SKYMATTERS Blackrock Castle Observatory www.bco.ie Download monthly skymatters newsletters from www.bco.ie/skymatters April 2018
peaks on the 22/23 and is best observed in the early morn- Things to watch out for ing, between 2:30 and 4:30 to avoid the glare of the moon.
April 1 April 29 The Moon is just past full at the beginning of the month, mak- Mercury’s greatest eastern elongation will occur on this date. ing it a less than ideal date for observing fainter objects. This is the point of Mercury’s orbit where it appears the fur- However, Venus is still visible to the west just after sunset, as thest from the sun, rising ahead of the sun in the early morn- well as Saturn, Mars and Jupiter in the morning. ing. It is an incredibly difficult planet to spot, but it’s proximity to the sun means that it is safer not to use a telescope
April 15-21 April 30 Dark Sky Week is celebrated internationally around the new moon in April. The New Moon is already a great time to star- The Full Moon rounds out a great month for stargazing, see gaze, but we can all make the sky darker by turning out our the image below. lights. Visit the official website, http://www.darksky.org, for
more suggestions and tips for how you can take part and protect dark skies.
April 16
April’s New Moon falls in the middle of the month. This is a Here is the moon great night to look for fainter objects free from the light of the at it’s fullest.. moon. It is even better to head out to a dark sky and catch Highlighted in red is The Sea of the Milky Way and other faint objects with just your eyes. Tranquility
April 22/23 The Lyrids Meteor shower runs from the 16th to the 25th and is an average shower, producing roughly 20 meteors an hour that radiate from Lyra (in the Summer Triangle). This shower
On the left, we see sunrise on the 6th. These planets maintain a simi- lar position all month, with Jupiter leaving the sky last after all the other stars and planets are blocked by the light of sunrise. The bright star between and slightly below Saturn and Jupiter is Antares, the heart of the constellation Scor- pius. Above Is Virgo, with its brightest star Spica highlighted. The Just a smattering of almost 50 galaxies visible in the direction moon is in this position on the first of April and is in a similar of Virgo. Vindimiatrix is Virgo's arm/shoulder while Denebola is position on the 29th.. the last star in the constellation of Leo, just to the west of Virgo.
Virgo and our Neighborhood Virgo is one of the biggest constellations though being mainly comprised of fainter stars makes it difficult to find. One of the best ways to find objects in the sky is by starting with more familiar objects, such as the Big Dipper. If you follow the curve of the Big Dipper’s handle a little fur- ther you’ll come to Arcturus, shown in the top left of the above image. After “arcing to Arcturus” you “speed on to Spica”, continuing past Arctu- rus in a straight line until you hit the next bright star. This brings you to the centre of the constellation.
Being one of the signs of the zodiac puts it near the ecliptic and in the path of the Moon. You can use the Moon to find Virgo easily on the 1st and 29th. You can also use the other signs of the zodiac as stepping stones, for example Leo is just to the west of Virgo if you are looking roughly south. The planets also follow the ecliptic and for April Jupiter is in Libra, just to the east of Virgo when facing south.
The Virgo cluster of galaxies and our local group of galaxies (including the Milky Way, Andromeda, Triangulum and many dwarf galaxies) are part of the same super group. These galaxies may not be our next door neighbours like Andromeda, but they are close enough to affect us. Our group of galaxies and the Virgo group are slowly coming closer together. This makes the area of Virgo one of the best places to point your tele- scope if you’re looking for galaxies. The image above, right, shows the locations of just a few (nearly 50) galaxies.
With so many galaxies to choose from, it’s useful to pick a few to start with. Many of the bigger and brighter deep sky objects were catalogued by a French astronomer named Charles Messier. The Messier Objects are well known and usually quite easy to see even in smaller telescopes. Some of the Messier objects in Virgo are M49, M87, M60 and M87, all examples of huge elliptical galaxies, M100, M61 and M90 are a more familiar shape, all being spiral galaxies of various types. Overall, there are 16 Messier objects in the group and as many again that are tracked in other catalogues. It is a rich area of the sky for any telescope astronomer.
See the last page for some telescope purchasing tips. Stephen Hawking may have been a big proponent for the existence of black holes, in fact it was his calculations that revealed them to be pos- sible. However, he bet Kip Thorne, also a physicist, a magazine sub- Cygnus low t o the North-East just before midnight and high to the South-East just before sunrise. scription that Cygnus X-1 wasn’t such an object. This way he couldn’t The rough location of CX1 is marked with a red dot .The three lose, either his research was wrong and he won the bet, or he lost the named stars form the summer triangle. Albireo is the star at the end of Cygnus, directly below Vega. bet but vindicated his research. The bet was made in 1974 and con- cluded in 1988, with the community 95% certain that it was a black hole.
