25 December 2014

The "Zero G Day" Hoax

Fake tweet
I enjoy the occasional science hoax, and the resurgence of the "Zero G Day" hoax brings a smile to my face. It is a claim that on January 4th, 2015 at 9:47 PST, gravity on Earth will be momentarily diminished due to an alignment of Pluto and Jupiter. There is just enough science in the claim to make many believe it could be true, but in fact it's far from the truth, just a fun prank started by the astronomer Patrick Moore years ago. Nonetheless, if thousands of people jump at that moment, we can test out the theory that the Earth might move if everyone jumped at once, a scientific idea explored well by the science video series from Vsauce.

I like this hoax almost as much as the "Mars will be bigger than the Full Moon" hoax that surfaces every year. It's getting harder to separate fact from fiction in our socially-networked world. I look to Slate's Phil Plait and his Bad Astronomy blog for this, along with snopes.com.

23 December 2014

Moon and Mars

Moon and Mars
The lunar month starts with the slim crescent Moon glowing in the western sky, sweeping past the bright orange beacon of Mars and the faint stars of Capricornus. Venus is just starting to appear in the west after sunset, so if you have a clear view of the western horizon, look for it shortly after sunset. It will soon be higher and easier to spot as 2014 comes to an end.

Image courtesy Sky & Telescope.

26 November 2014

Lunar Month Begins

Lunar Month Begins
Thanksgiving in the USA is accompanied by a young Moon,  a few days into the lunar cycle and the new lunar month. I enjoy the changing face of our nearest neighbor in the Solar System, a lovely sight early in its cycle. This week we'll see the Moon pass near Mars and then wander through the faint constellation Capricorn, en route to encounters with Neptune and Uranus. The San Francisco Bay Area is being graced with clear, crisp November nights so when the Sun sets after your Thanksgiving dinner, step outside and enjoy the view to the west, and a few hours later you'll also see the spectacular bright stars and constellations of winter rising in the east.

Image courtesy Sky & Telescope.

15 November 2014

Leonid Meteor Shower 2014

I enjoy the annual Leonids meteor shower for many reasons, not the least of which is that it is my birthday meteor shower, peaking on my birthday each year. The peak of the Leonids comes on the evening of November 17 into the early morning hours of November 18, and this year the Moon is a thin waning crescent in the early morning and won't disrupt the viewing of meteors. So, get a warm blanket and a clear view of the sky and enjoy this annual shower that promises

Leonid 'Radiant'
Like all meteor showers, they are caused by a remnant of a celestial object, most often a comet or asteroid that leaves a wake of particles that intercept the Earth's atmosphere on a predictable annual basis. The Leonids are caused by Comet Temple-Tuttle that orbits the Sun every 33 years. The debris stream from Temple-Tuttle is littered with sand-like particles that glow and shine in the upper atmosphere when they strike it at thousands of miles per hour, creating the beautiful 'shower' of light. Under dark skies you can see 10-20 Leonids per hour, so set your expectations appropriately and be patient. You can't hurry a meteor shower - let it come to you and present itself in all its splendor. This year Jupiter adds to the mix, now in a location near the center of Leo and therefore near the 'radiant' of the shower. Here's to clear skies and good viewing.

Here are more detailed write-ups. I found the Sky & Telescope article to be quite informative.



Image courtesy of Sky & Telescope.

08 November 2014

Shiny Pre-Dawn Sky

The Moon and Jupiter
Mornings are splendid this time of year, with plenty of darkness to make it easy to see the sky when you first get up, and so much to look at right now. Jupiter shines brightly high in the eastern and southern sky before sunrise, and all of the magnificent winter constellations dominate the sky to the south and above, glimmering in the quiet of the early morning. I savor the moments when I am up early and have a few minutes to take in the spectacle, starting my day on a good note.

Over the coming week, the waning Moon graces the southern and eastern skies and passes near Jupiter on the 14th.

Image courtesy of Sky & Telescope.

31 October 2014

Amazing Sunset and Sunrise Colors

Every sunrise and sunset provides a wide range of visual effects, ranging from the elongation of the disk of the Sun as it hugs the horizon, to the amazing range of colors you see in the minutes before and after the Sun’s passage through the horizon. One of my favorite effects is the curious coloration of the opposite horizon from the sunrise or sunset where one sees a colorful and rapidly changing band of sky called the Belt of Venus.

