When I was young, my parents had a copy of the National
Geographic Atlas—the one that weighs around 30 pounds.
While the maps of Earth were fascinating, what held my attention were
the pictures of the heavens.
Starting with the solar system, then the constellations, then our galactic
neighbors, and finally a depiction of the known universe at the
time, the Atlas was fascinating.
On Friday, Google—after showing
everyone what the Earth,
our moon, and Mars looks
like—turned its attention to Google Sky. While previously available as an addition to Google Earth, this new version is accessible through a web browser and makes sharing images as easy as sharing a hyperlink to a web page. In what follows, we briefly review Google Sky while pointing out some of the most interesting and impressive destinations to be found... in outer space.
Hands on with Google Sky
At first glance, Google Sky has an interface—and response
speed—very similar to that of Google Maps. There's the familiar zoom level bar on the left, and one can scan via a set
of buttons or by dragging the mouse around the screen.
I spent some time exploring the universe from my sofa, which is what Google Sky is all about. To help you understand where you are and how to get where you might like to go, the Google Sky screen displays the right ascension (RA) and
declination (DEC) of where your pointer is at all times (RA and DEC are coordinates in the equatorial
coordinate system that astronomers use to pinpoint astronomical bodies). Along with simply being able to view our Universe, Google has added a trio of interesting overlays, each with user controllable
transparency. Understanding these is key to getting the most out of Google Sky.
For scientific inquiry, one can overlay the cosmic
microwave background (CMB) radiation or the infrared (IR) signature of the universe on top of the visual sky that you are looking at; unfortunately this only worked at zoom levels
above a certain point—often too big to see any of the features of
individual bodies. I imagine this is not a shortcoming of Google's code, but
a lack of detailed survey data. The length scale of a single
astronomical body (galaxy, supernova, etc.) compared to the entire
universe is just too disparate.
Searching the heavens
Google naturally provides a search feature so
you can find your favorite heavenly body by name or description. I began my investigation by searching for some recent newsworthy astronomical events. Sadly this is where the wheels start to come
loose. Going back over a sampling of recent Nobel Intent
stories on dark
matter, a
"death star," a supernovae
of unprecedented size, and random
X-ray surprises, I didn't find any relevant materials. These objects were apparently all too obscure, which suggests that Google has much more work to do in mapping astral phenomena to the news.
Still, there's plenty to check out. Google Sky
has a collection of pre-selected heavenly bodies for people to look
at. Starting with our Solar System, it had images of all the
eight planets plus Pluto, although no mention of Ceres or Eris. Next up in the pre-selectable
feature set were the constellations. Selecting this not only allowed
one to see a given constellation, but it connected the dots—literally—between the various stars that each constellation is composed from. This feature combined
with the historical overlay is very interesting.
After the constellations, Google Sky has a large collection that it
calls the "Hubble Showcase," referring to images captured
over the past few decades by the Hubble
Space Telescope. The images here are quite beautiful, but are
nothing new. Honestly I can find better images of each by, perhaps
ironically, doing a simple Google image search for them. When viewed in
Google Sky, you essentially see a high
resolution image of the selected body or phenomenon pasted
onto the low resolution surrounding star field. Each has a
pop up box with information and a link to learn more about the
image or object. After the Hubble collection, there is a category for
what they term "Backyard Astronomy," which is really a collection
of images of approximately 100 different galaxies.
Seeing the invisible
Up to this point, all the images shown have had one thing in common:
they are in the visible light spectrum. Visible light only shows us a small
picture of the entire universe; non-visible spectra such as
ultraviolet (UV), infrared and X-ray hold a whole other world of information.
Here is where Google Sky becomes very cool. There are three more
sections that highlight fantastic images from the Chandra X-Ray Observatory,
the GALEX
Evolution Explorer (UV), and the Spitzer Space
Telescope (IR). What makes these very cool is that under
each selected body there is a slider that will change the displayed
image back and forth between the visible and invisible spectrum.
For instance, if one looks at Cassiopeia A as it would be seen in
the visible
spectrum, you would see a small amount of hot gas. However, if
you look at its X-ray
spectrum, far more information can be gleaned—in fact
the X-rays observed from this supernova remnant offered
up clues as to the origin of high energy cosmic rays.
Similarly interesting things can be seen using IR and UV—in the
visible spectrum, very little of interest can be seen, but outside what
humans can see without the aid of technology lies a plethora of
interesting dynamics. However, it must be pointed out that the zooming
functionality doesn't work so well when moving between two different
spectra. If one image is not sized similarly to the other, the function
ceases to work, and you will only see one spectrum regardless of what
you do with the slider.
The Top 10
The following is a list of 10 of the best images I found while using Google Sky. This is not meant to be an objective list, but I would argue that these are all places not to be missed if and when people visit the Universe:
- If you ever want to see the beginning of a galactic
collision, be sure to visit the outskirts of NGC2207. - While most likely seen before, The
Pillars of Creation in the Eagle Nebula are one of Hubble's
crown jewels—be sure to look at their X-ray spectrum as well for
hidden clues as to new stars forming. - For more galactic collision action, see the Mice
galaxies, NGC 4676. - For further proof that Einstein was right, have a look at
an extreme example of gravitational
lensing. - For things that go (or went) boom, have a look at Chandra's
images of Kepler's
Supernova Remnant, and the remnant of supernova G292.0+1.8.
Note that both are basically invisible in the visible spectrum. - Since the majority of our readers reside in the northern hemisphere, I suggest having a look at something you will never see here in the night sky: the Southern Pinwheel Galaxy is quite a sight.
- While the CMB represents the earliest views we have of the universe, it is worthwhile to check out the galaxies furthest from us, taken courtesy of Hubble's Deep Field imager.
- Finally, check out a pair of nebula, the Crab
and Rosette,
that show their colors in the infrared spectrum courtesy of Sptizer.
In the end, Google Sky is a fun and educational tool. The ability to view astronomical bodies in various
spectra is by far the coolest feature, and I encourage
readers to check it out.
Going into this, I had hoped for a
free-wheeling romp around the universe; what I got was a guided tour at
the local science museum. While not bad, it fell short of my hopes. I do encourage fans of astronomy to look into it, if only
to perhaps discover something new on the 'pre-selected' menus. Just keep in mind that for
just about every highlighted body, I was able to find better images
faster elsewhere on the web.
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