the Tarzan series, also entertained young readers with tales of adventures among the exotic inhabitants of Mars, which he called Bars...

“I don’t know — when I was growing up, there was no such thing as planets around other stars. If you were to talk about it at a scientific meeting, people would laugh at you….” Oh, how times change. And so begins a new short documentary  by Goddard video producer Ryan Fitzgibbons and videographer Jamal Smith. 20 Years of Hubble Science: Exoplanets highlights the Hubble Space Telescope’s contributions to the study of planets around other stars. In the video, Goddard scientists Marc Kuchner , Aki Roberge , and Jennifer Wiseman  discuss how Hubble’s coronagraph and resulting images have helped scientists find exoplanets, dusty disks around other stars, and infant solar systems. All three astronomers are members of our Exoplanets and Stellar Astrophysics Laboratory . The science is at the leading edge and the graphics are awesome — especially the animated timeline showing all exoplanet discoveries to date. Go to the Scientific Visualization Studio website to download and view ...

A BRIEF HISTORY OF TIME  Stephen W. Hawking  Our Picture of the Universe  Any physical theory is always provisional, in the sense that it is only a hypothesis: you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation that disagrees with the predictions of the theory... Each time new experiments are observed to agree with the predictions the theory survives, and our confidence in it is increased; but if ever a new observation is found to disagree, we have to abandon or modify the theory. Today scientists describe the universe in terms of two basic partial theories - the general theory of relativity and quantum mechanics... The general theory of relativity describes the force of gravity and the large-scale structure of the universe, that is, the structure on scales fro...

The photoelectric effect refers to the emission, or ejection, of electrons from the surface of, generally, a metal in response to incident light.  Energy contained within the incident light is absorbed by electrons within the metal, giving the electrons sufficient energy to be 'knocked' out of, that is, emitted from, the surface of the metal.  Using the classical Maxwell wave theory of light, the more intense the incident light the greater the energy with which the electrons should be ejected from the metal. That is, the average energy carried by an ejected (photoelectric) electron should increase with the intensity of the incident light.  In fact, Lénard found that this was not so. Rather, he found the energies of the emitted electrons to be independent of the intensity of the incident radiation.  Einstein (1905) successfully resolved this paradox by proposing that the incident light consisted of individual quanta, called photons, that interacted with the electr...

We have all, at some time or another heard of black holes, but what exactly is a black hole and why is it ‘black’? As I described in my post about star types, most stars grow slowly into massive red giants as they run out of hydrogen. Most then collapse heating up in their final years. This collapse is halted quickly however as most stars don’t have enough mass to create a gravitational pull strong enough to overcome electron degeneracy pressure thus preventing further collapse. In simple terms this is the force that prevents electrons sticking to the protons in the nucleus of the atom. The star can’t release any more energy and it slowly loses its outer layers to space leaving a cooling white dwarf the size of Earth. More massive stars (those with more than 10 solar masses) continue gravitational collapse past electron degeneracy. This means that in the final moments of a massive star’s life it actually fuses electrons and protons together to form neutrons. This process releases mas...

Once a hypothesis has survived to test, it may become adopted into the framework of a scientific theory. This is a logically reasoned, self-consistent model, or framework for describing the behavior of certain natural phenomena. A theory typically describes the behavior of much broader sets of phenomena than a hypothesis; commonly, a large number of hypotheses can be logically bound together by a single theory. Thus a theory is a hypothesis explaining various other hypotheses. In that vein, theories are formulated according to most of the same scientific principles as hypotheses.

Unlike a mathematical proof, a scientific theory is empirical and is always open to falsification if new evidence is presented. That is, no theory is ever considered strictly certain. Instead, science is proud to make predictions with great probability, bearing in mind that the most likely event is not always what actually happens.  During the Yom Kippur War, cognitive psychologist Daniel Kahneman was asked to explain why one squad of aircraft had returned safely, yet a second squad on the exact same operation had lost all of its planes. Rather than conduct a study in the hope of a new hypothesis, Kahneman simply reiterated the importance of expecting some coincidences in life, explaining that absurdly rare things, by definition, occasionally happen. In this sense, probabilities can run counter to our intuitions, which rely heavily on heuristics including mental availability.

My philosophy of science seeks to understand the nature and justification of scientific knowledge. It has proven difficult to provide a definitive account of the scientific method that can decisively serve to distinguish science from non-science. Thus there are legitimate arguments about exactly where the borders are, which is known as the problem of demarcation . There is nonetheless a set of core precepts that have broad consensus among published philosophers of science and within the scientific community at large. For example, it is universally agreed that scientific hypotheses and theories must be capable of being independently tested and verified by other scientists in order to become accepted by the scientific community.

Science (from the Latin scienta meaning "knowledge") is, in its broadest sense, any systematic knowledge that is capable of resulting in a correct prediction or reliable outcome. In this sense, science may refer to a highly skilled technique, technology, or practice. In its more restricted modern sense, science is a system of acquiring knowledge based on scientific research, and to the organized body of knowledge gained through such research. Science in this modern sense is a systematic enterprise of gathering knowledge about the world and organizing and condensing that knowledge into testable laws and theories This article focuses on science in this more restricted sense, sometimes called experimental science.