Summer Favorites, Part 2

(Plain Text Version)

Let’s continue our tour of summer showpieces with three objects close to the bright white star Vega:

The Ring Nebula

For most of its life, a star produces energy by combining hydrogen atoms in a fusion reaction. When the hydrogen is consumed, some sort of transition will take place. In this case, the outer layers of the star’s atmosphere have expanded and escaped. From our point of view, this gas appears as a ring. The core of the star shrank into a bright, super dense form called a white dwarf. Intense radiation from the white dwarf illuminates the gaseous ring.

Although the Ring Nebula is visible with a small telescope, bigger scopes reveal many colorful details.

The Double Double

Through a small telescope, the Double Double appears as two rather brilliant stars. These “stars” orbit each other. When viewed with a medium-sized telescope, the two “stars” are found to be two pairs of stars. The stars in each pair orbit each other. Hence the name “Double Double”: a pair of double stars.

T Lyrae

T Lyrae is a carbon star, a red giant star with an atmosphere rich in carbon. It has a vivid red-orange color due to the carbon compounds in its atmosphere. The red giant phase occurs after a star’s hydrogen has fused into helium. This happens late in the life cycle of the star.

Carbon stars are beautiful because their color contrasts with the neighboring stars. More importantly, the carbon is eventually expelled from the star and travels to other places. Much of the life-sustaining carbon on Earth came from ancient Carbon Stars.

The Hercules Cluster

Not too far from Vega and the Summer Triangle we find the Hercules Cluster. This is a globular cluster, a group of several hundred thousand stars which orbit a common point. These orbital paths are stable and continue for a long time.

If one lived on a planet inside a globular cluster, the night sky would always be bright. The view would be dominated by the stars of the cluster. When viewing through a telescope, it would not be obvious which objects are members of the cluster and which ones are farther away.

With a small telescope, the Hercules Cluster appears to be a small fuzzy blob. With bigger instruments, many individual stars can be seen.

July 25, 2021 0

Some of My Summer Favorites

(Plain Text Version)

In some places, the risk of COVID-19 is low enough that public star parties can resume. I enjoy observing on my own, but I really enjoy observing with a group of like-minded people.

Observe Now or Observe Later?

Star parties present a couple of hazards not found elsewhere. First, social distancing is difficult in the dark. A dark sky is great for observing, but it makes it hard to see your neighbors. Secondly, our eyelashes usually touch the eyepiece of the telescope. This could be a route for a COVID-19 infection.

Since the guidance of public agencies cannot cover every situation, it is best for the individual to evaluate the situation and decide whether to participate or not.

The Summer Triangle

In the Northern Hemisphere, three bright stars help us to find many interesting objects. The stars are:

Vega, the brightest of the three. Vega is white in color, and typically high in the summer sky. (Arcturus is also very bright, but it is reddish, and lower in the sky.)

Deneb is the bright star closest to Vega.

Altair is a bit brighter than Deneb, and farther away from Vega. Altair has a medium-bright companion, called Tarazed.

Which One Is Brightest?

This is a trick question! From our point of view, Vega is obviously the brightest. But if they are viewed from equal distances, we find that Deneb is one of the most luminous of all known stars. The visible-light output of Deneb is 950 times that of Vega. Vega appears brighter because it is much closer to us. If Vega and Deneb traded places, Deneb would be extremely bright, and Vega would be hard to find in the sky.

The Northern Cross and Much More

The post of the Northern Cross is made of five stars with Deneb at the “top.” Another two stars make up the crossbar. This figure is easy to find, and it is a guide to other sights.

If you are having trouble finding the Milky Way, the Northern Cross is a good place to start. The Milky Way covers the post of the cross and follows its general direction.

The star at the bottom of the post is called Albireo. Albireo is actually two stars close together, called a “double star.” There are many double stars, but the two stars of Albireo are famous for their beautiful contrasting colors. A telescope is needed to split Albireo into its two components. I won’t spoil your first look by saying what the colors appear to be.

To get a perspective on the universe, move the aim of your telescope through any part of the Milky way, and watch the stars go by. Most of these stars are so far away that you couldn’t reach them in your lifetime, even if you could travel at the speed of light. And this is only our home galaxy, one of billions!

(to be continued)

July 13, 2021 0

What is Happening to Betelgeuse?

A couple of weeks ago, I noticed that one of my favorite stars was a lot dimmer than usual. I soon found out that countless people have noticed the same thing. This star is Betelgeuse, in the constellation Orion the hunter.

Orion is a very prominent constellation in the winter sky of the Northern Hemisphere (summer in the Southern Hemisphere). Many features make Orion easy to find, especially the three bright stars which make up the hunter’s belt. Other striking features include two very bright stars: Rigel and Betelgeuse. Rigel is white, and Betelgeuse has a vivid orange color.

