What's Up in the Night Sky -February

Fred Barrett | Feb 02, 2012

By Fred Barrett

Coronal Mass Ejections and spectacular views of the Aurora Borealis have been in the news lately and I thought that a review of Sun basics and what causes CMEs and flares was in order.

The Sun makes up 99.8 % of the mass of the solar system and most of the remaining 0.2 % is contributed by Jupiter. The Earth’s contribution is a tiny fraction of one percent! To give you an idea of the size difference, the Sun’s diameter is about 109 times the Earth’s diameter. It could contain 1.3 million Earths within its volume!

The Sun has an internal structure that is quite complicated but to describe it simply, the visible surface is called the Photosphere, which has a temperature of about 6000 °C. Below this is the Convective zone, which starts about 7/10s of the distance from the center of the Sun to the surface. Here columns of hot material rise from the inner Sun to the surface and columns of cooler material fall back down. Next there is the Radiative zone where heat travels only by radiation. The core of the Sun, where hydrogen fuses into helium and temperatures reach 14 million °C, stretches from the center to about 1/5th of the Sun’s radius. Here are some incredible numbers for you: every second, 700 million tons of hydrogen is converted to 695 million tons of helium and 5 million tons is converted to energy.

As you move away from the equator of the Sun, it rotates at different speeds and this is due to the fact that the Sun is a ball of gas and not a solid body like the Earth. At the equator it takes 25 days for one rotation while near the poles it takes 36 days. Sunspots can be observed moving faster near the equator than near the poles. Sub-surface portions take an average of 27 days per rotation.

As mentioned earlier, the Photosphere reaches 6000 °C but this temperature is much less than the Sun’s atmosphere. The region above the Sun’s surface is called the Chromosphere and temperatures can reach 10,000 °C. But in the region above the Chromosphere, called the Corona, 1 million °C is typical. The Corona spreads out to a volume larger than the volume of the Sun!

Flares and CMEs occur because the Sun rotates at different speeds at different latitudes. Magnetic field lines twist and warp and create ropes of magnetism. Where a rope rises through the surface from the interior of the Sun and then reenters the surface, 2 sunspots with opposite polarities are formed. You can think of this formation as a magnet with a north and south pole. When the ropes or field lines twist enough, they cross and energy explodes outwards in a Solar Flare. The largest, X class, can cause radiation storms in Earth’s upper atmosphere (M class are medium size and C class are small ones. Luckily our atmosphere and Earth’s magnetic field protects us when the flare’s energized particles hit us. Satellites can be damaged, though and communication radio waves that pass through the upper atmosphere can be disrupted.

On January 24th, a huge Coronal Mass Ejection occurred on the Sun that blasted out hot plasma and charged particles directly in the Earth’s direction. CMEs are similar to flares but are much more violent. The magnetic field lines that twist to form flares sometimes become so warped that, like a rubber band, they snap violently and break and then reconnect at different points. Gaps are created that allow plasma to explode out into space. Most CMEs and flares are pointed away from the Earth, thank goodness! CMEs bring charged particles of matter that interact with Earth’s magnetic field. When the particles reach Earth, they get compressed on the day side and stretch out like a long tail on the night side. When connection is made on the night side, a magnetic storm occurs that races back to the Earth’s upper atmosphere. The spectacular Auroras that could be seen in northern and southern areas quite far down from the poles for the best part of the following week, were one result of that huge CME on the 24th.

CMEs are especially damaging to satellites, electronic gear and communications due to their extraordinary violence. As well, voltages are induced in transmission lines from the magnetic storm and power blackouts can occur as the power system becomes overloaded.

I hope that my basic introduction to the Sun and its flares and CMEs tweak your curiosity enough to go out and do more reading on what is a very complicated subject.

Now let’s move on to this month’s highlights.

The Full Moon this month is at 4:54 pm EST. It is variously called the Snow Moon, little Famine Moon, Trapper’s moon and Storm Moon. All are very appropriate I would say!

An extremely thin Moon can be seen to the right of Mercury low in the west about a half hour after sunset on the 22nd. Mercury reaches its greatest height above the western horizon, about 10 degrees (1 fist width), on the 28th and maintains that position until about March 10th. Unless you have excellent eyesight, binoculars are recommended.

On February 9th, look East after 8 pm and watch for Mars rising to the left of a gibbous Moon (gibbous means that lighted part of the Moon bulges outwards). If you follow Mars from night to night, you will notice that it actually rises earlier as the month progresses. This is due to its retrograde motion (westward with reference to the stars) as Earth catches up to it. It will reach closest approach to Earth on March 5. Its disk grows from 11.8” to 13.8” during February. Good detail can be seen on its surface with a good telescope.

Between the 9th and 23rd the zodiacal light can be seen in the west. Watch for a tall cone of faint light between Jupiter and Venus. It is caused by light from the Sun reflecting off particles in the plane of the solar system.

On the 28th there will be a nice view of the Moon passing close to the Pleiades and on the 29th it will be near the Hyades.

In early evening, Jupiter can still be seen in the west with Venus far below it. As the month progresses, the distance between them shrinks and by the end of the month, they are separated by no more than 10 degrees. On the 25th, shortly after sunset, the Moon passes close by to the right of Venus and on the 26th, it does the same to Jupiter.

“The Beginner’s Observing Guide by Leo Enright is an invaluable companion for adventures in the sky and is available at the Sharbot Lake Pharmacy. It can also be ordered from the Royal Astronomical Society of Canada at www.rasc.ca/publications. A subscription to our very own excellent Canadian astronomy magazine “SkyNews” can be arranged at the RASC website as well.

Let me know how your observing has gone this month, especially anything unusual. I enjoy the feedback. If you have any questions or suggestions you can contact me through this paper or email me at This email address is being protected from spambots. You need JavaScript enabled to view it.. Clear Skies! Fred.

If you have questions or suggestions, Fred Barrett may be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it.

The Beginner’s Observer’s Guide by Leo Enright is available at the Sharbot Lake Pharmacy or by contacting the Royal Astronomical Society of Canada www.rasc.ca/publications, subscriptions for our very own excellent Canadian astronomy magazine, Sky News, are also available from RASC..