Week of April 28, 2014

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, April 28.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, May 2, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page. 

The Sun and the Moon

Sunrise is at 6:07 a.m. on Monday, April 28 and sunset is at 7:50 p.m. providing us with over 13 hours of daylight.  Even after sunset, the light from the Sun will still illuminate our sky for about one hour and 30 minutes.  This period of time is called twilight, which ends around 9:30 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 12:58 p.m. this week.

On the morning of April 29, 2014 there will be an annular solar eclipse.  An annular eclipse occurs when Moon passes between the Earth and Sun at one of the Moon’s orbital nodes.  These nodes are when the Moon crosses the Earth ecliptic.  The difference between a total and annular eclipse is the Moon’s apparent size in the sky.  During an annular eclipse the Moon’s disk appears a bit smaller than the Sun which allows for a little bit of the Sun to remain visible.  This ring of light is called an annulus hence the name annular eclipse.  Sadly none of the eclipse will be visible from St. Louis but you can watch the eclipse live at http://events.slooh.com/

The annular eclipse is only visible from Antarctica but the link above will broadcast the partial phases of the eclipse as seen from Australia.

Moonrise for Monday, April 28 occurs at 5:45 a.m.  Moonset will occur at 7:29 p.m.  On Monday the 28st the Moon will be exhibiting a waning crescent phase with 0% of the lunar disk illuminated.  New moon occurs on April 29.

International Space Station (ISS) Observing

There are no visible passes of ISS over St. Louis until the morning of May 13.  There are however a few nice morning passes of Tiangong 1 this week.  The best passes are on the mornings of May 2, 4 and 5.  Find out more about these passes in the table below.

Catch ISS flying over St. Louis in the evening hours starting Monday, April 28. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

02 May

 1.1

05:07:38

17

SW

05:09:43

59

SSE

05:12:38

10

ENE

04 May

 0.8

04:29:53

54

SW

04:30:26

79

SSE

04:33:24

10

ENE

05 May

 1.6

04:56:38

16

W

04:58:47

48

NNW

05:01:40

10

ENE

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/ 

The Planets Visible Without A Telescope

Venus

Venus is now well within its current morning apparition. It rises around 4:28 a.m. becoming easily visible by 5:15 a.m.  For those awake at this time you will see Venus in the southeast and Saturn southwest.  This planetary display nicely represents the path that the planets, Sun and Moon follow.  This path is called the ecliptic.  Take a look at Venus through a telescope and you will see it is phased much like the Moon.  Venus is currently exhibiting a gibbous phase with roughly 60% of the Venusian disk illuminated.

Mars

Mars is now in the constellation Virgo and will rise around 5:29 p.m. this week becoming visible shortly after the Sun sets.  For those awake around 9:00 p.m. look to the east and you will see a reddish-orange object high in the southeastern skies. 

We have now passed by Mars in our orbit and will continue to move further away each day.  We probably have another month or so to view the surface of Mars through a backyard telescope.  Take a look at the red planet now for it will be another 26 months before we get this opportunity again.   

Jupiter

Jupiter will be visible high in the western skies roughly 30 minutes after sunset.  As twilight fades you will see the bright stars Castor and Pollux just east of Jupiter.  Looking at these stars and then comparing them to Jupiter you will see that the stars are twinkling and Jupiter is not.  The twinkling you see is called scintillation which is a distortion of the stars light by Earth’s atmosphere.  Testing for scintillation is how you can distinguish stars from planets.  Jupiter is currently in the constellation Gemini the Twins. 

Saturn

Saturn rises by 8:40 p.m. and will be an easy target by 10:00 p.m.  Saturn is currently in the constellation Libra.  It forms a nice triangle in the sky with Libra’s two brightest stars Zubenelgenubi and Zubeneschamali.  If you watch Saturn in relation to these two stars you will notice it is exhibiting retrograde motion.  This is caused as the Earth catches up with a planet and then passes it by.  During this we see the planet from changing angles making it appear to move westward and then eastward again.  This motion is more prevalent with planets closer to us such as Mars.  If you go outside once a week for the rest of the year and sketch where Saturn is in relation to Zubenelgenubi and Zubeneschamli you will see this retrograde motion.  As retrograde motion is occurring that also means we are approaching another opposition with Saturn.  This occurs on May 10th 2014.  As we approach this date Saturn will continue to get brighter in the sky. 

