On clear, dark nights around the 285 corridor, you can see the Milky Way rise above the horizon and span the sky. The Milky Way isn’t just a pretty band of stars, it’s a barred spiral galaxy that we reside within. The center of the galaxy is a rectangular bar with arms spiraling around it.

Our galaxy consists of 100 – 400 billion stars, dark dust clouds, and gaseous nebulae, within which new stars are born. The dust clouds and nebulae hide many stars within the Milky Way, making it hard to determine the total number of stars in our galaxy, hence the wide range in the above-mentioned estimate.

At the galactic center is a supermassive black hole, Sagittarius A* (pronounced, ‘Sagittarius A Star’). A black hole is an object that gravitationally collapsed upon itself, leaving a region of space whose gravity is so strong that not even light can escape from it. A supermassive black hole is, well, supermassive! It’s a black hole millions, possibly billions of times the mass of the Sun.  Most large galaxies have supermassive black holes at their galactic centers.

It’s difficult to visualize the spiral nature of our galaxy since we reside within it. The Sun we orbit is an average star, located far from the center of the galaxy. By observing the Milky Way from our vantage point, it’s obvious that our galaxy is relatively flat, with a bulging center.

If we were able to observe the Milky Way Galaxy from ‘overhead,’ we’d see a minor ‘arm’ coming off of each end of the central bar. One of these minor arms is called the ‘Near 3kpc Arm,’ the other is the ‘Far 3kpc Arm.’ The Near 3kpc Arm appears to run from one end of the central bar to the other, then transitions into one of the two major spiral arms, the Perseus Arm. The Far 3kpc Arm appears to start at the end of the bar opposite the Near 3kpc Arm and goes to the other side of the bar, turning into the second major spiral arm of our galaxy, the Scutum-Centaurus Arm.

This hypothetical view looking down on the Milky Way Galaxy is courtesy of NASA.

Between the galactic bar and the Scutum-Centaurus Arm is another minor arm, called the Norma Arm. This arm spirals around the bar, becoming the Outer Arm, which runs outside of and roughly parallel to the Perseus Arm.

Between the galactic bar and the Perseus Arm is a minor arm known as the Sagittarius Arm. As the Sagittarius Arm spirals outward from the bar, it becomes the Carina Arm.

There’s a ‘star bridge’ connecting the Sagittarius Arm to the Perseus Arm. This bridge is known as the Orion Spur (sometimes called the Orion-Cygnus Arm). Our solar system is located on the inner rim of the Orion Spur.

Tightly packed groups of stars known as ‘globular clusters’ form a halo around the galactic center. Globular clusters are made up of hundreds of thousands of stars, tightly bound by gravitational attraction. Globular clusters are common in the halos of spiral galaxies (there are more than 150 globular clusters surrounding the galactic core of the Milky Way), but their formation remains poorly understood.

While there are many fantastic photos of the Milky Way viewed from our perch within it, I haven’t found a detailed map showing the names of the various structures that can be seen with the unaided eye. So, I decided to make my own (so as not to clutter the map, I elected to not label Messier objects).

I lack the skill and equipment to capture the entire Milky Way Galaxy in one image, so I broke it down into several photos (also, a good portion of the Milky Way can’t be viewed from our location because it extends far into the southern sky).

Here’s one example of the maps I made (along with the same photo, sans labels), showing the portion of the Milky Way toward the galactic core, looking through the Sagittarius arm, as seen from Earth.

In this map, the Milky Way begins in Scorpius on the southern horizon at the right, moves left to the galactic center in Sagittarius, then begins to flatten as the galactic bulge transitions to a flat disk, spanning the constellations Scutum, Aquila, and Cygnus (far left).

As you can see, the view of the Milky Way is one of faint clouds of stars, too thick to count, along with areas of darkness that, at times, appear mottled and, at other times, appear like they’ve been swept in a particular direction by an unseen force.