Belt of Venus at 35,000 Feet
Despite the name, the effect does not have anything to do with Venus the planet. Rather, the effect is due entirely to the shadow cast by the Earth into space, and our perception of that shadow as we observe the horizon from our vantage point along the Earth’s terminator. As we gradually rotate out of the darkness of night (at sunrise) or into the darkness (at sunset), we have a short-term view into the shadow of Earth which occupies the opposite horizon from the Sun. The colors are quite vivid with dark blue low along the horizon, and the refracted colors of the sunrise or sunset above that, creating a layered effect of blue and pink.

Belt of Venus on SF Bay
The images to the left and right show two interesting views I had of the Belt of Venus over the past many months. The first one was taken from 35,000 feet above the United States where I had the very unique vantage point of looking sideways into the sunset belt from high altitude rather than seeing it from sea level. I still cannot figure out why there is a white glow below the belt itself. The second image was taken from the Exploratorium in San Francisco, looking east after sunset toward Treasure Island and the Bay Bridge. The colors and pattern on the horizon were to be expected, but the rays of dark and light blue extending up into the sky were not. Here in this situation, I still cannot figure out the atmospheric phenomenon that would cause such an unusual ray of dark blue to extend upward into the sky. But in both cases the interplay of color and light was indeed remarkable and although pictures from an iPhone camera cannot do justice to the magnificence of the real thing, it’s something I felt compelled to document and write about.

So next time you are watching an amazing sunrise or sunset, be sure to turn around and take in the drama on the other horizon, or you will have missed out on some of the most beautiful parts of the sky.

04 October 2014

The Next Blood Moon: October 8, 2014

Total Lunar Eclipse of October 8th
We're in for the second of four total lunar eclipses in 2014-2015. Next week the Full Moon slips into the shadow of the Earth and reveals itself as a 'blood moon' in the early morning sky of Wednesday October 8th. You'll need to be up in the wee hours of the night, as the eclipse reaches total phase at 3:25 am pacific time, where it will remain in total eclipse for an hour. Given our good weather in San Francisco, this should be nicely on display and the view from the west coast should be nice, if you can get out to the beach. The Moon itself will not be a 'super moon' but will be larger than most Full Moons, so it should be an awesome sight.

You can find more details on the Sky & Telescope website. You'll need clear skies and a good view of the sky to the southwest. It should be a dramatic blood-red color, as the Moon will move deep into the umbral shadow of the Earth.

This infographic from Guy-AndrĂ© Pierre-Nicolas of astroshop.eu is an excellent resource that illustrates beautifully many facets of a lunar eclipse.

Image courtesy of Sky & Telescope.

24 September 2014

Red 'Stars' and White Moon

Slender Moon, Mars and more
For the next week, the twilight sky will feature a close alignment of two bright shiny red objects, Mars and Antares, and the slender Moon wending its way through the southwestern sky. The Moon encounters the ringed planet Saturn on Saturday 27th and then brackets the close pairing of orange-red Mars and the red supergiant star Antares in the constellation Scorpius. This first lunar cycle of autumn should start out beautifully with the waxing Moon and some lovely alignments. Look south and west shortly after sunset each evening for the best viewing.

Image courtesy Sky & Telescope.

10 September 2014

Luxury Star Gazing

Ritz Carlton Half Moon Bay
Fall in the San Francisco Bay Area means clear skies and mild temperatures, and clear skies along the coast - a welcome change after the fog of summer. If you are in the Bay Area in the coming months, stop by the Ritz Carlton Hotel and Resort in Half Moon Bay for a Friday night star party. I am running star parties there a couple Fridays per month and love the setting, the reasonably dark skies, and the fun interaction with guests from all around the world. The patio is located on a stunningly beautiful stretch of California coast next to the 18th green of the Ocean Course. Hope you can make it. Click here for the schedule and more information.

02 September 2014

Celebrate the Moon - Saturday September 6th

This Saturday is International Observe The Moon Night. Where will you be for this special evening? I'll be conducting sidewalk astronomy in front of the Exploratorium in San Francisco along with other astronomy enthusiasts. The Moon will be a few days away from another Supermoon, and if the skies cooperate, we should have a lovely view of Earth's natural satellite in gibbous phase between first quarter and full. Click the link for more information on International Observe The Moon Night. Hope to see you at an event.

22 August 2014

KFOG Broadcast - August 12, 2014

I paid a visit to the KFOG Morning Show and had a fun chat with Renee about the Supermoon, Perseid Meteor Shower, How to Look At The Night Sky, and Star Parties in and around San Francisco. Click here to listen

14 August 2014

Jupiter & Venus Conjunction – Closest Approach Since 2000

After the Moon, the two brightest objects in the night sky are the planets Venus and Jupiter. Venus is a close neighbor and a very reflective planet, dominating morning and evening skies with its brilliant white shimmer against the changing colors of the dawn or dusk sky. Jupiter is the giant planet of the Solar System and despite its distance, is a bold and bright object for us to enjoy, especially in a telescope or binoculars.

