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Science of Astronomy

Articles about the science of astronomy and objects that are visible in the night sky.

The Distances to the Galaxies

July 10, 2017 by Brian Ventrudo Filed Under: Science

Multiple images by NASA’s Hubble Space Telescope of the Cepheid variable star that in 1923 altered the course of modern astronomy. Called “V1″, it was first detected by Edwin Hubble with the 100” reflector at Mt. Wilson Observatory. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

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 Galaxies

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Filed Under: Science cepheids, galaxies, science

Spring Spiral Galaxies and the Expanding Universe

June 16, 2017 by Brian Ventrudo Filed Under: Science

The Andromeda Galaxy, the nearest major spiral galaxy. Image by Terry Hancock at Downunder Observatory and Grand Mesa Observatory.

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 Universe

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Filed Under: Science galaxies, science, vesto slipher

Farewell to Jupiter, and Hello

July 8, 2016 by Brian Ventrudo Filed Under: Science

Artist's concept of Juno at Jupiter (credit: NASA)
Artist’s concept of Juno at Jupiter (credit: NASA)

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 Hello

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Filed Under: Science juno, jupiter, solar eclipse

The Dusty Birth of a New Star

February 10, 2016 by Brian Ventrudo Filed Under: Science

A newly formed star lights up the surrounding cosmic clouds in this image from ESO’s La Silla Observatory in Chile. Dust particles in the vast clouds that surround the star HD 97300 diffuse its light, like a car headlight in enveloping fog, and create the reflection nebula IC 2631. Although HD 97300 is in the spotlight for now, the very dust that makes it so hard to miss heralds the birth of additional, potentially scene-stealing, future stars. Credit: ESO.
A newly formed star lights up the surrounding cosmic clouds in this image from ESO’s La Silla Observatory in Chile. Dust particles in the vast clouds that surround the star HD 97300 diffuse its light, like a car headlight in enveloping fog, and create the reflection nebula IC 2631. Although HD 97300 is in the spotlight for now, the very dust that makes it so hard to miss heralds the birth of additional, potentially scene-stealing, future stars. Credit: ESO.

This marvelous image from the European Southern Observatory shows a small section of the Milky Way going about its business making new stars. Here you see in this dusty region the reflected light of a new main sequence star, HD 97300, as it settles down into its billion-year life span [Read more…] about The Dusty Birth of a New Star

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Filed Under: Science eso, nebula, new star

A Ninth Planet Discovered?

January 21, 2016 by Brian Ventrudo Filed Under: Science, Solar System

Artist's conception of the hypothetical "Planet 9" in the distant regions of the solar system. Credit: Caltech/R. Hurt (IPAC)
Artist’s conception of the hypothetical “Planet 9” in the distant regions of the solar system. Credit: Caltech/R. Hurt (IPAC)

It’s been 170 years since the eighth (and so far last) major planet, Neptune, was discovered in our solar system. Pluto, of course, was discovered in 1930, heralded as the ninth planet, but then demoted by consensus of the astronomical community, largely at the behest of the Caltech astronomer Mike Brown who reasoned that Pluto was not large enough to gravitationally clear its path of other bodies, one of the three criteria for a major planet. In the ten years since Pluto’s demotion, Brown has been asked if there are any other planets in our solar system. His answer: “Nope, that’s it.” [Read more…] about A Ninth Planet Discovered?

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Filed Under: Science, Solar System ninth planet, solar system

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