Betelgeuse and Rigel have been nearly equal in brightness, but now the dimming of Betelgeuse is easy to see. Unless you live in the North Polar or South Polar regions, you can step outside and see for yourself. Plus, no telescope is needed.

Betelgeuse is in its last, unstable, phase and will “soon” explode as a supernova. When this happens, you will certainly hear about it without the help of any on-line bulletins! Astronomers predict that it will be bright enough to see in the daytime for many days. It is far enough away that no harm to us Earthlings is expected.

Unfortunately, the word “soon” has a special meaning when spoken by an astronomer. It means: “In the next several hundred thousand years”. So, it could happen tonight, or it could be long after our lifetimes. So, we can look forward to watching the orange star continue to dim, brighten up or … whatever.

Keep lookin’ up!

John

Here is a detailed article, with a current picture of Orion.

Article by Space.com

Older article: Orion the Hunter – Part 1 – Easy to Find

Older article: Orion the Hunter – Part 2, Two Prominent Objects

January 5, 2020 0

Did You See that Meteor?

One reason I like the slogan, “Keep looking up” is that the night sky is full of surprises. Most of the objects in the sky don’t appear to change rapidly, but there are exceptions, like meteors.

Most meteors are very tiny specks of solid material, which make a subtle steak of light as they burn up in the atmosphere. These displays last for a fraction of a second, and are visible to those who are looking up.

At star parties, I often forget to look up while I am waiting to look through a telescope. Someone will exclaim, “Did you see that meteor?” Unfortunately I would have to answer in the negative. After that I try to watch the sky better.

Visibility of Earth satellites can be found on various web sites, but we don’t consult then very often. Thus a speeding satellite can take us by surprise. The International Space Station is the most prominent, but there are many other objects which can be seen by those who are looking up.

Northern or Southern Lights often appear in places far from the polar areas. During times of intense solar activity, they can be anticipated, but they can also appear unexpectedly. These displays may last for only a few minutes or a few seconds. Again, It helps to be looking!

So keep…

John

April 9, 2017 0

Astronomy Picture of the Day

SaturnIR_CassiniKakitsev_1024 — This image of Saturn, made by the Cassini space probe, was featured in NASA’s Astronomy Picture of the Day for April 3, 2017

If you wanted an enjoyable way to learn a little bit of astronomy every day, NASA’s Astronomy Picture of the Day is for you. It is found at:

https://apod.nasa.gov/apod/astropix.html

Every day, they show an interesting image and give an explanation by a professional astronomer. Called APOD for short, this site covers a very wide range of topics within Astronomy. Occasionally, related topics, such as Chemistry or atmospheric phenomena are presented.

Give it a try, and see what you think.

And keep looking up!

John

April 7, 2017 0

Orion the Hunter – Part 2, Two Prominent Objects

Today’s release of NASA’s Astronomy Picture of the Day features the Orion Nebula. Although this photo was made with a large telescope, many of its features can be seen with binoculars or a small telescope.

Astronomy Picture of the Day

In publications, discussions of the features of a constellation usually include a diagram. For Orion, let’s make an exception and try to find a few things using words only!

Betelgeuse

Of Orion’s two brightest stars, Betelgeuse (pronounced “Beetle juice”) is the distinctly orange one. It is at the “shoulder” of the hunter. Betelgeuse is classified as a “Red Supergiant” star. Its diameter is about 650 times that of our Sun. If it was at the center of our solar system, it would engulf Mercury, Venus, Earth, and Mars.

“Red supergiant” refers to a phase late in the life of many stars. Early in life, Betelgeuse was much smaller. When its supply of hydrogen fuel was used up, the star swelled to its current size. The next major event would be a supernova explosion. This is expected “soon” in astronomical terms, meaning in a thousand years, or so. This event would be quite spectacular, but may also be dangerous because of the gamma rays which would be released.

The Orion Nebula

So much for the end of a star’s life cycle. Moving to the other side of the Hunter’s belt, we find the Orion Nebula, which is full of stars at their beginning stages. The Orion Nebula is very close to the Hunter’s belt of three stars. In Northern latitudes, look below the star at the left of the belt. In Southern latitudes, look above the star the right. The Orion nebula appears as a fuzzy mass. In the city, it may not be visible to the naked eye.

The term nebula means “a cloud of gas or dust in interstellar space”. Virtually all of the gas in a nebula is hydrogen. The hydrogen in a nebula pulls together into a compact mass, through gravity. This process takes millions of years. If enough hydrogen is available, the molecules will be forced together tightly enough to start a nuclear fusion reaction. This is the birth of a star.

With a telescope, many more of Orion’s features come into view. Orion is a favorite of amateur astronomers, and an important study area for researchers. It is a constellation which “has something for everyone”.

Keep looking up!

John

March 12, 2017 1

Orion the Hunter – Part 1 – Easy to Find

This month, a prominent group of stars is easy to find just after sunset.

This constellation is Orion, the hunter. Orion is easily recognized by its “belt” of three bright stars. With a little bit of imagination, one finds stars for the head, a shoulder, a club, two feet, and a sword kept beneath the belt.