Venus & Jupiter Conjunction
These two planets, like all of the objects in the Solar System, gradually change their position with respect to the background stars from day to day. All of the objects in the Solar System move along a common path across the sky, the Ecliptic. And from time to time these objects line up and create beautiful patterns and visually stunning sights.

On the morning of Monday August 18th (from North America), we will see Venus and Jupiter in a conjunction, a close alignment of the two bodies from our Earthbound point of view. The two will be in the east just before sunrise, so you’ll have to get up early to see this, but it will be rewarding. The two will be less than the Moon’s width apart, and given their bright nature, the pairing should be spectacular. Through binoculars, you will also be able to see a lovely star cluster, the Beehive Cluster, in the background of stars, as Jupiter and Venus will be in the constellation Cancer and passing through the Beehive.

The image (courtesy of Sky & Telescope) shows where to look. From San Francisco, sunrise will be at 6:30 am and the Venus-Jupiter pair will rise at 5:00 am, so you will need a good northeastern horizon to see the pairing, and the 30 minute window starting at 5:00 will provide the best dark-sky viewing conditions as the glare of dawn will start to interfere by 5:30.

You can find an excellent write up on the conjunction on Sky & Telescope's website. 

10 August 2014

Perseid Meteor Shower 2014 - what to expect

This year’s Perseid Meteor Shower will peak on August 11-12-13 and should offer up a moderately pleasing view of meteors but will be impacted by the nearly Full Moon. Meteors come in all sizes and shapes and during a reliable shower like the Perseids, you can see them all. However, moonlight increases the ambient lighting of the entire night sky and consequently makes the faint meteors all but invisible. The medium-strength meteors and the fireballs will shine through the glare of course, so the Perseids will have a showing, but just not at the rate we often see during a truly dark sky shower.

Perseid Meteor
I’ve often written that meteor showers are best viewed after midnight, when we are turned toward the path of Earth’s orbit (we are on the “front-face of Earth” after midnight), and we get better meteors. This still holds true, but in a recent article in Sky & Telescope, author Alan MacRobert suggests that early evening is a very good time to look for earth-grazers, meteors that enter the Earth’s atmosphere as a low angle and can be seen for much longer periods of time.  I will certainly be looking for these. I’m not an all-night observer and prefer looking out into the sky waiting for meteors when I am a bit more awake. So the idea of seeing grazers carries appeal for me in more ways than one. Last week on Mt. Tam we witnessed some spectacular meteors, one of which had a trajectory that suggested it was an early Perseid grazer.

For more information on the Perseids, check out these resources.

Image courtesy of Stefano De Rosa 

07 August 2014

August 2014 Supermoon

Moon at Apogee and Perigee
We are in the midst of a three-month period of Supermoons, a confluence of orbital nodes that brings us the Full Moon phase at the same time as Perigee, the closest approach of the Moon to the Earth. The next one is on August 10. The difference in the Moon's distance from the Earth from Perigee to Apogee is quite substantial, varying from 222,000 miles out to 253,000 miles, leading to the a 14% difference in the apparent size of the Moon. In addition, the Moon will be at the peak of the ascending node of its orbit, placing it somewhat higher in the sky than is typical for summer Full Moons.

There will be an earth-bound effect in the king tides that will result from the Supermoon and other factors. Here's my write-up about the impact on tides and the significant ebb tides we can expect this weekend.

Image courtesy of Wikipedia.

31 July 2014

August Opens With an Evening Show

Evening Show
The waning crescent Moon creates a majestic skyscape to open the month of August, shimmering against the dusk sky with the shiny colors of Spica, Mars and Saturn in the path. Each evening the trio of planets and stars will have the Moon in their midst, and the Moon will slip gradually eastward with each successive night.

I enjoy seeing the waxing Moon with its delicate shape and edge-on illumination from the Sun. It's fun to see in a telescope and it always holds the promise of the gentle glow of Earthshine. In the middle of summer, the ecliptic is low on the southern horizon and the Moon slices a gradual slope across the sky.

This view will be enhanced by binoculars, if you have them. You will see deeper into the details of the Moon and into the constellations along the southern horizon with the fringes of the Milky Way in view due south as darkness falls.

