Red-Orange Stars and a Planet: Betelgeuse, Aldebaran and Mars

Mars is making a splash in the evening sky this winter, and it's near two stars that appear quite similar in color and brightness. Mars is presently in the constellation Aries, which is next to the next Zodiac constellation Taurus and the bright orange-giant star Aldebaran. The two objects are quite similar and at a glance, one can see the colors shining through. But if you move just a little further east along the line that connects Mars to Aldeberan, you will find the bright red-supergiant star Betelgeuse, which marks the upper left shoulder of the giant constellation Orion. Betelgeuse is one of the largest objects in the Milky Galaxy, a truly giant star that would encompass the orbits of the planets nearly out to Saturn if it was in the same place as our Sun. 

Mars is slowly working its way eastward across the sky, such that in a few weeks it will be very close to the Pleiades and continue its march across Taurus and then through Cancer. Mars has had a busy year, with its closest approach to Earth last year and now getting ready to host three new spacecraft that will land there in the coming days, the UAE Hope spacecraft, the Chinese Tianwen-1 spacecraft, and the NASA Perseverance lander with a new rover ready for further exploration and discovery on Mars. 

Image courtesy Sky & Telescope. 

The Great Conjunction of Jupiter and Saturn - Dec 21st, 2020

We will witness a very rare and beautiful spectacle in the coming days. On December 21st, Jupiter and Saturn will be less than one-tenth of a degree apart from each other as seen from Earth, a rare alignment that happens only every 400 years at this extremely close separation. 

The Great Conjunction

Great Conjunction: Conjunctions occur often in the heavens, as heavenly bodies pass near each other, on in the less common scenario where the Moon covers stars and occasionally planets, and as planets and asteroids cover stars. In any case, a conjunction is usually a fascinating thing to see, particularly up close if you have binoculars or a telescope. When Jupiter and Saturn pass near each other every 20 years, we have a 'Great Conjunction' in which the two massive planets are very near each other. But every 400 years, the alignment is extremely good and we have both objects in one telescopic field of view, as portrayed in the image to the right. 

How to See It: The two planets will be visible only for a short while after sunset, and you will need a clear view to the west to see this. Look directly to the southwest of the point of sunset an hour after the sun goes down. If you have a telescope or binoculars, this is definitely the time to get them out and put them to work. If you can, look for the pair on Saturday 19th or Sunday 20th to get an idea where to find them. They will be in roughly the same place on the 21st, but through the telescope or binoculars the difference from one night to the next will be dramatic. 

Learn More: There are excellent articles online if you want to learn more about this rare and exciting event, on Scientific American or Earth-Sky. I find all of the detailed planetary geometry fascinating, and fun to understand how such alignments occur and can be accurately predicted. 

I wish you clear skies and happy viewing! 

Image courtesy Earth-Sky. 

Geminid Meteor Shower 2020

The Geminid Meteor Shower peaks on Sunday 13th and Monday 14th. This year, it will be especially well timed with the New Moon, meaning that there will be no moonlight to brighten the sky, leaving the sky dark and at its finest for a meteor shower. 

Fireball

What causes a meteor shower? Every day, there are dust particles and small objects flying into the Earth's atmosphere from space, sometimes randomly, sometimes predictably, causing a 'shooting star' in the night sky. And sometimes with great surprise, a larger piece of an asteroid will fly into the atmosphere and become visible as a Fireball, as was the case two weeks ago in Japan. The Geminids are predictable, one of many annual meteor showers that are caused when the Earth travels through the remnants of a comet or asteroid that has orbited the Sun sometime in the past, leaving a debris stream in its wake. 

What causes the Geminids? Every year on December 13th and 14th, the Earth travels through such a wake (of an asteroid named 3200 Phaethon) and we have a lovely meteor shower, as the dust and sand particles impact the Earth's atmosphere at high speed and heat up the air, causing it to glow as the meteor hurtles toward Earth. Nearly all of the particles in a meteor shower never reach the surface of the Earth, but those that do (called Meteorites, once they've landed) are of great scientific interest. 

How to see the Geminids: For any meteor shower, you want to find a dark location where you have a wide horizon. You don't need to look in any one direction, but ideally relax on a blanket or chair and simply look up, and have patience. And of course, for most of us it's winter and it's cold, so you need to dress extra-warm. 

If you want to learn more, this helpful article from Astronomy Magazine provides a great deal of information about the Geminids. 

Happy Viewing, and stay warm! 

Image courtesy of ESO. 

Share the Night Sky - Broadcast on KPOO

During the recent Bay Area Science Festival, I had the privilege of sharing the night sky with DJ Marilynn and the listeners of KPOO during a special broadcast on Thursday evening October 22nd. Our hour-long broadcast features many different topics: 

• How to find a good spot for stargazing in the city, and how to prepare for looking at the night sky. 
• How to find planets such as Jupiter, Saturn and Mars this fall and winter, along with the constellation Sagittarius. 
• How to find the Summer Triangle and connect it to the Milky Way. 
• How the view of the sky changes when viewing from different places around the world. 
• How to understand the motion of the constellations in the northern sky, featuring Cassiopeia and the North Star. 
• How to enjoy a view of Orion the Hunter later in the evening. 
• How to further your experience with the night sky. 

Click here to listen to the broadcast. 

Image courtesy of KPOO-FM.

A Fall Triangle

There are popular alignments of the stars that mark summer and winter, but not in the fall ... that is, until Thursday October 22nd when we will have a brief but impressive 'Fall Triangle' as a result of the waxing Moon passing near Jupiter and Saturn in the evening sky. To see this you will need a clear view to the south, but the three objects are easy to find and a pleasure to view all in one compact triangle. If you have binoculars the view will be even more spectacular. The day before and the day after the Moon will no longer be close enough to form the triangle. So take a minute to savor the sky on the 22nd and you won't be disappointed. 

