24 November 2016

Geminid Meteor Shower 2016

Geminid Radiant in Gemini
Every year there are many meteor showers that arrive on schedule, resulting from the fact that Earth travels through well-established regions of dust and particles on its annual trek around the Sun. The Geminids are one of the year's best, reliably peaking as the Earth passes through the remants of asteroid 3200 Phaethon on December 13th and 14th each year.

One of the most important factors in viewing a meteor shower is to find a dark sky and this year, unforunately, this will be very difficult due to the fact that the full Moon coincides with the peak of the Geminids. So although many meteors will streak into the upper atmosphere and burn up, most won't be visible because their light will be drowned out by the glowing moonlight in our atmosphere.

That being said, if the weather is clear and you have warm clothing, it will be a fine night to just sit out in your garden or a park or on a mountainside and look anyhow. The Geminids reach their peak much earlier than most meteor showers, so a pleasant hour of viewing in the evening should reveal a few of the brighter meteors. Just temper your expectations and you will have a nice night. You won't see hundreds of meteors per hour, but then again, there will be plenty of stars and if you have binoculars, you can turn it into an evening of reacquaining yourself with the brighter stars and nebulae of the winter sky as Orion climbs high into the eastern sky after sunset and Pegasus dominates the sky overhead.

Here are excellent online resources for further reading on meteor showers:

Sky & Telescope

NASA

EarthSky

Image courtesy of Sky & Telescope.

11 November 2016

Supermoon on November 13 and 14

How much bigger is a Supermoon? 
The natural cycles of the cosmos brings us many interesting sights in the night sky and our closest celestial neighbor, the Moon, is always one of the best and brightest as it aligns with the Sun for an eclipse, or a planet for a spectacular conjunction. Sunday and Monday November 13 and 14, the Moon reaches its closest point on its orbit around the Earth at nearly the exact same time as it reaches its full phase, creating a Supermoon. This special situation happens every year or so, but this time the Moon will be a slight bit closer to the Earth, making this the closest Supermoon since 1948. The next Supermoon of this stature will arrive in 2034. So if you have clear skies Sunday or Monday, make a special effort to get out and see this ever-so-large object in the sky, 14% larger than it is when the Moon is at its farthest from the Earth.

The exact moment of the full Moon is Monday morning at 5:52 am pacific time, and the closest approach to the Earth (perigee) at 3:22 am, a bit earlier that night. So if you want to see the biggest and best view that will be early Monday morning November 14th. However, moonrise on both the evening of the 13th and 14th should be incredible so don't feel obligated to see it at the exact moment if you prefer sleeping in a warm bed! Or if you happen to live in Europe you can simply watch the moonrise on the evening of Monday 14th and you'll be all set. The exact time of moonrise can be found here, depending upon your location.

Here are some good online resources to learn more: 



Image courtesy of Wikipedia

10 November 2016

Three Planets in the Sunset Sky

Three planets are visible in the west just after sunset. Saturn is on a gradual fade into twilight and will disappear from view later this month, following the path of the zodiac constellation Sagittarius and the center of the Milky Way as the Earth's steady motion around the Sun carries us from the summer and fall constellations into the winter skies.

Mars, Venus, Saturn
Venus is the brightest object in the west for the coming months, maintaining its position as a bright beacon above the horizon for an hour or two after sunset. Both Venus and Mars are not 'pulled' into the western horizon in the same way as Saturn because they are much closer to the Earth and more nimble, moving steadily east in their orbits and keeping pace with the Earth's own motion. For that reason they remain in the evening sky after sunset with Venus eventually dropping out of sight late this winter and Mars holding its western location until nearly summer.

To see any of this you will need a clear and unobstructed western horizon. A pair of binoculars will enhance the view. And clear skies!

07 August 2016

Perseid Meteor Shower 2016

One of the finest meteor showers of the year, the Perseid Meteor Shower, arrives over a two day viewing window from 11 to 12 August. With a first quarter moon setting near or shortly after midnight, the Moon will provide some distraction during the evenings, but the dedicated meteor seeker will be rewarded with dark skies after midnight when meteor showers naturally reach their peak.

To see the Perseids (or any meteor shower, for that matter), you will be best served by a dark location away from streetlights and ideally away from city lights. If you are in a fully light polluted city and cannot get to a dark rooftop or garden, then your chances of seeing many meteors are poor. However, any step you can take to eliminate light will help, from switching off your own house lights to avoiding streetlights to traveling outside of a city to the beach, desert or mountains. Why? Meteors come in all shapes and sizes and during a meteor shower many of the meteors that sail into Earth's atmosphere produce only a brief, faint trail of heated gas in their wake. Some, of course, are large and visible for longer periods, cover a greater portion of the sky, and are so bright that you cannot miss them. So to improve your odds of seeing more meteors and increase your enjoyment, find a dark spot, bring a lawn chair or blankets so you have a good view of the sky overhead, and relax while the show unfolds. And be prepared to stay up late for the best viewing.

Meteors are also fickle in that they come in groups, sometimes with two or three brights ones in a minute, and then there might be 10 minutes in which you see none and you start to give up hope. But the Perseids will deliver so you just need to be patient.

