My goal is to post enjoyable items about the skies. I don't have a schedule for new posts, so please check in from time to time. If you would like, you can sign up for email notifications about new posts. Enjoy!
For those who tried to see the predicted display of the Northern Lights, we hope you enjoyed the chance to go outside and take a look at the night sky.
I visited a semi-dark site near my home in Peoria, IL, but saw only stars and clouds.
We know that the Coronal Mass Ejection happened, but the bulk of it seems to have missed Earth. I received one report of a low, somewhat weak Auroral display in Northern Michigan (latitude 45 degrees North). See photo:
Aurora over Grand Traverse Bay, Michigan, night of October 30, 2021. Photo by Douglas Scobel
So, what will I do the next time an exciting prediction is made? I think you know.
Two days ago (10/28/21), the Sun released a large quantity of protons and electrons. This event is called a Coronal Mass Ejection (CME). This particular CME was stronger than usual, and is directed toward Earth. It is expected to reach Earth today (10/30/21).
CME’s can trigger vivid Aurora displays. This event is expected to strike our Northern Hemisphere, beginning with Europe and continuing to North America. Although Auroras are rare at Latitudes below 45 degrees, this event may be visible in places like Kansas, Illinois, and Virginia.
So, tonight would be a good time to look for the Northern Lights. It helps greatly to be away from city lights. Look to the North when the sky is fully dark.
Auroras are only moderately predictable, so we may not see anything…or we may see a huge display! Once in the 1970’s I was awakened in the middle of the night by my roommates to go outside and take a look. There were gray-white displays covering the entire sky. The city lights (in Ann Arbor, MI) couldn’t take anything away from the view.
Pardon me for not mentioning this sooner, but Astronomy At The Beach returns tomorrow!
Again, it will be an online event, with all-new presentations and online telescope views. Since we are online, we can visit the Southern Hemisphere: Maxi Falieres from Argentina will take us on a live a tour of the Southern Hemisphere skies! This will be from 10PM to Midnight EDT.
A lot of people would say that the Moon, Jupiter, and Saturn are the three most beautiful objects for small telescopes. For the next month, Jupiter and Saturn are well positioned over the southern horizon in the early evening. They are high enough to be free from disturbance by the atmosphere. For the next few days, the Moon will join them to make a celestial trio.
So, this is a great time to bring out the telescope and enjoy these three beauties.
The Perseid meteor shower has a reputation for being a reliable event. It reaches its peak on the night beginning August 12. Under a dark sky, roughly 60 meteors per hour can be expected. Unlike many other showers, it produces meteors a few nights before and after the peak night.
Although the Perseid shower is consistent in many ways, no meteor shower is fully predictable.
An Outburst on August 14, 2021
One day after the historical peak, an outburst was seen in the United States and Canada from 1:00-4:00 AM CDT. Approximately 120 meteors were observed per hour, about five times the usual number for this “off peak” date.
Scientists were not totally surprised by this outburst, because similar but smaller events occurred in 1993, 2018, 2019, and 2020.
Why Do Outbursts Occur?
Meteor showers are fed by streams of material which detach from comets as they orbit the Sun. These particles (called meteoroids) travel around the Sun with orbits similar to those of their parent comets. When Earth passes through one of these streams, the repeated streaks of a meteor shower are seen in the sky.
Comets don’t shed their particles in a uniform pattern, so the visible meteor count can vary from year to year, day to day, and even hour to hour.
How To Find an Outburst
One must be watching the sky at the right time! Usually, this time will be unknown. Since we all have busy schedules, it may not be practical take time to observe on nights other than the “peak” night.
To avoid an unproductive session, the sky can be scanned during periodic trips outside. It would help to watch for a few minutes, so that the eyes can gain at least some dark adaptation. (Full dark adaptation takes around 45 minutes.) For most locations, light pollution could hide many meteors. This technique is far from ideal, but it may reveal the unexpected!
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.
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!
I just heard that comet C/2020 R4 (Atlas) can be seen with binoculars, and is directly overhead for viewers in the Northern Hemisphere. Happy Observing!
A pair of eclipses is coming soon: a total eclipse of the Moon on May 26, 2021 and an annular solar eclipse on June 10, 2021. There are many resources available on line, but I just found one which makes it easy to get the details for your locality.
Today, the standard method of exploring the surface of the Moon or a planet is to land a robotic crawler loaded with cameras and scientific instruments. In my review of space missions, I was surprised to learn that these vehicles were very rare before the 21st century.
A Bit of History
In the beginning of the Space Age, missions were quite simple by today’s standards. The first lunar missions used a rather obvious procedure: transmission of data before collision with the Moon.
The first few years of space exploration were plagued by all sorts of problems. For every success, there were several failures.
Here is a timeline of the milestones:
1957: Sputnik 1, the first artificial satellite was launched.
1959: Luna 2 returned data before lunar impact.
1966: Luna 9 made first soft landing on the Moon, and returned photos and radiation data.
1969: Astronauts aboard Apollo 11 landed on the Moon.
1970: First of two Lunokhod missions landed on the Moon, and deployed the first robotic crawler to operate away from Earth.
1997: The Mars Pathfinder crawler was deployed on Mars and functioned for more than two months.
2004: Two vehicles were deployed on Mars, and functioned for a long time: Spirit (6 years) and Opportunity (15 years).
In summary, 4 decades elapsed from Sputnik 1 before remote crawlers became commonplace.
2021: Will It Fly?
We are on the verge of another major step in exploring our neighboring bodies: within a few days, Ingenuity, the first Martian helicopter will be flight-tested.
For a successful flight, many challenges need to be overcome, such as generating enough lift in the ultra-thin Martian atmosphere, and controlling the craft with limited human interaction.
Ingenuity has tested its rotating blades at low speed, and is scheduled to fly on Sunday, April 11. For details, see:
Real Simple Astronomy 