* Astronomy

Blobrana · L

RE: July 2013

Blobrana · L

Highlights

The Summer Triangle-- Vega, Deneb, and Altair -- holds the central position, high in the south. The scorpion sits low to the south and slightly west. Directly to the arachnid's east is Sagittarius, the Archer, and between the two lies the direction toward the Milky Way galaxy's centre. The ribbon of soft light that delineates our galaxy flows up from the south, through the Triangle, and then cascades toward the northern horizon.

Trifid and Lagoon Nebulas

By mid-month the distinctive "Teapot" of Sagittarius should be hovering above the southern horizon.

Looking towards the right of the lid of the teapot and a little to the right is the delicate Trifid Nebula, "M20". A nebula is simply a cloud of interstellar dust and gas, the raw materials that stars are made of. If there are already stars embedded in the cloud it will glow with an eerie ghostlike appearance forming such vistas as the Great Orion Nebula, or this one, the Trifid. Sporting two patches of nebulosity, one red the other blue, this is one of the finest objects in the sky and very easy to find in binoculars. Just slightly below M20, is the rosy red Lagoon Nebula, which goes under the profoundly less romantic name of "M8". This is one of the best diffuse nebulas for naked eye observers, surrounding the small young star cluster NGC6530. The nebula is known for having a number small dark globules of material believed to be stars at the very beginning of formation, sometimes called protostars. Overall M8 is over 100 light years across, with its central regions a more modest 50 light years in diameter. It is also one of the largest in the sky, challenging the full moon for size.

M51 The Whirlpool Galaxy

Summer is the time for the galaxies.

As the earth swings around in its orbit the night skies are aimed away from the centre of our own galaxy, the Milky Way. No longer does the body of the Milky Way block the skies, now we can look out into the depths of space. One of the most spectacular is M51, better known as the Whirlpool Galaxy located right below the handle of the "Big Dipper". This was the first ever to be seen as in the classic spiral form, in the mid-19th century. While visible in the smallest instruments, its twisted nature will not show in anything less than an eight-inch telescope. With a luminosity of 10 billion suns and a diameter of 100,000 light years, M51 is roughly equivalent to M31, the great Andromeda galaxy and in turn, our own home. The Whirlpool is about 35 million light years away and glows at a genial eighth magnitude. In the sky it is seen face on and is about 1/3rd of the visual width of the Moon. It should be visible as a dim fuzzy patch in a pair of binoculars in a very dark sky. If you are lucky in that regard, step outside and see what you can see tonight.

Notable Messier objects

M3 is one of more heavily studied globular clusters due to its position in the galaxy, putting it far above the interstellar dust and gas that dim its light. More than 200 variable stars have been observed out of a total of near 50,000. Being one of the brightest

globulars, M3 is regarded as one of the most striking in the sky. A 60mm scope will begin to reveal hundreds of its magnitude 11 stars, while larger instruments may show arms or branches radiating from the sides.

M5: A Nice Globular Cluster

Located in the "head" half of the split constellation, Serpens, you will find the smashing globular cluster, M5. These are round, concentrated clusters of old stars which usually collect into halos surrounding galaxies. They contain between 100,000 to 10 million stars and are typically 100 light years across. Globulars are wonderful objects in small telescopes due to their perfectly rounded shape and the delicate glistening of the nucleus.

Omega Centauri in the southern skies is by far the best. northerners can relish M13 in Hercules, M3 and now M5, which are, considered one of the finest in the sky. It's 13 billion year age makes M5 one of the oldest clusters known. Easily visible in binoculars it takes at least a four-inch telescope to be able to resolve some of its ½ million stars.

Blobrana · L

Mercury: at magnitude -0.3, starts the month in the constellation of Gemini. The planet is in conjunction on the 9th and unobservable until the last week of the month. Mercury (1.3 mag) is close (1.1° separated) to Regulus on the 22nd. Mercury is at its Greatest Elongation (19.6° West) on the 30th.
(On July 24th, RA= 6h58m03s Dec=+19°16.2' (J2000) Distance=0.738AU Phase k=20% Diameter=9.1")

Venus: is at magnitude -3.9. The planet is in the evening skies in the constellation Cancer at the start of the month. It is best seen from 5.6h - 22.4h. Venus passes through the Beehive cluster on the 3rd. Venus is close to the star Regulas on the 22nd.
(On July 1st, RA= 8h27m17s Dec=+20°48.0' (J2000) Distance=1.502AU Phase k=90% Diameter=11.1")

Earth: The Earth-Moon barycentre is at Aphelion (distance to sun: 1.0167 AU) at 23.06.9 UT, 4th. The Earth reaches aphelion (its farthest point, 1.0167 AU, from the Sun) at 14:44.5 UT, 5th July.

The Moon: Full moon at 18:15.5 UT, 22nd July. Lunar perigee (distance 352032.4 km) at 20:29.2 UT, 21st July. Last Quarter Moon is at 17:43.4 UT 29th July. Lunar apogee (distance: 400104.6 km) is at 00:50.1 UT, 7th July. New Moon is at 07:14.3 UT, 8th July. First Quarter Moon at 03:18.3 UT, 16th July, 2013.

Mars: at magnitude 1.5 starts the month in the constellation Taurus. Martian northern Spring begins on the 31st.
(On July 1st, RA= 5h22m01s Dec=+23°32.4' (J2000) Distance=2.453AU Phase k=98% Diameter=3.8")

Jupiter: is in the constellation Gemini. At magnitude -1.9, the planet is observable low in the morning sky this month. Mars is 0.8° from Jupiter on the 22nd.

Transit times of the Great Red Spot are posted in a seprate thread.
(On July 1st, RA= 6h04m13s Dec=+23°13.4' (J2000) Distance=6.129AU Diameter=32.1")

Saturn: at magnitude 0.5 sits in the constellation Virgo. Saturn is about 0.5º from the star Kappa Virginis. The planet is stationary on the 8th. Saturn is about 3° from the Moon on the 17th. Saturn's rings are tilted ~17 degrees to our line of sight.
(On July 1st, RA=14h12m58s Dec=-10°42.8' (J2000) Distance=9.371AU Diameter=17.7")

Uranus: is in the constellation Pisces. Uranus at magnitude 5.8, has a bluish-green hue and appears 3.5 arcseconds wide. The planet is stationary on the 17th.
(On July 20th, RA= 0h46m27s Dec= +4°13.2' (J2000) Distance=19.759AU Diameter=3.5")

Neptune: is at magnitude 7.8 in the constellation Aquarius. The planet is best seen the morning sky.
()

Pluto: is in the constellation Sagittarius (mag 14.0). Normally, a finder chart is necessary to help in identifying the 0.13" diameter dwarf planet. The dwarf planet is at opposition on the 2nd July.
()

The Sun enters the zodiac sign of Leo at 15:56 UT on the 22nd July, 2013.