Like the drift of the continents or the erosion of great mountain ranges on Earth, the motion of the stars across the sky is almost imperceptibly small over the paltry span of a human lifetime. But in this quite astonishing video made with data from the European Space Agency’s (ESA’s) Gaia spacecraft, which compresses 5 million years of star motion into a few minutes, you can see more than 2 million stars move across the sky like grains of pollen floating in a breeze. It is mesmerizing (and unexpectedly calming) [Read more…] about Moving StarsShare This:
Science of Astronomy
Articles about the science of astronomy and objects that are visible in the night sky.
In the early 1930′s, Bell Labs, the research division of AT&T, launched a project to use radio “short waves” to transmit telephone calls across the Atlantic. The technology to transmit signals via short waves was reasonably well understood. But engineers also needed to understand sources of noise that might interfere with radio communications signals. So the powers-that-were at Bell Labs tasked a young engineer to find sources of radio static that might interfere with transmissions. During his work, this young engineer, Karl Jansky, made an accidental discovery that revolutionized astronomy [Read more…] about The Mysterious Hiss from the Milky WayShare This:
In our previous stop on our tour of celestial objects of cosmological importance, we looked at a handful of galaxies measured by the early 20th-century astronomer Vesto Slipher. The former Indiana farm boy wrestled with a modestly endowed telescope and a 450-pound spectrometer to make an astonishing discovery. He found the ‘spiral nebulae’ like Andromeda (M31) and the Sombrero (M104) were moving away from us at astonishing speeds, up to 1000 km/s and far faster than any nearby stars. The speeds of these spiral assemblies strongly suggested they lay outside our own group of stars, and were perhaps separate galaxies in their own right far outside our own.
But in science, a strong suggestion is not proof.
In the first years of the 20th century, astronomers had no way of knowing for sure the distance to these spiral assemblies. Indeed, a hundred years ago, they only could estimate the distances to a handful of nearby stars. The true scale of even our own galaxy was a complete mystery. No one knew whether the Milky Way was all there was to the universe, and whether it was a hundred light years across, or a thousand, or a trillion. Never mind the distances to the mysterious ‘spiral nebulae’, which may simply have been nearby star systems in the process of formation.
The key to the distance to the spiral nebulae, which we now know to be separate galaxies, and to the universe itself, lay unexpectedly in a class of unassuming stars, many of which you can see from your backyard with a pair of binoculars or without any optics at all [Read more…] about The Distances to the GalaxiesShare This:
A few weeks ago you had a look at the justly famous Sombrero Galaxy in the constellation Virgo. In a small telescope, the galaxy looks like a silver shard, a faint sliver of light with a star-like core obscured from end to end by a sharply defined lane of dust. It’s one of the prettiest galaxies in the night sky, and it was also a favorite of the Indiana-born astronomer Vesto Slipher, who paused to admire it from time to time as he analyzed its light to make one of the great discoveries of the 20th century. Let’s examine a few more photogenic galaxies on Slipher’s observing list from more than a century ago, and understand just what it was that he unexpectedly discovered [Read more…] about Spring Spiral Galaxies and the Expanding UniverseShare This:
If you’ve been following the news this week, you know that Jupiter has a new moon, a man-made moon called Juno. The NASA spacecraft, bejeweled with solar cells and as big as a basketball court, entered an elongated orbit around the big planet on July 4 as it began a 20-month study of the structure of Jupiter. While Jupiter may be fading in the western sky after sunset, still visible but soon to be lost to our telescopes, it will continue to reveal many secrets to Juno during the coming months [Read more…] about Farewell to Jupiter, and HelloShare This: