“1.) Galaxy pair AM 2026-424. With two massive galaxies colliding head-on, an intermediate ring of blue stars appears before the inevitable final merger.”
In 1990, the Hubble Space Telescope was launched, providing humanity with unprecedented views of the Universe. Each and every year, with 2019 marking the 30th consecutive year, a series of images get produced that shed light on some aspect of our Universe in unprecedented fashion. Despite Hubble’s big gyroscope failure (and scare) at the end of last year, 2019 has turned out to be no exception, with 10 spectacular new images and 7 almost-as-spectacular honorable mentions.
Your 2019 Holiday Gift Guide For Space, Astronomy, And Science Lovers
“At The Edge Of Time, by Dan Hooper. This new book, out just a few weeks ago, is my favorite new science book of 2019. As a theoretical cosmologist, Dan is all the things I appreciate in a scientist who writes about his own research: he’s knowledgeable, comprehensive, and careful to get the details right. He has clear opinions and preferences, but is willing and able to push them aside in service of teaching the reader about the strengths and weaknesses of a variety of perspectives on a myriad of issues at the frontiers of physics.
If you’re mystified and curious about the mysteries of the Universe, including dark matter, dark energy, and cosmic inflation, and want a unique take on all of these puzzles with a peek behind how science-in-action works, you won’t want to miss this book. (I liked it so much that Dan is going to be my next upcoming guest on the Starts With A Bang podcast!)”
Do you love space, science, astronomy, physics, the Moon, and learning about the frontiers of what we know? Well, the holidays are coming up (today is Black Friday), and if that describes you or someone close to you in your life, here is a complete gift guide for the science enthusiast in your life.
This One Distant, Red, Gas-Free Galaxy Defies Astronomers’ Expectations
“When two similarly-sized galaxies merge, it triggers a starburst: a massive formation of new stars. Under the right circumstances, some gas will form stars while the remainder is expelled, lost forever to the intergalactic medium. Once the gas for forming new stars is used up, the galaxy simply ages as the bluest, most massive stars die off. Over billions of years, only the redder, dimmer, lower mass stars remain.”
In astronomy, young galaxies actively form stars, and glow bright blue through the process. Only after many billions of years and at least one cataclysmic event do galaxies settle down into a gas-free, red state, once all the bluer stars have died out. “Red and dead” galaxies appear in the late Universe, normally as giant elliptical galaxies that lost their gas aeons ago.
Which is why this one galaxy is so puzzling: it’s red, dead, massive and compact, but it’s also sending us its light from 10.8 billion years ago!
LIGO’s Lasers Can See Gravitational Waves, Even Though The Waves Stretch The Light Itself
“But this is where the puzzle comes in: if space itself is what’s expanding or compressing, then shouldn’t the light moving through the detectors be expanding or compressing too? And if that’s the case, shouldn’t the light travel the same number of wavelengths through the detector as it would have if the gravitational wave had never existed?
This seems like a real problem. Light is a wave, and what defines any individual photon is its frequency, which in turn defines both its wavelength (in a vacuum) and its energy. Light redshifts or blueshifts as the space it’s occupying stretches (for red) or contracts (for blue), but once the wave has finished passing through, the light returns to the same wavelength it was back when space was restored to its original state.
It seems as though light should produce the same interference pattern, regardless of gravitational waves.”
Have you ever thought about how gravitational wave detectors work? By passing light down two mutually perpendicular arms, reflecting them back and reconstructing an interference pattern, we can detect a passing wave by how it changes the arm-lengths of the light. But the light itself also gets compressed and expanded, and shouldn’t those effects cancel out?
“The fact that saves us, which Olbers had no way of knowing back in his day, is not that the Universe isn’t infinite in extent (it still could be), but that it doesn’t go back, in its current form, for an infinite amount of time. The Universe we inhabit today had a beginning: a day without a yesterday. That beginning is known as the Big Bang, which puts a starting line for all the matter, radiation, energy, and light that possibly exists in the observable Universe.
The Universe hasn’t been around forever, and therefore we can only observe stars and galaxies that are a specific and finite distance away. Therefore, we can only receive a finite amount of light, heat, and energy from them, and there cannot be an arbitrarily large amount of light in our night sky.”
Ask a child what the color of the night sky is, and you’ll uniformly get the same answer: black. The night sky is one of the darkest things we have to look at in all of nature. And yet, the fact that the sky is completely dark at night is a bit of a paradox. If the Universe is full of light sources like stars and galaxies, and it’s truly infinite in extent, then no matter how far away you had to look to see it, eventually every line-of-sight you could imagine would end on a light source. Everywhere, in all directions, all you’d see was a bright light.
The Perseid Meteor Shower Is Here, And Might Foretell Humanity’s Extinction
“The Perseid meteor shower, even with a near-full Moon to contend with, should be one of the year’s most spectacular meteor showers. When you look up, scope out the northwest skies after sunset (from the northern hemisphere) and look for fast-moving streaks radiating away from near the “W” in Cassiopeia. A few dozen bright streaks per hour, even in the worst-case scenario, should still await you.
But as you watch the skies, keep in mind that there’s an enormous comet responsible for this light show, and it returns every 133 years. In just a handful of orbits, it will come closer to Earth than any reasonable person should be comfortable with. Even if it’s not Swift-Tuttle, it’s only a matter of time before an object just like it comes for us, threatening the extinction of humanity and much more. We have a choice: we can let it come, or we can be ready. Extinction by comet strike is, for the first time ever, no longer an inevitability. We just have to invest in our own cosmic safety to avoid this catastrophic fate.”
When a meteor shower comes our way, you likely look up at the sky and marvel. After all, why wouldn’t you? It’s one of the night sky’s most beautiful and natural sights. In the case of the Perseids, whose peak is just around the corner, it’s the most spectacular show of the year. Even when there’s a near-full Moon to contend with, like this year, it’s still worth taking a look at one of nature’s most wondrous occurrences.
Starts With A Bang Podcast #47 – Ice Giants At The Solar System’s Edge
What do we really know, and what mysteries are left to solve, about the outer worlds of our Solar System, and about the gas giant and ice giant worlds found throughout the Universe? Remarkably, if you had asked this same question 30 years ago, we would have had a quaint story about how planets form and why our Solar System has the planets it does, and we assumed that these rules would be extended to all solar systems in the galaxy and Universe. But with the deluge of exoplanet data, accompanied by better observations and simulations of our Solar System, that old story isn’t even the half of it.