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

The constellation for the month of April is Camelopardalis.  This little known constellation is found in our circumpolar sky so it can be viewed throughout the entire year.  With such visibility it might seem odd that most have never heard of let alone seen this large northern constellation.  The brightest stars in Camelopardalis only reach 4th magnitude meaning that for city observers these stars may need a pair of binoculars to be seen.

Camelopardalis is considered a modern constellation having only been recognized for about 400 years.  It is usually referred to as the giraffe as its name means spotted camel.  It was introduced as a constellation in 1612 by Dutch astronomer and cartographer Petrus Plancius.  Along with this constellation he is responsible for helping map out constellations of the southern hemisphere and introducing a few other constellations still recognized today.

Owing to its dim nature Camelopardalis can be difficult to find particularly in light polluted skies.  The first thing to do is find the constellation Perseus and Auriga.  Camelopardalis is north of these two constellations.  Next find the bright star Capella in Auriga.  About 8 degrees north of Capella you will find the two brightest stars of Camelopardalis called Beta and Alpha Cam.  Unfortunately there is no distinct pattern that stands out in Camelopardalis so you will have to use the star chart below to find the rest of the constellation.  Camelopardalis is north of the constellations Draco, Ursa Major, Lynx, Auriga and Perseus.  Its western boundary is at Cassiopeia and its northern boundary is at Ursa Minor and Cepheus.  This will be a difficult constellation to find but it is worth the effort as it will be the source location for a new meteor shower that will peak this year on May 24.  As we approach this new and potentially amazing meteor shower I wanted to help prepare readers for this event by introducing them to the constellation that houses its radiant.  Before we cover the meteor shower I want to first take a tour of this often over looked constellation.

http://www.iau.org/static/public/constellations/gif/CAM.gif  

The first object we will explore in Camelopardalis is its brightest star Beta Camelopardalis.  Beta cam is a G-class yellow supergiant star that is in the process of evolving off of its main sequence into the red giant phase.  It has started to fuse the helium at its core which has allowed for its outer atmosphere to cool and begin expanding.  Beta Cam is at a point where it should begin to pulsate as a Cepheid variable but has yet to start the clockwork like pulsations.  At a distance of 1000 light years this giant star with a luminosity that is 3300 times that of the Sun only shines as a 4th magnitude star.  This is because of Beta Cam’s distance and the dimming caused by interstellar dust. 

Another strange feature of this star is it was observed to suddenly display a bright flash of light in 1967  This and the fact that Beta cam is an x-ray source indicates the star likely experiences magnetic upheaval much like our Sun.  It is possible that the bright flash seen by pilots in 1967 was caused by a magnetic reconnection event similar to a solar flare on the Sun.   

Beta Cam is also a multiple star system.  A small telescope and large binoculars will be able to resolve a fainter companion (B-component) that is separated by 83 arc seconds.  The primary yellow supergiant star shines at 4th magnitude and the fainter companion shines at 7.4 magnitude.  The fainter B-component is itself a double star.  Very little is known about the second star in the B-component system.

To find Beta Cam first locate the star Capella in the constellation Auriga.  From here scan about 8 degrees north until you find the next brightest star.  This will be Beta Cam.  This triple star system will be the easiest thing to find that we cover for this month’s constellation.  Due to dim nature of the Camelopardalis our ability to star hop will be tested.  Use the map below to find Beta Cam and start familiarizing yourself with the other stars of Camelopardalis.

http://www.iau.org/static/public/constellations/gif/CAM.gif

The next object for the week of April 7 is the asterism known as Kemble’s Cascade.  Most of the objects we include in this section are cataloged objects that are normally some kind of star cluster, nebula or galaxy.  However there are some objects that are no more than a chance grouping or alignment of stars that stand out to observers and can be quite nice to look at.  One such asterism is known as Kemble’s Cascade.  This grouping of stars was discovered by an amateur astronomer named Lucian Kemble.  He was scanning Camelopardalis and noticed a string of stars that spanned about 2.5 degrees of sky.  It was later named in his honor and remains a popular target in the sparse constellation of Camelopardalis.