Image courtesy of Sky & Telescope.

30 July 2014

Sun and Moon and Ebb Tides

A kayaking friend of mine referred me to a question posed by a fellow kayaker regarding tides in and around the Golden Gate: Why are Ebb Tides strongest in SF Bay at night during the summer and during the day in winter? I love this kind of question, where the celestial mechanics of the Solar System impact the daily experiences of hobbyists and average people on Earth. 

First of all, why are there differences in size of high & low tides throughout the month and year? Each month the highest highs and lowest lows occur when the Moon is Full or New. That’s pretty simple. But there are two important factors regarding the Moon’s proximity to Earth on any given Full or New Moon. And there is one important factor regarding the Sun’s proximity to Earth on any given Full or New moon.

1. The Sun’s Changing Proximity

The Earth’s orbit around the Sun is elliptical, meaning that there is a close approach each year on January 4th (“perihelion”) and a corresponding far point in our orbit in July (“aphelion”). The New and Full Moon phases just before or after January 4th have higher high tides at the noontime tide, leading to a very fine ebb tide in the middle of the afternoon.

2. The Moon’s Changing Proximity

The Moon’s orbit around the Earth is elliptical, so there are times when the Moon is closer (“perigee”) and farther (“apogee”). Lately the press has made much to do about the “Super Moons” that occur when the Full Moon lines up with Perigee. On August 10, 2014 we will have a very fine Super Moon precisely at the same time as Perigee, so there will be higher high tides at midnight and lower low tides at dawn, leading to a very fine ebb tide in the middle of the night.

Another factor is the Moon’s location along its orbit from a north-and-south perspective. The Moon’s orbit around the Earth is inclined slightly and follows the “ecliptic” which also meanders above and below the plane of the equator, meaning that sometimes it is physically above the plane of Earth’s equator and sometimes below (“ascending and descending nodes” of the lunar orbit). If the Moon is above the plane of the equator, it is actually a bit closer to the land and water north of the equator, exerting a slightly greater tidal pull. The next peak of this effect is on August 9, 2014, so we can look forward to some amazing high and low tides at the next Super Moon. The ascending node and its impact are not tied directly to winter or summer, so this effect is less predictable.

- - - - - - - - - -

To answer the original question: there are good ebb tides each month at New and Full Moon, but the changing effects of perihelion and perigee cause the solar influence to be greater in Winter (hence the better daytime ebb tides) and the lunar influence to be greater in Summer (hence the better nighttime ebb tides).

This website offers additional insights into tides. 

Fun subject to think about! Wow!

20 July 2014

Binocular Astronomy

From an urban setting such as my home in San Francisco, I have a reasonable view of the night sky, knowing that from my own backyard I can see a good number of stars if I have clear skies and I am patient, allowing my eyes to dark adapt. In a city setting you are limited in the depth of the night sky you can experience by the ambient light in your exact setting, and the light pollution dispersed into the sky. But you can overcome these factors somewhat, by using binoculars.

Every time I am at a star party or astronomy gathering, in addition to a telescope I bring my binoculars. These are the fastest way to enhance your viewing whether you are in a dark sky or city setting. No matter what conditions you have, you will see deeper and will experience more richness in the night sky with binoculars. They are intuitive and require no special technical knowledge to use. You just point at a part of the sky and enjoy. Gary Seronik of Sky & Telescope publishes regular articles focused on binocular viewing and has an excellent resource book (I have a copy, of course) just for binocular viewing, Binocular Highlights. I highly recommend it.

Summer Milky Way in binoculars
During the summer months, point east and above to experience the richness of the Milky Way through binoculars. Even in city settings where the true outline of the Milky Way is not visible, binoculars will reveal some of that richness, exposing clusters and nebulae in the depths of the galaxy. I am particularly fond of the charts from the Great Smoky Mountain Astronomical Association for highlights in the summer galactic zone.

My old Celestron 10x50 binoculars have served me well for years and I carry them with me virtually everywhere I go. You should consider the same.

Image courtesy garyseronik.com.

14 July 2014

Mars and Spica Align

Mars and Spica Align
I've been watching Mars over the past few months as it slips steadily along the Ecliptic. It was near the bright star Spica several months ago as it was near opposition, then moved retrograde toward Porrima on the other side of the constellation Virgo, and now is back near Spica as it resumes prograde motion toward an August rendezvous with Saturn. The image shows where to spot the two bright objects in the south-west sky this week.

Image courtesy of Sky Safari.

