One of the most fascinating aspects of the science of astronomy is the concept of distance. Everything in the night sky is so incredibly remote! Even the closest star to our solar system, the Alpha Centauri triple-star system, is 25 trillion miles away. The thousands of other stars that we see every clear night with the naked eye, as well as the millions of stars visible through telescopes and binoculars, are farther still! The Winter skies contain a huge range of objects. Have you ever noticed that the night sky in winter looks different than the summer? We see constellations at different times of the year – Spring, Summer, Autumn, & Winter. This occurs because the Earth is orbiting the Sun. In winter, we see the constellation Orion in the south at night and during the day the Sun is in the sky with the constellation Scorpius. In summer, we see the opposite (we see Scorpius at night and Orion is in the sky during the day). This is why you cannot see Orion or any one constellation all year long…There are 5 planets you can see with your own eyes! From Earth, we can see the five closest planets – Mercury, Venus, Mars, Jupiter, and Saturn. To your eyes they appear as stars. They do not create light like a star, rather sunlight illuminates their surfaces and we see them the same way we see our Moon, just not the same size. The Moon appears so large because it is close and the planets appear like dots or ‘stars’ because they are so far away.
The 5 planets were discovered before the invention of the telescope. Ancient people called these five planets ‘wanders’ because they appear to wander against the background of stars. This is due to the orbital movement of the planets. The word ‘planet’ comes from the Greek word ‘wander’. One good way to tell stars from planets is that looking at them with the unaided eye, stars twinkle and planets do not. The twinkling of stars, technically known as stellar scintillation, is caused by the Earth’s atmosphere. Because stars are so incredibly distant from us, any disturbances in the atmosphere will bounce around the light from a star in different directions. This causes the star’s image to change slightly in brightness and position, hence “twinkle”.
Mercury is the closest planet to the Sun making it the most challenging planet to observe. It is only visible during twilight – just before sunrise or just after sunset. The window for observing Mercury is measured in minutes. The best times to view the planet is when it is furthest from the Sun in the sky called greatest elongation. When Mercury is at greatest elongation it is visible for about an hour before sunrise or after sunset. Binoculars and telescopes are recommended for viewing Mercury. Because it is an inferior planet (between Earth and the Sun) it has a cycle of phases similar to what we see on the Moon. Look for Mercury in the west durng May – June 2015.
Venus is the brightest planet. In fact, it is the 3rd brightest object in our sky (after the Sun and Moon). Venus is often referred to as the ‘Morning or Evening Star’ as it is only visible during twilight – before sunrise or after sunset. Even thought it appears as a star to your unaided eye, it is a planet and the light is coming from the Sun. Because it is an inferior planet (between Earth and the Sun) it has a cycle of phases similar to what we see on the Moon. Binoculars or a telescope is needed to view the phases but appears asa featureless white object due to it covering of think reflective clouds. The brightest planet is spending the first part 2015 of this year unmistakingly dominating the west after sunset.
Planetary conjunctions are not uncommon events, as all the planets in our solar system race around the Sun like speed skaters, with those on the inside tracks catching up to and passing those on the outside. So, occasionally, a clustering of planets on the same side of the Sun will happen for short periods of time. Most conjunctions involve two, perhaps three planets; seeing six at one time is, indeed, a rare treat. For amateur sky-watchers, it’s a feast for the telescopic eye to have so many planets in one section of sky, and they all look different. Two club images below, First image by Barry Cahill from the December 2008 conjunction of the Moon, Venus and Jupiter, on this occasion the Moon actually covered (Occulted) Venus, the second image by Ronan Newman from 2005 with Venus next to Mercury.
A conjunction is also an opportunity to clearly see the ecliptic, the plane of our solar system. All of the planets extend out from the Sun’s equator, within a few degrees of each other, in a remarkably flat plane, like dust mites on the surface of a spinning CD. When you look at the cluster of planets in the sky, you can see how they all form a line running up at an angle from the horizon. Tilt your head to match that line and you are looking along the path we on Earth follow around the Sun every year.
Interesting upcoming Conjunctions in 2015-2016
October 17, 2015 Mars 24′ north of Jupiter
October 26, 2015 Venus 1°04′ south of Jupiter
November 3, 2015 Venus 42′ south of Mars
November 25, 2015 Mercury 2°46′ south of Saturn
January 9, 2016 Venus 5′ north of Saturn
May 13, 2016 Mercury 26′ south of Venus
July 16, 2016 Mercury 32′ north of Venus
August 25, 2016 Mars 4°23′ south of Saturn
August 27, 2016 Mercury 5°16′ south of Venus
August 27, 2016 Venus 4′ north of Jupiter
October 11, 2016 Mercury 52′ north of Jupiter
October 30, 2016 Venus 3°02′ south of Saturn
November 24, 2016 Mercury 3°28′ south of Saturn
For more info on the Naked eye planets see HERE
These are a wonderful set of satellites that I have watched over the past ten years. After Comet HALE BOPP and the formation of the Galway Club my interst in astronomy kick started again, after buying a telescope and spending many nights out observing I started noticing these extremely bright satellites, but these were no ordinary satellittes. The would be moving along and then all of a sudden energise in brightness to about 40 times that of Venus similar to a First Quarter Moon for several seconds and the fade away. A fantastic sight and whats even more amazing is that you can find out when and in what part of the sky to see them. You do not need to know the constellations just face the direction given, you can’t miss them. Also the lower the magnitude, the brighter. Usually -8 is the best we can see.
The Iridium communication satellites have a peculiar shape with three polished door-sized antennas, 120° apart and at 40° angles with the main bus. The forward antenna faces the direction the satellite is traveling.
Occasionally, an antenna reflects sunlight directly down at Earth, creating a predictable and quickly moving illuminated spot on the surface below of about 10 km diameter. To an observer this looks like a bright flash, or flare in the sky, with a duration of a few seconds.
Ranging up to -8 magnitude (rarely to a brilliant -9.5), some of the flares are so bright that they can be seen at daytime; but they are most impressive at night. This flashing has been some annoyance to astronomers, as the flares occasionally disturb observations and can damage sensitive equipment. When not flaring, the satellites are often visible crossing the night sky at a typical magnitude of 6, similar to a dim star.
VIEWING SATELLITE FLARES
Looking for satellites whilst skygazing, or satellite spotting, is a hobby for many people. While satellites may be seen by chance, there is a websites HERE which provide location specific information as to when and where in the sky a satellite flare may be seen.
The Naval Ocean Surveillance System (NOSS), is a series of SIGINT satellites which conducted Electronic signals intelligence for the U.S. Navy beginning in the early 1970s. The first series of satellites were codenamed White Cloud , while second and third-generation satellites have used the codenames Ranger and Intruder. The system is operated by the United States Navy and its main purpose was tactical geolocation of Soviet fleet assets during the Cold War. The NOSS satellites operate in clusters in low Earth orbit to detect radar and other electronic transmissions from ships at sea and are visible to the naked eye and have been seen many times over Ireland. See www.heavens-above.com for details of passes