Whitby & District Astronomical Society

Saturn is steadily improving in the dawn sky and by mid month begins to rise before midnight.  The ringed wonder lies above ruddy Antares, chief star in Scorpius.  The moon passes close by on the 8th.

Meteor Activity

A number of lesser meteor showers occur during April.  The Virginids and alpha Scorpiids each have zenith hourly rates (ZHR) of around half a dozen, equating to average sporadic meteor activity levels.  The Virginids peak on April 7/8th but will be hampered by a waning gibbous moon.  The Scorpiids peak on the 27th.  but you will have to up before dawn to spot any. 

The month's most prolific shower, the Lyrids, peak in the early morning hours of the 23rd this year.  Zenith Hourly Rates are around the 25 mark and as it will be a 'no moon' period actual observed rates could reach 15 from 2am - 4am, with perhaps 7-10 beforehand.  Lyra; the constellation radiant, will be located low in the NE during the evening, and high to south before dawn.  The observer would therefore concentrate on other areas of the sky, not the radiant area. 

The Stellar Baker's Dozen Challenge

The lighter evenings of April offer up an interesting stellar challenge, testing the observing dexterity of astronomers - casual or otherwise in a race against time.  No, this is not a 'faint fuzzy blob' hunt, like the Messier marathon, the exact opposite in fact, more of a sprint really.  This is all about spotting first magnitude stars; those ranked brightest in the sky at the same time. 

Piercing the spring twilight dotted around the sky, no less than thirteen are currently visible (we will count Castor), more than at any other time of year.  However the window of opportunity in which to identify these stellar jewels rapidly diminishes as we head deeper into April, from little over an hour at the start, to just fifteen minutes by mid month. 

You will require clear views right around the horizon and complicating matters further, a number of bright planets may confuse the unwary. 

Let us assume it is April 8th, at which time twilight deepens around 9pm.  Our first port of call lies over in the west, where the mighty hunter Orion is about to lose his right toe, marked by bright Rigel, (1) below the horizon.  But, you also need to spot Spica (2) low in the south east when Rigel is above the horizon, so you will need to be quite sharp in doing this.  Got both? Good.  Now look above Orion's three belt stars which are aligned parallel to the west horizon, to locate the conspicuous orange hue of Betelgeuse (3).  A hand span to the right of Betelgeuse and slightly closer to the horizon another orange star, Aldebaran (4) chief star in Taurus is visible in the 'V' of the Hyades cluster.  A word of caution here, the brilliant 'star' visible in the W is in fact the planet Venus, and both Mars and Mercury will also be visible to the lower right towards the end of the month.  Low in the WSW the brightest proper star in the sky - sparkling Sirius (5) is quite unmistakable. 

Having picked out this first clutch of stars, there is no time to waste, so raise your gaze somewhat higher, to pick out the next wave of luminaries.  Starting in the SW again seek out the bright solitary white hue of Procyon (6) in Canis Minor located above Sirius and to the left of Orion.  Due west and higher still, Castor (7) and Pollux (8) denote the twins of Gemini, which is descending feet first down toward the horizon.  At a similar altitude to Gemini further across in the WNW and above Venus, shines brilliant Capella (9) in Auriga, the only one of our bright seasonal winter stars not to set, being circumpolar from our latitude.  Capella will spend the summer months arcing low above the north horizon. 

Turn and face due south, where midway up you will encounter bright Regulus (10) in the 'sickle' asterism of Leo.  The prominent 'star' to the right of Regulus is Jupiter.  Our next star is located due east, where brilliant Arcturus (11) in the constellation of Bootes is very noticeable, its soft orange hue contrasting markedly with Sirius, the only star of the baker's dozen brighter.  Now for a test within a challenge, see how far into April you can spot both Sirius and Arcturus above the horizon at the same time. 

We still have a couple of stars to indentify, so direct your gaze toward the north, where low in the NE brilliant steely blue Vega (12) resides in the constellation of Lyra.  Vega almost rivals Arcturus in apparent magnitude, but unlike the 'guardian of the bear" it is circumpolar from Whitby's latitude.  Our final star, Deneb (13) is located just above the NNE horizon and appears much less brilliant than Vega but is by far the most distant of the stars visited.  It too is circumpolar and along with Vega constitutes two of the three stars forming the 'summer triangle'.  In less than three months, only Arcturus, Capella, Deneb and Vega will remain of our original stellar baker's dozen, the rest having set.  So, are you up for a fun observing challenge, it should only require 5 minutes (at most) to complete. 

Solar Eclipse

You have to say that all things considered, we were rather fortunate to catch more than a fleeting glimpse of the partial eclipse on the 20^th.  The forecast did NOT make for pleasant viewing, but at least from Whitby the cloud fragmented just enough, and at the right time, for the greatest show ‘off earth’ to be viewed by the masses.  From the Whitby pier band stand (our location for the event) light levels certainly dimmed, the temperature dropped, things seemed to go still, around the time of maximum obscuration- just after 9:35am.  Even the seagulls fell quiet for a while!

Wherever you managed to watch it from, I hope you were as delighted, impressed and moved as we were, it will be another 11 years before another solar eclipse of similar magnitude will be visible from our shores, although a couple of lesser events will occur before then. 

Have a look in the WDAS Gallery for some Members images of the Eclipse, and please e-mail us your own.  Check-out this great animation by Keith D made from 54 images of the Eclipse.

The Lion and the Serpent

Compared to the departing stellar canopy of winter, at first glance the spring sky may seem rather less inspiring.  Yet, appearances can be deceptive and there is much to wonder at amongst the constellations now arranged across the south and east.

Our tour commences as darkness falls around 21:45h.  By then Leo, the most readily identifiable spring constellation is located due south.  The head and mane of the lion is marked by the distinctive star asterism known as the ‘sickle’, although some people view it as a backwards question mark.  At the base of this arrangement shines prominent Regulus, Leo’s chief star, and faintest of the 1^st magnitude stars.  Regulus sits just above the ecliptic and as a consequence is sometimes occulted by the Moon and on very rare occasions by a planet. 

In antiquity; from 4000 to 2000 BC Regulus was counted as one of the four Royal stars, those bright stars closest to the equinox and solstice positions.  During this period Regulus was nearest the summer solstice position, but the effect of precession has subsequently shifted this point well away. 

To the left of the sickle, a ‘triangle’ of stars depicts the hindquarters of Leo.  Just beneath an imaginary line joining Regulus to Denebola, the rearmost star of this triangle, a number of galaxies are found, some of which are visible under good seeing conditions in smaller scopes (see chart). 

Decidedly miffed by the loss of her pet, Hera then pitted Hercules against the multi headed Hydra, which he overcame by using flaming arrows to cauterise the neck-stumps thus stopping the heads from regenerating.  Hera; who saw the snake was in trouble, sent a giant crab (Cancer) to assist Hydra.  In the ensuing battle Hercules also crushed the giant crustacean.  A distraught Hera then placed both monstrous creatures in the heavens.