The Triangle and the Swan The Summer Triangle is three stars, Vega, Deneb and Altair, so named because they are visible from sunset to sunrise in the summer months, but dip below the northern horizon for some portion of the night for the rest of the year. They are bright enough to be seen even in most cities, and as we are getting close to summer, they’re visible for a large portion of the night at this time of the year. The triangle will rise around mid- night to the North-East and vanish high to the South as the sun rises. Despite being easily spotted and its use in telling the time of year, these stars are not a constellation. The ancient Arabs viewed it as a constellation, but the Greeks put these three bright stars into three separate con- stellations. Altair in Aquila (the Eagle), Vega in Lyra (the Lyre) and Deneb in Cygnus (the Swan).
Cygnus the Swan is one of the constellations that the Milky Way appears to pass through, making the area a dense field of stars when viewed through a telescope. One of the best beginner objects in the sky lies at the head of Cygnus, near the centre of the triangle. Albireo appears to simply be a bright star to the naked eye, but a closer look reveals it to be two stars. A binary pair of stars is two stars orbiting each other, and in Albireo's case each star is a distinctly different colour, one being orange-gold and the other being much bluer. It is one of the best examples for the difference even a small telescope can make to what you see above you.
One of the most exciting objects in space for many astronomers is a Black Hole. Old or young, the idea of such an object is fascinating for many. Infinitely dense, inescapable even for light, a point in space where the laws of space and time as we know them break down and cease to make sense. Given that theses objects don’t emit light, for a long time there existence was inferred from how objects around them moved. If a giant star starts to orbit in a strange way, or appears to sling shot around an empty patch of space, a black hole would be a candidate explana- tion.
Stephen Hawking suggested that these objects might emit other wavelengths of radiation (i.e., Hawking Radiation). Cygnus X-1 was the first black hole to be officially recognized. It is constantly siphoning material from a companion star, giving it a steady output of X-rays. We might not be able to see a black hole, but their companion stars are stars, and the companion of Cygnus x1 is visible through a telescope near the middle of the constellation, marked in red in the above image. You might not see it, but you’ll be looking at a black hole. Tips for Buying Your First Scope Website of the month With so many options, buying your first telescope can be a little daunting. Here are a few points to consider if you are planning on picking up your own window www.ktectelescopes.ie on the universe around us. Ktec Telescopes are an Irish telescope supplier that stock a • Figure out what’s most important to you. Do you have a certain budget? Is there wide range of brands, sizes and something in particular (Saturn’s Rings, other galaxies) that you really want to see? types of telescope across a Is this a telescope for a particular place or does it need to be mobile? broad price range. They also have their own selec- • Think about complexity. Is this a telescope you want to be able to grab and point tion of guides for buying tele- without delay? Or will you be setting up the telescope in advance of a long observing scopes, whether it’s your first session? or you’re a seasoned astrono- mer looking for something more • See which type of telescope is best suited to you. Refractors are easy to use but powerful. require some maintenance. Reflectors can require a lot of adjustment but are usually lighter than their refracting counterparts. Catadioptric telescopes take very little Quote of the month
maintenance and are great for nearby objects (Planets, Moons). However, they are “I believe alien life is quite com- usually the most expensive option. mon in the universe, although intelligent life is less so. Some • If you’re tech savvy or want to save time, a GOTO scope can find objects for you to say it has yet to appear on plan- look at. Some have their own integrated remote control, others require an external et Earth.“ computer, such as a laptop. From “Stephen Hawking's Uni- verse”, aired in 2010. • Finally, try one. Ask a friend with a telescope or get involved with your local astrono- my club. Peering through a few different models can help illuminate what you need Stephen Hawking, 1942 - 2018 in your own.
Some Upcoming Events at CIT Blackrock Castle Observatory
Summer Space Camp @BCO
Our 11th annual summer Space Camp is taking place over the following dates:
Week 1: July 9-13 | 9:30 – 12:30 | 5-7 years (4-year old’s cannot attend – children must have completed Junior Infants) Week 2: July 16-20 | 9:30 – 12:30 | 7-10 years Week 3: July 23-27 | 9:30 – 12:30 | 10-12 years Space Campers will take a journey down to another planet with our Eggstronauts and see what it takes to sur- vive the fall. They’ll put their scientific skills to the test, exploring what life might need and how we find it. The budding astronauts will have a blast! building and launching their own rockets and will learn about the pos- sible alien life that those rockets could find!
PUBLIC OPENING Hours: 10am—5pm (Mon-Sun)
Phone: +353-21-4326120 / Email: [email protected]
Blackrock Castle Observatory is operated by Cork Institute of Technology and is a partnership with Cork City Council.