Kemble’s Cascade is a string of 20 stars, mostly 7th to 10th magnitude, which spans about 2.5 degrees.  The center of the string is accented with a 5th magnitude star.  The stars that make up Kemble’s Cascade are not related to each so what we see is just a chance alignment.  Following this cascade of stars to the southeast will bring us to an open star cluster called NGC 1502.  This cluster contains about 45 stars that will appear as a faint glow at the end of Kemble’s Cascade. 

To find Kemble’s Cascade start by locating Beta and Alpha Cam again.  From these two stars sweep about one binocular field to the west and you will see a line of stars that appear to cascade down from northwest to southeast.  This is Kemble’s Cascade.  Using the map linked below you will see a small curved grouping of four stars.  The eastern most of the four is set a little further off from the other three.  This fourth star is the bright 5th magnitude star in the middle of Kemble’s Cascade.    

http://www.iau.org/static/public/constellations/gif/CAM.gif

There are loads of interesting objects like Kemble’s Cascade scattered throughout the sky.  Backyard astronomy is not always just about finding distant galaxies or scanning the skies trying to complete deep sky catalogs.  Sometimes a keen eye and an imagination will allow an observer to see other chance alignments of stars like Kemble’s Cascade.  Reading monthly astronomy magazines and searching out observing forums is a great way to learn about many things that will not be included in the official deep sky catalogs.  

The Object for the week of April 14 is the spiral galaxy NGC 2403.  This galaxy lies about 12 million light years away and shines with an apparent magnitude of 8.4.  At this magnitude NGC 2403 is visible in binoculars but it will be considerately more difficult to see than a star with the same magnitude.  Stars have all their light concentrated into a singular point in the sky.  Whereas galaxies and other deep sky objects have more surface area so their surface brightness appears dimmer.  This is why when we see them they are frequently described as faint and fuzzy objects. 

To find NGC 2403 start by locating the star Muscida.  This star represents the nose of Ursa Major.  From here start scanning about 12 degrees to the east of this at a slight upward angle.  About two binocular fields to the east you should be able to find the dim patch of light that is NGC 2403.  Use the maps linked below to help you find this neighboring galaxy.

http://www.iau.org/static/public/constellations/gif/CAM.gif

http://www.iau.org/public/themes/constellations/#uma

The object for the week of April 21 is another spiral galaxy named IC 342.  This galaxy lies approximately 10 million light years away.  It shines with an apparent magnitude of 8.4 but as we discussed last week it will appear dimmer then a star with the same apparent magnitude.  It is a member of the IC 342/Maffei group of galaxies which is one of the closest groups to the Local Group of galaxies our Milky Way belongs to.  

To find IC 342 start by finding the two brightest stars in Camelopardalis, Beta and Alpha Cam.  Follow them north to the next brightest star Gamma Cam.  About two degrees southeast of this star is where you will find IC 342.  This galaxy is bright enough to be seen in binoculars but it will be difficult to find.  Small telescopes will also have trouble as the galaxy’s core is bright but the rest has a low surface brightness.  Follow the map linked below and you should be able to spot this galaxy.  Remember viewing conditions are important so try when the moon is not up and when humidity is low. 

http://www.iau.org/static/public/constellations/gif/CAM.gif

The final object we will cover this month is not an object but rather an event.  This event is the Camelopardalid meteor shower and is the singular reason I chose to cover Camelopardalis this month.  The Camelopardalids will not be visible until later in May but now is the time to start preparing for this new meteor shower.  As it is a new meteor shower there is some uncertainty regarding how good it will be.  This is normal for both meteor showers and the objects that cause meteor showers but it appears that the Camelopardalids will be a meteor shower to remember. 