The dark areas, often referred to as ‘molecular clouds,’ are giant clouds of dust and gas that block the light of myriad stars behind them. We tend to focus on the star clouds, but the dust clouds are also worthy of notice since some of them are major areas of star formation – stellar nurseries, if you will.

How much detail you can see when you look at the Milky Way is dependent upon a number of factors. A clear, dark night is necessary to see its overall structure. But, atmospheric transparency (the amount of water vapor in the air) and ‘seeing’ (the degree of atmospheric turbulence) are also important. When these factors are all favorable, the resulting view of the Milky Way is nothing short of spectacular, even to the unaided eye.

So, take advantage of our dark night skies and become familiar with the galaxy we live in. View it as a whole or use binoculars or a telescope and break it into small portions. You can spend a lifetime observing the Milky Way and never learn all its secrets.

I’m currently watching two novae in the night sky, both within range of binoculars and small telescopes.

‘Nova’ is Latin for ‘new,’ as in ‘new star.’ But, a nova is not a new star. A nova is an event involving a white dwarf star (a small, dense remnant of a red giant star, no longer producing nuclear fusion) and a younger star converting hydrogen atoms into helium atoms through nuclear fusion.

When a white dwarf and a fusion-generating (a.k.a., main sequence) star orbit one another, gravity pulls them closer to one another. When sufficiently close, the dense white dwarf will gravitationally steal matter from its less massive companion. The white dwarf uses this accreted matter to create an atmosphere around it, mostly comprised of hydrogen.

The newly formed atmosphere is heated by the white dwarf to a temperature in which runaway hydrogen fusion begins. This fusion blows the atmosphere into space where the heated gas can be seen in visible light.

From Earth, we see a star that’s significantly brighter than before. This increase in brightness can last for weeks or even months. This event is known as a ‘classical nova.’ Some white dwarf-main sequence star binaries can repeat the process of accretion, fusion, and eruption. These are known as ‘recurrent novae.’

V1405 Cas:

V1405 Cas is a current nova in the constellation Cassiopeia. This nova was discovered at magnitude 9.6 on March 18th (depending on your location in the Santa Fe area, stars are visible to the unaided eye down to around magnitude 5.0 – 6.5). Earlier in March, an astronomer’s photograph of the area, including stars down to magnitude 13, showed nothing in the nova’s location. Currently, the nova shines between magnitudes 7 and 8.

Before dawn on April 8th, I photographed Cassiopeia as it rose in the northeast. I easily identified V1405 Cas, using the nearby open star cluster Messier 52 (M52) as a guide.

It’s worth noting that, initially, I didn’t find the nova in photos I took the previous evening (April 7th), when Cassiopeia was low above the northern horizon and well inside the Santa Fe area light dome. Due to these circumstances, my guidepost, M52, was not visible in the photo. However, once I found the nova in my pre-dawn photo of April 8th, I went back and discovered it in my photo of April 7th by comparing the star fields of the two photos.

The nova V1405 Cas appears near the open cluster M52 in Cassiopeia. The three identified stars in the bottom half of the photo represent the right side of Cassiopeia’s ‘W’ shape.

PNV J17581670-2914490:

A potential nova, identified as PNV J17581670-2914490, is currently under observation in the constellation Sagittarius. It was discovered just five days ago (April 4th) at magnitude 8.8. Spectroscopic analysis performed at Kyoto University confirmed that this is a classical nova. Official designation as a nova has yet to be given.

I photographed this object before dawn on April 8th at about magnitude 7.7.

Searching for this nova was like trying to find a needle in a haystack.

This object was more difficult to find because it’s located within the Large Sagittarius Star Cloud, where faint stars are abundant. I finally located it by laboriously comparing star locations in my April 8th photo with a photo of the same area I’d taken in February.

Nobody knows how long the novae in Cassiopeia and Sagittarius will remain at their brighter levels, but astronomers are observing them and recording data nightly, trying to learn more about novae and the conditions that lead to these violent events.