21 October 2020

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. 

30 September 2020

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. 

27 August 2020

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. 

09 August 2020

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. 

Perseid Meteor Shower
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. 

11 July 2020

On seeing Comet NEOWISE

As suggested in this Sky & Telescope article from Bob King, "whatever you do, see this comet." We have a rare and wonderful opportunity to see a comet taking shape and revealing itself day after day. Comets come and go unexpectedly and often show promise that they might develop into something but then fizzle out and disappoint. Comet NEOWISE (also known as C/2020 F3) is living up to expectations and is now a naked-eye object visible in the early morning skies. You will need to get up early to see it for the next few days, but it is worth the effort. And if you don't manage to see it by the 15th of July, it will appear in the evening sky after that. The image on the right comes from a member of the San Francisco Amateur Astronomers, my old club, with NEOWISE over the Golden Gate Bridge. 
Image by Moshen Chan

The most important thing if you want to see NEOWISE is to have a clear view to the north, either the north-east in the morning or the north-west in the evening. This Sky & Telescope article provides detailed charts where to look for the next two weeks. As they point out, you will have best results for the next few days 1-2 hours before sunrise, or after the 15th 1-2 hours after sunset. 

I had to get up very early two days ago (3:00 am here in Munich) to see it. I took a short walk to the fields nearby my neighborhood where I had a clear view to the north and there it was, a lovely glowing coma and a long and smooth tail pointing upwards, away from the Sun, easily visible to the naked eye but a special treat in my 10x50 binoculars. If you have binoculars be sure to use them in the hunt. A telescope is unnecessary and the magnification will be too strong. 

Good luck finding NEOWISE and enjoy this rare spectacle. 

31 May 2020

15 minutes about: Our Place in the Universe

How can we possibly comprehend our place in the universe? I discuss this topic frequently during star parties and enjoy sharing my thoughts about how we can relate to the universe in a more tangible way. I created a 15 minute talk about this as part of an innovative science talk series in Munich, 15x4 Knowledge. The talk covers the various 'levels of scale' that define our universe, from our home planet Earth through the Solar System, Milky Way galaxy, the Local Galactic Group, to the Laniakea Supercluster. As the name of the series suggests, four speakers give 15 minute talks in a single the evening and it was an honor to be a part of their program. More videos from 15x4 Munich can be found on YouTube.

Click here to view the video "15 minutes about: Our Place in the Universe."

10 May 2020

Moon and Planets grace the morning sky

Moon and Planets - May 2020
This week, as the Moon passes through its waning phases, it will form some engaging patterns with three planets that are currently visible in the early (pre-dawn) skies. See image showing the change of location of the Moon from one night to the next, and the gentle interplay with Jupiter, Saturn and Mars as the Moon travels in its orbit around the Earth another 12 degrees eastward each day.

Jupiter has been gradually moving eastward as well, albeit considerably slower than the Moon. In fact, it takes Jupiter one full year (on Earth) to move the same 12 degrees eastward as the Moon does every day. And in addition, when we view Jupiter and the other outer planets from our view aboard spaceship Earth, we see a peculiar motion that takes Jupiter westward for a few months before continuing its eastward journey. We call this reverse motion 'retrograde' motion and in fact Jupiter is just now starting into retrograde and will return into the constellation Sagittarius for the summer before returning its eastward journey past Saturn into Capricornus at the end of the year.

This summer, Jupiter and Saturn will rise earlier and earlier and be visible the entire night from July onwards. But for now (in May) you will need to be up after midnight and before the break of dawn, around 4:30 am here in Munich, if you want to see this lovely morning alignment of the Moon and planets. I wish you clear skies and happy viewing!

Image courtesy Sky & Telescope.

26 April 2020

The Starlink Satellites

I have always considered satellites a part of observational astronomy. As an amateur astronomer, I enjoy simply looking up and trying to understand what I see in the heavens above. If a satellite happens by and I can watch its gentle arc for a while, I find that interesting and it enhances my enjoyment of being out under the stars.

Recently, SpaceX has been launching 100s of satellites into Earth orbit. The Starlink Satellite system will deliver high speed internet around the world. As a spectacle, I find the Starlink satellites fascinating to watch since they move in very large packs across the sky, not just single satellites but groups of them that move like a string of pearls across the sky for minutes at a time. I've observed these on many occasions over the past weeks. To see them, you will need a somewhat dark sky and a clear view especially toward the west. The website Heavens Above provides accurate information to help you locate times when the satellites will be visible based on your location on Earth.

Heavens Above - Starlink Passes
If you want to try to see the Starlink Satellites, your best bet is to find passes on Heavens Above when they will be appearing, which is typically within 1-2 hours after sunset based on your longitude and latitude. For city viewers, you will need to find passes that are at a brightness (magnitude) of 1 or 2. Higher numbers mean fainter satellites and they will be hard to spot. If you are in a darker location, you will be able to see passes down to magnitude 3 or even 4. Click on the image to the right to see an example, in this case based on my location in Munich, Germany.

The passes are quite impressive, with the graceful slow movement of a satellite from west to east being followed by a next satellite, and 15-20 seconds later another satellite, and so on. These chains of satellites are quite beautiful to see and if you are patient and look closely in the direction that Heavens Above advises, you will indeed find them. But you have to really pay attention to the cardinal direction (Azimuth, shown as east, west, north, south) and the height in the sky (Altitude, shown in degrees above the horizon).

There is controversy about these satellites. Because of the sheer quantity of them and the fact that they are bright enough to spot nearly every night, professional astronomers and astrophotographers are being disrupted in their work. SpaceX says they are working on ways to make the satellites less bright as they move up toward their final orbital altitude. The jury is out and we shall see how these satellites evolve over the coming months.

Postscript: on May 10th, 2020: SpaceX is working on plans to mitigate the impact of the Starlink satellites in the night sky, using a 'sunshade' approach.