astronomy

The North Star, the Pole Star, the Guiding Star, Polaris: Its many names reflect the many centuries humans have gazed northward to it for guidance. Because Earth’s North Pole is aligned with Polaris’ position in the sky, the star appears motionless, providing a steadfast beacon for early sailors and adventurers alike. But the star itself is far from motionless. In fact, Polaris is a specific type of star known as a Cepheid variable, which pulsates, varying in size and luminosity over a period of days and, according to recent observations, also ejects large amounts of mass into space.

Astronomer Adam Riess and his team made a huge splash in 1998 when they announced the finding of dark energy. That work also included the discovery that the universe is expanding at an increasing rate. Riess and his colleagues were awarded the Nobel Prize in physics for their discovery.

Blogging on EARTH

In need of a sense of perspective? The European Southern Observatory has a new way to look at the universe: with a zoom button.

Fifty light-years from Earth, in the constellation Pegasus, burns a yellow star not unlike our sun. The star, called 51 Pegasi, was one of 142 stars under the watchful gaze of Swiss astronomers Michel Mayor and Didier Queloz of the University of Geneva in 1994. From the La Silla Observatory at the southern end of Chile’s vast Atacama Desert, Mayor and Queloz were tracking how these stars move in the sky, hoping to determine whether the stars were alone — or whether any of them might be accompanied by a planet or two.

May 29, 1919

On May 29, 1919, the moon’s silhouette crept slowly over the sun, bringing premature night to observers in a broad swath of the Southern Hemisphere between South America and Africa. Few onlookers realized that this event would provide the first successful test of Albert Einstein’s theory of relativity.