26 June 2014

The Start of a Lunar Cycle

Young Moon movements
Each time a lunar cycle begins, I look forward to each evening to see where the Moon is going to be, starting with a dark night sky at New Moon, and over the course of a week enjoying the waxing crescent of our celestial neighbor as it grows into First Quarter. Along this journey, I await alignments and close encounters, and in the early days of the current lunar cycle there are many objects in the path of the Moon.

Moon & Mars
New Moon is on Friday June 27th, and the first chance to spot the young Moon is Saturday 28th (which, if sighted, will start the month of Ramadan). The Moon on the 28th is very near Jupiter and both set shortly after sunset. It will pass very near Regulus in Leo on July 1st, and as it then travels across the ecliptic it will reach First Quarter and have a close encounter with Mars and Spica, covering Mars for a short while on July 5th, but this event will not be visible from North America.

After passing by Mars, the Moon will gradually move next to Saturn. More on that in my next blog post.

Images courtesy of Sky  & Telescope.

10 June 2014

Why You Should See An Eclipse

Shadows during an eclipse
I gave a talk recently at an event in San Francisco called Ignite, a fun evening of short, fast-paced talks on a wide variety of subjects. Click here to watch my 5 minute video on the subject of eclipses. I think you'll be inspired (and if not, then it's only 5 minutes :-)

30 May 2014

The Constellation Virgo

Late spring and summer skies are dominated by the big constellation Virgo, the Maiden. This grouping of stars is the second largest in the night sky (after Hydra), and includes the first magnitude star Spica, the double star system Porrima, and the Virgo Cluster, a region of the universe that has 1000s of galaxies in one place. [More on the Virgo Cluster and Supercluster in a future post]

The Constellation Virgo
A member of the 12-constellation zodiac, Virgo is directly in the path of the Moon, Sun and planets and consequently is host to wandering celestial objects. Now and for the coming months, bright orange Mars is passing through the constellation en route to a mid-July rendezvous with Spica. In mythology, the constellation represents a woman in the sky, but the identity is different depending on whether you read the Babylonian, Roman or Greek interpretation. And in any case, I find it quite difficult to see a distinctive pattern from the stars in Virgo. Nonetheless, it is a fascinating place in the sky, because it contains the Virgo Cluster of galaxies with notable telescope objects such as M86 and M87 and the magnificent Sombrero Galaxy.

Virgo occupies an interesting space in the sky, the First Point of Libra, a place where the Ecliptic (path of the planets and Moon) crosses the Celestial Equator (dividing line between the northern and southern hemispheres in the heavens). The Sun's arrival at the First Point of Libra marks the first day of Autumn in the northern hemisphere (Autumnal Equinox). The reason why this spot is called the First Point of Libra is that thousands of years ago the intersection of the Ecliptic and Celestial Equator was in the constellation Libra, but the effects of precession have moved that point from Libra to Virgo, and in 400 years that will move into the next zodiac constellation, Leo.

From city limits you can certainly find Spica, Porrima and for the next few months, brilliant orange Mars in Virgo. With binoculars you can gaze into the heart of the Virgo Cluster and although you won't see The Big Picture with 1000s of galaxies, you will certainly see a richness of stars and know that you are seeing light that is at the center of our own supercluster of galaxies that define our corner of the universe.

Images courtesy of Wikimedia Commons

22 May 2014

Possible New Meteor Shower

Meteors are a delight to see in the night sky, appearing without warning and gracing the sky with their shimmer and speed, playful fireworks that quietly captivate those who take the time to watch. Annually there are many meteor showers that we can predict and prepare for, primarily because they are caused by debris in the path of Earth's orbit and are reliably there each time Earth passes through the debris. In most cases "debris" means the small particles of dust no larger than a grain of sand, left in the wake of a comet or asteroid.

Radiant in Camelopardalis
Friday night May 23 through Saturday morning May 24, Earth will travel through such a stream for the first time from a source that we have not encountered before. In this case it's Comet 209P/LINEAR, a fairly unimpressive comet from a visual point of view, but one that has left a debris stream in its wake and could be have initiated a new meteor shower. The peak for this will be Friday night / Saturday morning around 1:00 am pacific time, so find a dark spot with a clear sky, give your eyes time to adapt, and enjoy. You don't need a telescope or binoculars. The 'radiant' point of the shower is in the faint constellation Camelopardalis (see image) but you don't need to face that way - just have a clear sky and a good view overhead, a lawn chair or pad to relax on.

More information on the following sites:

Sky & Telescope

Image courtesy of Sky & Telescope.