Some constellations are visible only from northern latitudes, others only from southern latitudes. A few constellations can be seen from any place on Earth. Orion is one of these. For northerners, Orion stands in the southern part of the sky. For southerners, Orion is in the northern sky. For those on the equator, the hunter will be directly overhead. For the few people who visit the poles, half of Orion is just above the horizon, and the other half is just below the horizon.

If a northerner and a southerner are looking at Orion, they will be facing each other. In the north, the hunter figure will be “right side up”, with the head higher than the feet. In the south, our hunter is “upside down”. (These discussions assume that Orion is viewed just after sunset in March.)

(more next week)

March 5, 2017 1

Star Parties – Part 2

A Star Party in an Unexpected Place

A month ago, I visited a cousin in New Jersey, who shared about his experiences at a local star party. I was surprised to hear that there was such an event in his area. This part of New Jersey is one of the most light-polluted areas of the country. It is about 6 miles from New York City.

This observing night was held at the William D. McDowell Observatory in Lyndhurst, NJ. At their viewing nights, they select objects which are bright enough to stand out against the bright background sky.

Here is more information about the McDowell Observatory programs:

Viewing Nights at the McDowell Observatory

It may seem odd to build an observatory in an area where the sky never gets truly dark, but it provides viewing opportunities for millions of people (but not all at the same time!). Consider the opposite extreme: an observatory on top of a mountain in the New Mexico desert. There would be outstanding viewing, but very few people would be able to travel the long distance to enjoy it. So, if you are in northern New Jersey, this ought to be fun!

The Best of the Best Objects to View

When you attend your star party, the astronomers will select objects that are interesting, and are in a good portion of the sky. Here are some of the most interesting things, roughly in order of visual impact:

The Moon – A quick look at the Moon reveals craters of all sizes, mountains, and flat dark “seas”. If you take more time to study the Moon, there is an endless variety of features, too many to describe here.

Saturn – for many people, the first look at Saturn through a telescope is an emotional experience. Even though larger and more detailed views can be found in books and on line, this is not the same as looking at the planet directly. Saturn is very bright, and has a sharp contrast to the background sky.

Jupiter and its moons – Because Jupiter is larger than Saturn, and is closer to us, it makes a larger image in the telescope. There are many features on the surface of Jupiter to enjoy. The main ones are the belts (dark bands which wrap around the globe), and the Great Red Spot (which nowadays is somewhat small and orange). The four largest moons of Jupiter are very bright, and move fast enough for changes to be noticed in a few hours.

The Hercules Cluster – This object is a globular cluster, a spherical collection of hundreds of thousands of stars orbiting a central point.

The Orion Nebula – This is an immense cloud of gas which is being transformed into new stars.

The Ring Nebula – This object comes from a very old star, which has shed a layer of its surface. This expelled layer has taken a ring shape, and is expanding in size.

Mars – Mars is called “The Red Planet”, but would be better described as orange. A casual view of Mars shows only a bright orange disk. The constantly moving pockets of warm and cold air in our atmosphere prevent a good view of the details of Mars. Persistence pays off, however, because there are occasional moments when a sharp view gets through. During these split-second opportunities, polar ice caps and dark areas can be seen on the surface.

Albireo – This is a “double star”, a pair of stars which orbit each other, or appear to do so. Albireo is unique for its brightness and the colors of its two stars.

The Double Cluster of Perseus – This is a pair of star clusters somewhat close to each other. They are called “open clusters”, which have far fewer stars than globular clusters. In the Double Cluster, many bright stars are beautifully arranged against the dark background sky.

The Andromeda Galaxy – This is the closest large galaxy in our stellar neighborhood. Through a telescope, it appears as a fuzzy oval, a little bit bigger than Jupiter. Looks can be deceiving, because the Andromeda Galaxy is composed of billions of stars, and is over two million light-years away!

That’s all for now. My goal is to post something interesting every Sunday night.

lookin’ up,

John

November 20, 2016 0

My First blog post

Greetings! I would like to start by thanking you for your patience with my lack of experience with on-line publishing. Let’s see if I can get going without too many mishaps!

I usually enjoy astronomy when I am looking up into the sky. However, interesting things can be found by looking at the ground! A year ago, as my wife and I were on an afternoon walk, our shadows looked strange. I was surprised to see how long they were and how well they lined up with the road direction.

Here’s the situation: We were out just before sunset on the first day of Autumn. We were walking Eastward on an East-West road. On the first day of Autumn, sunset is exactly in the West. So our shadows were a couple of hundred feet long, without going off the road.

Notice that our shadows are veering to the left. Since the Sun was still a little bit above the horizon, it wasn’t exactly in the West. It was a tiny bit to the South. Therefore, our shadows were pointing a tiny bit to the North.

I will back again soon!

lookin’ up,

John

August 28, 2016 0