Universe2go created a great infographic that I have attached to this blogpost. Click to enlarge or download and print. It's a good resource guide for the meteor shower.

19 June 2016

Summer Solstice 2016

The Summer Solstice is a special moment in the grand scheme of the Earth-Sun system, a date that represents a still-stand in the cycles that govern our universe. The solstice arrives on Monday 20th for the USA (Tuesday 21st for most of the rest of the world) when the north polar axis of Earth is tilted at its maximum toward the Sun. In addition to this being the longest day in the Northern Hemisphere for the entire year, there are other interesting effects.

The duration of the longest day in the Northern Hemisphere is a relative duration. In San Francisco, the length of the day on the Solstice is 14 hours 47 minutes, but that duration depends upon the latitude north of the Equator. The further north you are located, the longer the longest-day at Solstice. For example, in Seattle the Solstice day lasts 16 hours, and in Anchorage Alaska, the Solstice day lasts 19 hours 21 minutes, and in addition when you are that far north twilight never fully fades to dark and the sky remains in twilight glow the entire time the Sun is below the horizon. Of course, extreme situations emerge in locations such as the far northern reaches of Alaska, Canada, Greenland, Iceland, the Nordic Countries and Russia that lie above the Arctic Circle where the Sun is above the horizon for 24 hours on the day of the summer Solstice.

Solstice & Equinox
The term Solstice means 'Sun standing still' and refers to the perception from an Earth-bound point of view that the Sun appears to stand still in the sense of its gradual change in altitude on a daily basis. Of course, the Sun never stops moving from east to west each day, but the careful observer armed with a sundial would notice that the Sun, which has for six months been increasing in altitude at local noon each day, will appear to 'stand still' on the Solstice and gradually reverse course over the coming days, starting its six month downward trajectory toward Fall and Winter. The grand cycle of the Sun is of course attributed to the fact that the Earth is tilted on its axis and from a fixed spot on Earth, we perceive the Sun's changing altitude in a graceful cycle that slows and stops and reverses course each Solstice, and reaches a peak transition during the Equinoxes. The image shows this nicely.

This year's Solstice also features a Full Moon, so enjoy the shortest night with a bright and shiny Moon to accompany you.

This excellent article in Sky & Telescope provides further illumination on the subject.

Image courtesy Sky & Telescope.

27 May 2016

Mars at Opposition

Mars at Opposition
Mars just reached opposition, a time when it is in a straight line with the Earth and Sun. Mars therefore rises at sunset and is visible all night. It is also at its brightest, because usually opposition is also when the planet is at its closest approach to Earth and is fully illuminated, like a Full Moon.

Mars is presently located in Scorpius and as viewed from Earth is going through 'retrograde motion' in which the steady westward movement of the planet is temporarily interrupted by a reversal in motion back toward the east, as the Earth speeds past Mars in its orbit. The path of Mars in the background stars is nicely captured in this image from Naked Eye Planets and shows the retrograde path of Mars quite clearly.

Mars is easy to spot, a bright orange dot in the south that is grouped near another bright orange-red dot (in this case, Antares, the brightest star in Scorpius), and contrasting with a yellow-white dot that is Saturn.

Image courtesy Sky & Telescope

25 April 2016

Moon, Mars and Saturn

Mars, Moon and Saturn
Mars and Saturn are moving toward opposition (in May and June, respectively), which means they are going to be rising earlier and be more visible in the evening sky, and will be brightening over the weeks ahead. These planets are in Scorpius and Ophiuchus, low in the south in the latter part of the evening through the early morning hours.

The waning Moon passes through this region over the nights of 24-25-26 April and should be a nice picture mixed with orange Mars, yellow Saturn, and the red giant star Antares in Scorpius.

Hope you can spot these two gems and the Moon as they line up for a few days, making the sky that much more interesting to see.

Image courtesy of Sky & Telescope.

10 April 2016

Moon to Occult Aldebaran

Moon Occulting a Star
Astronomical alignments are special events, times when the motions of the Earth and the rest of the cosmos brings about a particularly interesting juxtaposition of objects in the sky. Today (Sunday 10 April) the waxing crescent Moon will align itself with the bright star Aldebaran, covering it completely for observers in various parts of North America. See this article from Sky & Telescope for a detailed overview of the cities and the exact timing for disappearance and reappearance of Aldebaran.

The Moon sweeps around the entire night sky and touches each constellation of the Zodiac every month, passing in front of hundreds of naked-eye visible stars during its journey. But it is very uncommon for the Moon to pass in front of the brightest stars in the night sky. Aldebaran is a 'first magnitude' star, one of only 22 stars that are at magnitude 1 or brighter (and only four of these are close enough to the Ecliptic to be ever occulted by the Moon: Aldebaran, Antares, Spica and Regulus)
. For that reason the covering and uncovering of a star like this is a dramatic event, worth taking a few minutes with binoculars or a telescope to watch the proper motion of the Moon as a vastly more distant star's light is interrupted by the surface on the edge of the Moon and the light twinkles and vanishes from view for an hour.

On the west coast, the event takes place in broad daylight, but that should not make it any less impressive. Disappearance is at 2:21 pm and reappearance at about 3:40 pm. Check the Sky & Telescope article for more precise timings from around North America.