The Ultimate Reason Why Astronomy is Essential

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The Ultimate Reason Why Astronomy is Essential

David J. Eicher, editor in chief of Astronomy Magazine, gave an interesting talk at this year's Northeast Astronomy Forum entitled "Does the Universe Really Care About Itself?" I want to share one theme of Dave's lecture that I believe everyone needs to know and consider. Sit down, I'm about to be Mr. Doom and Gloom.

You may have heard that our Sun has about 5 billion years of life left in it. No worries, you think, that's a long way off...right? But, did you know that long before the Sun meets its eventual demise, it will swell to the point where it'll boil off the Earth's oceans? That will happen in a mere 800 million to 1 billion years from now. Still far into the future, huh? Well, it gets worse. We don't even have that much time left to live on this world (told you I was going to be gloomy).

Every 100 million years or so, a 10-kilometer size object strikes the Earth causing a global extinction. Meaning from a statistical probability standpoint, the planet will see eight to ten such events BEFORE the oceans go bye-bye. The last one happened about 66 million years ago and killed all the dinosaurs...remember that one? Luckily some little rodent-like mammals, and all the cockroaches, managed to survive and along we came. But...it gets worse.

Every 500,000 years or so, a 2-kilometer wide rock hits us. When this happens next, it will make a crater nearly 30 miles wide and will cause everything within 150 miles to instantly burst into flames. Everything within about 400 miles will also probably catch fire from all of the ejected debris re-entering the atmosphere. The ozone layer of the atmosphere (you know, the layer that keeps all that cancer-causing UV radiation from reaching our bodies) will disappear for years. There will be global crop failures and some extinctions. Oh, and summer vacations will be canceled that year.

But...it gets even worse. About every 200,000 years, a 1-kilometer wide rock will take a shot at this blue marble. While the effects from an object of this size are less than the larger impacts, you still don't want to be within 200 miles of it unless you have a really super-duper big bag of marshmallows to roast.

I am writing this because I don't think most people realize the extent of the cosmic shooting gallery we live in. THIS is the main reason why astronomy and space exploration are so critical to humankind. Sure, it won't cure hunger or produce a vaccination against HIV but that's not what astronomy and space exploration are trying to do. Harsh truth coming up -- if we intend to continue on as a species we are going to have to leave this rock someday. I realize the sense of urgency may not rank right up there with global warming, but it should. We can see global warming happening, we may not see the threat from above until it is too late. And, at this point in our evolution, there is absolutely nothing we can do about it. But, we CAN change that if we want to.

Now that you know the reality of our situation, get ready to participate in AsteroidDay on June 30th, 2015. http://www.asteroidday.org/

‪#‎AsteroidDay‬

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ALMA is Just Getting Warmed Up

ALMA's image of the HL Tauri disc has been big news in astronomy.  But let's take a step back and look at HL Tauri's interesting neighbor, XZ Tauri.  The Hubble Space Telescope got into the act yesterday by releasing this new image of Taurus with both XZ and HL Tauri visible.  In the Hubble image, XZ Tauri is the bright star surrounded by reddish colored gas and HL Tauri is the blue "cloud" next to it.  The actual star and disc captured in the ALMA image is embedded in the gas so all we see is a brightly glowing cloud.  

There are many other interesting objects in this image including Harbig Haro (HH) objects, which are areas of nebulosity associated with jets from young stars. V1213 Tauri (lower right) is another star shrouded in dust with jets emanating from its poles that are colliding with the interstellar medium.

But back to XZ Tauri.  It was once thought to be a binary system, however, one of the stars is now believed to be a binary as well, making it a triple star system.  There is also evidence that suggests there is a protostellar disc.  In reviewing the observing proposals for ALMA, there is a high-priority proposal from 2011 that aims to use ALMA's resolving power to investigate binary star systems in Taurus.  I suspect that in the future, we're going to get a first glimpse of how a multiple star system looks and what the planet forming disc looks like in such an interesting place.  Don't expect Tatooine to be found there though (it is in a binary star system).

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A Perfect Example of Why Aperture is Important

The major astronomy news from today has to be the amazing image of the disc surrounding HL Tau taken by the Atacama Large Millimeter/submillimeter Array (ALMA).  This budding solar system lies approximately 450 light-years from Earth in the constellation Taurus.  

Up until today, the best image I have seen of a protoplanetary disc, that wasn't an "artist's rendition", is the image of the nearly face-on disc of TW Hydrae captured by the Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer (NICMOS).  The Hubble image, while impressive, lacks the resolution and subtle details apparent in the ALMA image.  Keep in mind, the Hubble image is made from light in the near-infrared wavelength captured with an optical telescope.  ALMA "sees" radiation at wavelengths of a few hundred micrometers to about 1 millimeter, which is near the boundary on the electromagnetic spectrum between infrared and radio waves.  But, instead of using glass and mirrors to capture and focus light, ALMA uses antennas that look like big satellite dishes.  And, here's where ALMA gets really interesting, the antennas are somewhat portable and reconfigurable.  For imaging HL Tau, individual 12-meter antennas were precisely arranged and pointed to create a single dish 15 kilometers across.  Even though Hubble is above the Earth's atmosphere, it's 2.4 meter aperture can't compete with the resolving power of an imaging system that is 15 kilometers across!  

"Aperture fever" is the notion that all amateur astronomers eventually reach a mental state where we are convinced that we must have a bigger piece of glass or a larger mirror.  Why?  Because the larger the aperture, the more light is collected by the instrument leading to better views through an eyepiece or more photons hitting a CCD.  The professionals know this as well.  It is why we see larger and larger optical instruments being proposed and built.  The first of these next generation super Earth-based telescopes to come online will be the Thirty Meter Telescope (TMT) on the summit of Mauna Kea in Hawaii.  It will have a mirror made up of 492 hexagonal segments that spans 30 meters.  This will give it the ability to collect more than 10 times the light of one of the 10 meter Keck telescopes, also on Mauna Kea's summit.  It will have 144 times the light gathering power and 10 times the spatial resolution of the Hubble Space Telescope.  The TMT won't hold the aperture crown for long however, the European Extremely Large Telescope (E-ELT) will be hot on its heels with a 39 meter instrument located at Cerro Armazones in the Atacama Desert of northern Chile.

Seeing this incredible planet-forming disc around HL Tau and comparing it to the earlier attempts made by smaller aperture instruments truly does highlight the value of larger apertures.  It's clear to me that the big boys all have aperture fever and someday you may too...don't say I didn't warn you!

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