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  • Rapt in Awe

    My Journey through the Astronomical Year

    Think of this as a "companion text" to this, the main web site. Not required reading, butI hope you'll find it interesting and helpful.

Events for April 2011: Saturn is the show – almost the whole show!

April 2010 Astronomical events

Note: While many events are visible throughout the world, the exact time and location in the sky can be dependent upon your latitude and longitude. Since I’m in the mid-northern latitudes (41.5N, 71.1W), specifics, where place-dependent, are calculated for this location.

Saturn is the real planet story for April 2011. Though Venus does continue to put in an appearance just before dawn, Saturn reigns in the night sky as the only planet visible.

This is the brightest Saturn has been in three years – nearly as bright as Arcturus, the guidepost star that dominates our eastern sky and is about as close to magnitude zero as you can get. Saturn is at magnitude  0.4 and easily found as it rises in the late twilight  about 30 degrees  – three fists held at arm’s length – south of Arcturus. Our “look east” star chart shows it well for mid-month, about 45 minutes after sunset.

Arcturus and Saturn dominate the eastern horizon during evening twilight in April - and, of course, are visible the rest of the night. Click for larger image. (Preapred from Starry Nights Pro screen shot.)

Click here to download a printer-friendly version of the above chart.

Unfortunately, the feature that makes Saturn most interesting – its rings – does require a small telescope. Binoculars – especially more powerful ones – may hint at the rings by showing the planet with tiny “ears” on either side, the way Galileo saw it. But the smallest telescope will reveal a charming image  of the planet and the rings, which are tilted now more than they have been in recent years and so are easy to spot.

Saturn reaches opposition in early April – which means it’s opposite the Sun  and thus rises as the Sun appears to set at nightfall.

As it grows darker you may notice an arc of third magnitude stars just above Saturn and running roughly northeast to southwest. The star of these three that is just a few degrees west of Saturn is one of the most famous and beautiful double stars in our sky, “Porrima.” A medium-size telescope trained on this star on a still night will show it is really two stars very close to one another and about as identical in brightness and color as two stars can be! It’s a charming sight that would not have been seen just a few years ago unless you had a very large instrument.  The reason is that the two stars are in a 169-year orbit around one another and reached their closest juncture just  six years ago.  Now they are slowly getting farther apart and thus easier to see as a pair.  When closest they are separated by about four times the distance between the Sun and Earth. When farther apart that separation is about 81 times the distance between the Sun and Earth, so the orbit is very elliptical.  If you have a telescope, you may enjoy reading more about them in the double star blog I do with my friend John Nanson, found here.

Catch the start of the morning planet parade!

Venus rises in the east-southeast about an hour before the Sun and at magnitude  minus four it is easy to spot in the pre-dawn – though keep in mind, even at daybreak it is only about 10 degrees – one fist – above the horizon. On April first from my location on the East Coast it may be possible to find a very slim, crescent Moon roughly 12 degrees north of Venus and about the same altitude. Using binoculars will help.

And using binoculars will be essential if, near the end of the month, you want to catch the start of this spring parade of planets in the morning.  This will get better in May, but on April 30 if you have an unobstructed eastern horizon and look from about half an hour to 15 minutes before daybreak, you may catch some of these planets.

Morning planets, April 30, 2011, as viewed from mid-northern latitudes on the East Coast of the US. (Prepared from Starry Nights Pro screen shot.)

The Moon will be a thin, waning crescent, but high enough so it should not be too difficult to see. Venus will be obvious. Mercury and  Mars are both first magnitude objects and so will be very difficult to spot as they rise in strong twilight. Jupiter – much brighter at Magnitude  -2 – should be easier, but being close to the horizon means you’ll be looking through a lot of air, and if there is any haze or clouds they’ll easily wipe it out. Binoculars are a must, but as daybreak nears, give it up! You don’t want to chance seeing the Sun in binoculars and thus damaging your eyes.  If you don’t find the planets within 15 minutes of daybreak put down you binoculars and enjoy the waning twilight.

April meteors

I hesitate to even mention these, but there’s always a chance.  In the morning on April 22 and 23rd the Lyrid meteor shower should put in a weak appearance. The Lyrids excite folks largely because they have unpredictable outbursts that on rare occasions can be spectacular. This year will not be one of those occasions if the experts are correct, and this meteor shower, weak enough as it is, will be competing with a Moon just four or five days past full. So, if you’re feeling lucky – very lucky … 😉

The Moon

  • New Moon – April 3, 2011
  • First quarter – April 11, 2011
  • Full Moon – April 17, 2011
  • Last quarter – April 24, 2011

And then there are those man-made objects in space!

There are some special astronomical events  that we don’t list here because they’re very specific to where you live and when you observe. These are events involving man-made objects in space – the passages of the International Space Station, Iridium flares, and other bright satellite and space craft passages. There are two excellent ONLINE sources for such events. I urge you to check both, see how they differ, and then make your own decision as to what works best for you.

  • The first is provided by Spaceweather, and you’ll find it by going to their Web site and clicking on the “Satellite Flybys” link on the top.
  • The second is the Heavens Above site, and while this requires you to register, the process is painless and free and the result is a lot of information that is specific to your location. You need to know your latitude and longitude, but you can get those by using the link in the “configuration” section near the top of the Heavens Above page. This is a one-time process. Once registered and logged in, study the menu – there’s a wealth of information on satellites and many other things.

Northern Lights!

And while on the subject of special events, the Sun is growing more and more active these days and that means a greater and greater chance of a beautiful display of northern lights.  This leads me to check Spaceweather frequently , for they will alert you to these displays for which there is only a day or two advanced warning.  Besides, it’s a fascinating web site with lots of interesting photos, worth checking every day anyways.

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