As an added bonus, take note of the position of Jupiter and Saturn. If you pay close attention over the next two months, you will see the gap between them closing day by day. Jupiter is heading for a conjunction with Saturn that will culminate in a very close encounter in late December. Keep your eyes on the sky! 

Image courtesy Sky & Telescope. 

Approaching Mars

If you have been attentive to the night skies lately, you've most likely noticed a very bright orange/red object in the evening hours toward the east. That is Mars, the Red Planet, and we are fast approaching Mars for a close alignment that will bring us to the closest approach in over two years, culminating on October 6th. It will remain a distinctive evening object for the coming months, but the month of October is when you will see Mars shining at its brightest. 

Every 26 months we have a close encounter with Mars. The last one, in 2018, was even closer than this year. However, for those of us in the northern hemisphere Mars was low on the horizon for most of the night. For the 2020 close encounter with Mars, we will get a better view of the red planet, as it will climb higher across the night sky in October and through the end of the year. 

In addition to the close approach on October 6th, Mars will be at opposition on October 13th. For more details about opposition, I recommend this Earth Sky article by Deborah Byrd (scroll all the way to the bottom for a great Mars Opposition chart). And if you have a telescope and want to use this close encounter to get a close up view of Mars and some of its surface details, I strongly recommend this Sky at Night article complete with weekly views of what to look for on the martian surface. I will take advantage of this month to try to make out the martian South Pole and some of the surface features with my 5 inch reflector, and I will report on that in a future post. 

Image permission Wikimedia Commons. 

Update on October 21st: I have tried to view Mars with my 5 inch reflector telescope. Unfortunately, that size telescope is simply too small to provide the resolution needed to see the features on the martian surface. I suspect that a camera and some long-term exposures could help, but without an 8- or 10-inch telescope, I don't think it will be possible to truly see the surface details with the naked eye. 

Late Summer Waxing Moon

Who doesn't like looking at the Moon? It's such a treat for everyone, and is a lovely sight. For us Northern Hemisphere dwellers, there is a unique period of time each year in the late summer when the waxing Moon plays out across a low swath of southern sky, never getting very high into the sky. That unique period of time is now, and the Moon is making things more interesting by passing close to Jupiter and Saturn. 

For the last many days I've watched the waxing Moon emerge from the new phase into a thin crescent and then slowly toward first quarter. All the while it hugged the southwestern horizon, keeping low in the sky and making it more challenging to find. Now the phase has advanced to gibbous (between first quarter and full Moon) and all the while, the Moon only gets high enough to be seen if you have a clear view to the south. And for me, when I see this low-flung Moon, I know it is late summer. There is a technical reason for this. The waxing phases of the Moon occupy the sky where the Sun will be for the coming six months ... and that will be in the Fall and Winter seasons where the Sun does not rise too high above the southern horizon. There is a beautiful symmetry to the Sun and Moon and since we have one complete lunar phase every 29 days, we can see the entire flow of the seasons every month if we know how to look at the Moon. 

Over the past several years the late summer sky has featured Jupiter and Saturn low in the south. This year Jupiter will overtake Saturn in a series of 'conjunctions' which have already started, and will run their course by the end of the year with a spectacular alignment of the two planets in December (mark your calendar for Dec 21st). Saturn moves around the Sun very gradually from our point of view, and Jupiter faster but still quite gradual from year to year. The effect of these gradual movements is that these two giants have been lurking low in the southern sky during the Summer for the past years and for the coming years ahead. So as I've observed this unique time of year when the waxing Moon traverses a deep southerly course in the late summer, it's had the added beauty of a monthly encounter with Jupiter and Saturn. That will happen this week, on Friday 28th. You will need a clear view to the southeast to really enjoy the spectacle. And who knows ... perhaps you will discover this lovely configuration and the low waxing Moon in late Summer as something you will look forward to every year. I sure do. 

Image courtesy of Sky & Telescope. 

Perseid Meteor Shower 2020

The Perseid Meteor Shower has already started and will peak over the coming days, on August 11, 12 and 13th. This shower is one of the most reliable meteor showers of the year and as it peaks during generally warm weather for the Northern Hemisphere, it's a pleasant and easy-to-watch astronomical event that can captivate and amaze. 

Seeing the Perseids: seeing any meteor shower is easy, but getting the most out of the evening takes a little planning. First of all, you want to find dark skies, ideally away from city lights. Second, you need to reduce all local lighting to a minimum, including houselights and if possible, streetlights (for example, move to a part of a garden or park where streetlights are not directly visible). Third, you need a comfortable place to relax, ideally on a recliner chair or on a blanket on the ground so you can simply look up in all directions. Finally, you need to have warm clothing because even after a warm day the evening temperatures can drop quite quickly and if you are lying still in the open air, you will very quickly feel the effects and the Perseids will lose their appeal. 

There are two more factors that has a big impact on seeing the Perseids, one you cannot control (the phase of the Moon) and one you can (when to watch). The Perseids in 2020 are better positioned than some years because the Moon will not rise until well after midnight, allowing more viewing time in the late evening and early morning hours. In general, the best time to watch any meteor shower is after midnight (for reasons you can read about here), so your best bet is to get out late evening to start your viewing, and stay out until the moon rises (if you can stay awake that long!). 

Why are the Perseids so reliable? The Perseids, like most annual meteor showers, are caused when the Earth travels through a debris field that is also orbiting the Sun. In the case of the Perseids, the debris field is from Comet Swift-Tuttle. The American Meteor Society has an excellent article that explains some of the science of the Perseids, if you want to learn more. 

Best of luck, and clear skies! 

Image courtesy of NASA.