So what do we know at this time?  First the source of this new meteor shower is debris left by periodic comet 209P/LINEAR.  This comet was discovered about 10 years ago and was last close to the Sun in 2009.  209P/LINEAR orbits the Sun every 5.09 years and will be making another perihelion pass this year in May.  It will only make it to 11th magnitude meaning it will only be bright enough for large telescopes baring an outburst event.  Analysis of the dust stream associated with the comet indicates the Earth will pass near enough that some of the particles will collide with our atmosphere triggering a meteor display.  Early predictions suggested that the Camelopardalids could produce visual rates of 100 to 400 meteors per hour at its peak.  More recent analysis of 209P/LINEAR’s dust output indicates the comet may be in the process of changing from an active to a dormant comet.  Based on this new information predicted rates have dropped to only 100 to 200 per hour.  In terms of the other big meteor showers the Camelopardalids will still be better.  Another observation made with the new research is that the dust tail of 209P/LINEAR is populated by larger debris.  This means that the Camelopardalid meteors should be bright.    

To observe the Camelopardalid meteor shower all you have to do is go outside and look north.  The radiant for this meteor shower is in the constellation Camelopardalis.  You will not have to look at the constellation but simply look in the general direction.  The predicted peak is set to occur around 1:29 a.m. on May 24, 2014.  Peak intensity could fluctuate before or after this time if we encounter density fluctuations in the meteoroid environment.  Most meteor showers will be active a few days before and after its predicted peak so it is possible that observations could be made before and after May 24th

There are a number of applications that have been created to enhance an observer’s experience.  There are astronomical applications that will notify you of upcoming events and there are a number of applications that will give you the weather conditions, maps of the sky and information regarding objects that can be seen.  NASA created an application that will allow you to record relevant information about the meteors you see.  Observations made in the field by professional and amateur astronomers are valuable for the study of meteor science and the comets that produce them.  Follow the link below for the NASA meteor count application.

http://meteorcounter.com/

https://play.google.com/store/apps/details?id=org.meteorcounter.MeteorCounter (Android version)   

In addition to watching the Camelopardalids you can also try to listen to them.  It is rare but meteors can produce sounds.  The simplest sound to hear is a sonic boom.  These are associated with meteors traveling faster than the speed of sound when they enter our atmosphere. The shockwave in the atmosphere triggers a sound wave that trails behind the meteor, meaning that sonic booms will be heard after you see the meteor. 

Another type of sound that is much rarer is an electrophonic sound.  These are produced when a meteor enters the atmosphere it is vaporized and it also excites the atmospheric gasses around it.  The plasma generated in this way interacts with and tangles the Earth’s magnetic field.  As the plasma cools it allows the magnetic field lines to snap back into their normal state.  Much like during a solar flare this activity triggers a release of electromagnetic radiation.  In the case of meteors a small amount of VLF radio waves are generated.  As these waves move at the speed of light the sounds they generate are heard as you see the meteor.  Even though these light waves oscillate in the audible frequency of the human ear they cannot be heard until the light waves pass through a natural transducer.  If this happens they can cause the material to vibrate and only then will we hear a sound.  Material that acts as natural transducers are frizzy hair, wires, wire rimmed glasses, pine needles and dry hay to name a few.  The sounds generated in this way have been described as short popping sounds, hissing or sizzling and are extremely rare.

The third way to listen to meteors is with a radio telescope.  Now before you blow this option off it is important to know that if you own a radio you have a very basic radio telescope.  With a simple digital FM radio you can tune in to a frequency that is static and periodically you will hear bumps, chirps and maybe another radio station bleed through for a brief second.  The plasma generated by meteors can scatter radio signals.  For the FM radio to work you will need to build a yagi antenna but with a little research this is pretty easy to do.  Here are a few links to websites that cover radio observation of meteors.

http://www.namnmeteors.org/NAMN_Guide.pdf (Chapter 5)

http://amsmeteors.org/ams-programs/radio-observing/

http://www.skyscan.ca/meteor_radio_detection.htm

Regardless of how you chose to observe the Camelopardalids this should be a great meteor shower.  Even though the predicted activity is a little lower than originally thought it should still be amazing.  Head to the darkest sky you can find and enjoy what could be the best meteor shower you will ever see.  

Our next Star Party will be held on Friday, May 2, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the ScienceCenter will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on May 2, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m. 

This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

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