We have peered far into the Universe and vastly expanded our knowledge of distant realms. But interestingly enough, we are still refining our understanding of our own place within our galaxy, the Milky Way. Research into this question follows in the footsteps of many great names in astronomy: from Herschel to Hubble, and from Kapteyn to Kant, generations of astronomers helped to establish our understanding of our place in space.

Imagine, if you will, trying to take a picture of the United States from somewhere close to the center of it. (That’s right. Lots of corn fields.) You would have no way to observe the entire country at the same time. Astronomers face a similar challenge in observing our home galaxy: we live within the disc of the Milky Way, a long way from the center (about 7,600 parsecs or 25,000 light years) and only a small distance from the middle of the plane (27 parsecs or close to 88 light years), with thick lanes of gas and dust blocking our view. We can see other more distant galaxies and have discovered many shapes and types, so comparing ourselves to them can help us determine the approximate shape and layout of the Milky Way.

Dr. Alyssa Goodman and her team recently realized that a dark cool cloud dubbed “Nessie” in the constellation Ara might have some secrets to tell about the Milky Way. We have seen similar features in other spiral galaxies: slightly denser tubes of material that define long spiral arms. By studying this “bone” of our galaxy, we may soon be able to refine our map of home to an even greater degree. We reside just far enough from the plane of the Milky Way’s disc that we could perhaps one day find the rest of these bones and create an even better layout of our place in space.

This concept and more appear in Goodman’s Authorea paper, currently in development now for later publication. Amazingly, you can to read the paper online while the authors finalize it! Talk about science in action…

Josh Roberts is a program presenter and astronomer at the California Academy of Sciences. He also contributes content to Morrison Planetarium productions.

Image: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

Earth’s neighborhood just got a little larger.

Astronomers thought that Earth was located on a spur of an arm of the Milky Way… until data from the Very Long Baseline Array telescopes suggested that we could be located closer to the center.

While it’s simple to observe a bird’s-eye view of other galaxies, models of the Milky Way are inaccurate due to Earth’s limited vantage point. We are attempting to measure an entire galaxy using only Earth’s narrow perspective, and at the center of our galaxy is a large bulge, blocking about half of the Milky Way from view.

To make the best model possible, astronomers use a technique called parallax. Measurements are taken from locations on either side of the sun to give multiple perspectives of our location in the sky. Then, astronomers use trigonometry to calculate where we might reside in comparison to distant objects.

At the center of the Milky Way is a supermassive black hole, whose gravitational pull is capable of keeping 200–400 billion stars in orbit around the galaxy. Measurements from NASA’s Spitzer Space Telescope revealed that these stars are oriented in two arms that spiral around the black hole.

“Based on both the distances and the space motions we measured, our Local Arm is not a spur,” said Alberto Sanna, a postdoctoral fellow with the Max-Planck Institute for Radio Astronomy (MPIFR). “It is a major structure, maybe a branch of the Perseus Arm, or possibly an independent arm segment.”

Sanna and his colleagues presented their research this week at the American Astronomical Society meeting, held in Indiana.

Astronomers are creating increasingly accurate models of the Milky Way and every new finding tells us more about the entire universe.

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA

The galaxy, dubbed with the melodic name MACS 1149-JD, was spotted using  the combined power of NASA’s Spitzer and Hubble space telescopes as well as the phenomenon of gravitational lensing – using the gravity of nearer massive galaxies to bend and magnify the light of more distant ones behind them, which would otherwise remain invisible.

Small and compact, the galaxy appears to contain the equivalent of only about 1 percent of the Milky Way’s mass. The galaxy is quite young, only about 200 million years old, but we see it far back in time, when the Universe was quite young. (Imagine looking at an old photograph of your great grandparents: an old image showing a perhaps quite young couple.)  Light from the young galaxy captured by the orbiting observatories shone forth when the 13.7-billion-year-old Universe was just 500 million years old.

MACS 1149-JD existed during an important era when the Universe began to emerge from the cosmic Dark Ages. During this period, the Universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens up a window into the deepest, remotest periods of cosmic history.

“This galaxy is the most distant object we have ever observed with high confidence,” says Wei Zheng, lead researcher on a paper appearing in Nature this week. “Future work involving this galaxy—as well as others like it that we hope to find—will allow us to study the universe’s earliest objects and how the Dark Ages ended.”

According to leading cosmological theories, the first galaxies should have started out tiny like MACS 1149-JD. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

These first galaxies likely played the dominant role in the “epoch of reionization,” the event that signaled the demise of the universe’s dark ages. This epoch began about 400,000 years after the Big Bang when neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the Universe to ionize, or lose an electron, a state that the gas has remained in since that time.

Astronomers plan to study the rise of the first stars and galaxies and the epoch of reionization with the successor to both Hubble and Spitzer, NASA’s James Webb Telescope, which is scheduled for launch in 2018. The newly described distant galaxy likely will be a prime target.

Image: NASA/ESA/STScI/JHU

UC Santa Cruz researchers, using Hubble’s powerful Wide Field Planetary Camera 3, have looked 13.2 billion years into the past, discovering a small, compact galaxy of blue stars that existed only 480 million years after the Big Bang.

Creatively named UDFj-39546284, it ranks as the most distant galaxy yet observed. And it is pretty small by galaxy standards—over one hundred such mini-galaxies would fit inside our Milky Way.

Although individual stars can’t be resolved by Hubble, evidence suggests that this is a compact galaxy of hot stars that first started to form 100 to 200 million years earlier in a pocket of dark matter.

How do scientists find these distant, infant galaxies? According to Universe Today,

Astronomers gauge the distance of an object from its redshift, a measure of how much the expansion of space has stretched the light from an object to longer (“redder”) wavelengths.

Nature published the paper describing UDFj-39546284 last week. But astronomers calculate a 20% chance that the distant light is not a galaxy. It will take the pricey James Webb Telescope to confirm its galactic standing. Webb’s infrared vision should provide spectroscopic measurements that can confirm the tremendous distance of the reported object. For now, UDFj-39546284 will have to wait—the telescope won’t launch for at least another three years. But heck, what’s three years compared to 13.2 billion?

Image credit: NASA, ESA, G. Illingworth (University of California, Santa Cruz), R. Bouwens (University of California, Santa Cruz, and Leiden University), and the HUDF09 Team