At The Center of Everything

Vega, the fifth-brightest nighttime star, beams almost straight overhead early this month and may be the most important luminary in the sky after the Sun. But how exactly do you say its name? Is it VEE-guh or VAY-guh?

In July 2006, Sky & Telescope's Tony Flanders addressed the question:

"In 1941 the American Astronomical Society (AAS) formed a committee of Samuel G. Barton, George A. Davis, Jr., and Daniel J. McHugh to consult with astronomers, educators, Arabic scholars, and planetarium lecturers and come up with a list of preferred pronunciations for common star names and constellations. 

Their final report, adopted by the AAS, appeared in Sky & Telescope for June 1943, page 12." They decided that Vega should be pronounced VEE-guh. This made sense because for centuries it had been known as Wega and spoken as WE-guh, which means descending eagle in Arabic. 

Later, the W evolved into a V, but the pronunciation remained the same: VEE-guh. As a budding amateur astronomer in 1966, I owned an Edmund planisphere that included an instruction manual with a pronunciation guide in line with AAS standards.

Yet somewhere along the way Vega became (mostly) VAY-guh, leaving me and my ilk in the minority. Nowadays, the online Merriam-Webster dictionary gives both pronunciations, while the American Heritage Dictionary lists VEE-guh. Recognizing that language evolves, I tell newcomers to the hobby that either is correct.  READ MORE...

Webb Telescope Shatters Records

The very first results from the James Webb Space Telescope seem to indicate that massive, luminous galaxies had already formed within the first 250 million years after the Big Bang. If confirmed, this would seriously challenge current cosmological thinking. For now, however, that’s still a big “if.”

Shortly after NASA published Webb’s first batch of scientific data, the astronomical preprint server arXiv was flooded with papers claiming the detection of galaxies that are so remote that their light took some 13.5 billion years to reach us. Many of these appear to be more massive than the standard cosmological model that describes the universe’s composition and evolution.

“It worries me slightly that we find these monsters in the first few images,” says cosmologist Richard Ellis (University College London).

Young, massive stars in newborn galaxies emit vast amounts of energetic ultraviolet radiation. As this light moves through expanding space for billions of years, the wavelengths stretch (redshift) all the way into the infrared – radiation that Webb’s instruments are sensitive to.

It takes careful spectroscopic measurements – either by Webb’s spectrometers or by the ground-based ALMA observatory that operates at even longer wavelengths – to precisely determine the redshifts, which tells you how far out into space — and thus how far back in time — you’re looking. But there’s a quick (albeit less reliable) workaround that gives a rough idea.

Neutral hydrogen atoms in intergalactic space absorb ultraviolet radiation at wavelengths shorter than 91.2 nanometers. For remote objects, this threshold also redshifts to longer wavelengths, into the infrared for the most distant galaxies. 

Since Webb’s near-infrared camera NIRCam takes measurements through a large number of filters, each covering a different wavelength band, a galaxy may be visible in some channels but not in others. The wavelength band in which the galaxy disappears roughly indicates its redshift, and the corresponding look-back time.  READ MORE...