What Would The Milky Way Look Like If You Could See All Of Its Light?
“When you look at the Milky Way in visible light, you might see billions of stars, but you miss so much more. The human eye is only sensitive to a tiny fraction of the entire electromagnetic (light) spectrum. Each wavelength range showcases a novel view of all that’s out there.”
If you looked out at our galaxy with your eyes and the wavelengths they’re sensitive to alone, there’s an incredible amount of information you’d miss no matter how powerful you became at gathering light or resolving individual objects. That’s because visible light only occupies a narrow range of electromagnetic wavelengths, meaning that what you can see is limited to what emits visible light (stars and some reflective clouds) and constrained by dust, which can absorb all the visible light behind it.
“For almost every conceivable application to astronomy, going to the Moon is a vastly inferior location than simply being above the Earth’s atmosphere. The temperature extremes experienced everywhere on the Moon are an extraordinary challenge over and above any benefit you get from being on the Moon’s surface. Only in radio frequencies do the benefits of being on the lunar far side offer an opportunity for observing that we cannot get from either terrestrial or space-based observing.
Until the cost is either brought down or something we demonstrate we’re willing to pay, though, it is unlikely we’ll ever see a lunar telescope that’s superior to the other options. The Universe is out there, waiting for us to discover its secrets. When we decide a lunar radio array is worth it, we’ll advance tremendously in uncovering our cosmic origins.”
Practically everyone knows that our opportunities to view the Universe and learn about it, astronomically, are limited here on Earth. The atmosphere interferes with our ability to observe what’s out there, as do weather, human-created signals, and many other issues. We could go to space, of course, but many problems persist there as well. Perhaps putting a telescope on the far side of the Moon would hold the answer? As it turns out, the Moon is an even harsher environment, in many ways, than the depths of interplanetary space. There’s only one specific application that we know of, for radio astronomy, that offers a tremendous advantage. When we’re ready to invest and build a lunar array of radio telescopes, though, we’ll learn more about the early Universe than we ever have before.
But how do we, sitting on earth know how rapidly a planet like Mercury which is around 48 million miles away is rotating ?
This is a very interesting example of Doppler effect.
Radio waves are shot from the earth towards the surface of mercury, one side of the planet will be red shifted (since it is moving away from you) and the other will be blue shifted (since it is moving towards you).
By measuring this apparent change in frequency, we can find out how rapidly mercury is rotating.
Using this method we have found out that the rotation period of mercury is approximately 58.6 days.
Mysterious Light Seen Around A Newly Forming Star; Here’s What Astronomers Think It Means
“In order to reproduce the signatures we see, the disk has to be practically edge-on to our line of sight. Which seems weird, because the main binary system that is CS Cha has a disk that’s inclined, somewhere between edge-on and face-on. This wouldn’t be the first time we’ve seen such a misalignment, as dusty, misaligned binary and trinary systems have been seen before. But it already marks the very first time we’ve detected a polarized companion outside of one of these protoplanetary disks! Because so much of the light is blocked by this dust disk, though, we have a hard time telling what the mass of this companion is. Is it a Jupiter-class planet? A super-Jupiter? Or, as the authors conjecture, is it a low-mass brown dwarf: a failed star?
With a dusty disk around the companion, there’s a near-certainty that whatever it is, it will be developing its own orbiting companions in the imminent future!”
600 light years away, in a small constellation in the southern skies, there’s a new binary star system that’s just in the process of forming: CS Cha. It’s only 2 or 3 million years old, a blip in a star’s lifetime. And all around it for billions of kilometers is a dusty, protoplanetary disk. But far outside that disk is a surprise: a companion object. Most companions will be either large planets or brown dwarfs, and that’s not a surprise. But when you look at the light, it should barely be polarized at all: 1% at most. Yet when we looked at the companion with SPHERE, a new instrument aboard the Very Large Telescope in Chile, we found that a whopping 14% of the light was polarized!
Five reasons why the signals from Stephen Hawking’s Breakthrough Initiative aren’t aliens
“In 2012, a series of nine bursts were observed by both the Very Large Array and Arecibo, four of which were seen simultaneously. For the first time, this allowed us to pinpoint the location of a FRB’s source: a dwarf galaxy 3 billion light years away. Last month’s reinvestigation discovered a series of 15 repeating FRBs from the same source, each lasting under 300 microseconds. Is it advanced, powerful aliens? There are five reasons why that’s likely untrue.”
Whenever we detect a signal that we can’t immediately explain, it’s a very human trait to ascribe our greatest hopes (or fears) to it. In the case of a peculiar radio signal originating from deep space, that means the wildest speculations will involve intelligent aliens. But as much as many of us would hope that such a thing would be true, the physical properties of these fast radio bursts, even though they’re repeating, tell us otherwise. With an estimated 10,000 of them occurring on a daily basis, and with power some 10^19 times as great as the strongest radio signal ever generated by humanity, and with known astrophysical sources that can naturally generate signals of this magnitude and frequency, it’s completely unreasonable to think this has anything to do with aliens. Still, the science alone is interesting enough to warrant not only investigation, but a remarkable sense of wonder.
The Future Of Astronomy: Thousands Of Radio Telescopes That Can See Beyond The Stars
“Radio astronomy has brought us pulsars, quasars, microquasars, and mysterious sources like Cygnus X-1, which turned out to be black holes. The entire Universe is out there, waiting for us to discover it. When SKA is completed, it will shed a light on the Universe beyond stars, galaxies, and even gravitational waves. It will show us the invisible Universe as it truly is.”
When we break out the big guns – space telescopes like Hubble or James Webb – we can see the Universe as it was billions of years ago, if we look for long enough. From the first moment that the Universe forms stars and galaxies, so long as that light has a path to our eyes, humanity can view it with the right equipment. This record-breaking approach has brought us in contact with galaxies from as early as when the Universe was just 400 million years old: 3% of its current age. Yet no matter how far back we go, we’ll never be able to see the era from before there were stars or galaxies at all using this approach. But a new, ambitious project just might. The Square Kilometer Array (SKA), set to begin construction next year, will map out the invisible hydrogen in the Universe, including during the epochs in where there are no stars at all.