Tuesday, April 22, 2014

Planning Milky Way Photography

Milky Way over Mono Lake Tufa Rock Formations
By now most of us have seen stunning Milky Way shots, but when we go out at night in the Northern Hemisphere we find that the Milky Way is not prominent in the sky all of the time and the moon often interferes with its visibility as well.  The best nights and times are fairly easy to anticipate, so let's review them.

The Milky Way is like a big, flat disk, with a fatter portion in the center, much like flying saucers are depicted.  At least arms spiral out from the center, and our solar system is partway out on one of these arms.  So while the disk of the Milky Way which we're in looks like a stripe of stars across the sky, when we're looking towards the larger center of the disk containing more stars, it's brighter.  Due to the tilt of the earth's rotational axis, that bright center of the Milky Way is highest in the sky in the weeks around the Summer solstice.

As for best viewing conditions, the dark sky days around the New Moon are best, when the light of the stars in the Milky Way seem brightest and offer the greatest contrast against the dark sky background.  There is an added complication as the position of the Milky Way and constellations change nightly, moving east to west further each night, until the constellations end up in the same place in the sky at the same time the following year.  The constellations moving all the way around us in 12 months to return to the same place in the sky is similar to the movement they make in 24 hours, so to complete the trip around in a 12 month year, each month the constellations rise 24 divided by 12 = 2 hours earlier, 30 minutes per week.  So Whatever time the Milky Way rose above your horizon last week, it'll be 30 minutes earlier this week and 2 hours earlier on the following month.

Fortunately you don't have to make a bunch of observations and calculate future times, there are apps to do the work for you.  There are a number of stargazing programs out there for both interpreting the current sky and anticipating how it'll look at some date and time in the future.  I use StarWalk, which provided the following display last week as the April 15 lunar eclipse was ending:

When you see that trident-shaped pattern of Scorpius coming up along the east to southeastern horizon, you know that the bright galactic center of the Milky Way is not far behind.  It would have been 2 hours later, 2:45 am, to reach this position in the sky four weeks earlier.

Now let's look at other months.  Note the time changes in the upper right corner as we go from early May to late May, as the moon rises roughly 90 minutes earlier after three weeks pass:

As we jump forward to dates close to the new moon dates in late June, July and August, rise time is no longer an issue as the Milky Way is already in the sky once the sky gets dark enough to see it.  So June, July and August are the most convenient months to shoot it, since you won't have to wait long after sunset to start shooting.  There's a term astronomical twilight to describe when the sky is fully dark, and a program such as The Photographer's Ephemeris can tell you when that is, both at night after the sun sets to the west and in the morning as the sun approaches to the east.

You'll notice that the Milky Way starts the night a little more vertical or "tilted up" in the sky each month.  It's also a little further along the southeast to southwest path that the galactic center takes in the sky, so you can use that knowledge to plan specific compositions.  The Galactic center also starts a little lower in the sky as you get further form the Summer solstice.

So using the new moon dates each year and a program like StarWalk, you adjust the date and time to pre-visualize what the sky looks like and determine approximately how many compositions featuring your favorite natural or man-made landmarks will look.

For more information on how to shoot the Milky Way once it's in the sky in front of you, read my prior blog post: How to Take Milky Way Photos.

To take the concept even further, you can capture sequential photos of the Milky Way and convert them into a time-lapse video like this!

Friday, April 11, 2014

More Endangered Than Most

Desert tortoise populations have declined up to 90% in recent decades due to human activities such as housing developments, energy development and grazing. They spend up to 95% of their time in burrows, where they may get trapped or succumb to heat if the burrow collapses due to a vehicle or large animal. They like sandy soil, and when visiting sand dunes people can cause these collapses. The U.S. Fish and Wildlife Service manages endangered species, and many desert tortoises are on land administered by the Bureau of Land Management. A center was established by the BLM to care for desert tortoises, mainly surrendered pets.

In the last 2 days some many news reports have falsely implied that the BLM was euthanizing the protected wild tortoises. The misrepresentation of fact must be intentional, since the Desert Tortoise Conservation Center clarified the situation in a press release months ago:

 Aug 26, 2013
Statement Regarding Media Reports on Status of Desert Tortoise at the Desert Tortoise Conservation Center in Nevada

Recent media reports regarding the status of desert tortoises at the Desert Tortoise Conservation Center (DTCC) have implied that the FWS is currently euthanizing desert tortoises at the facility. We want the public to know that the FWS is not euthanizing healthy tortoises. 

The DTCC was established in 1990 to receive wild tortoises in harm’s way from development and has taken in unwanted pets since 1996. Over 1,000 tortoises arrived at the DTCC each year, and approximately 98 percent of those are surrendered or stray pets. Science-based protocols developed for desert tortoises brought to the DTCC have been instrumental in helping the FWS maintain a healthy population of desert tortoise in the wild. Managing to recover desert tortoise, a threatened species, is a complex task in which all options need to be considered, and all risks and benefits to the species must be assessed. 

Many pet tortoises, unfortunately, are diseased or otherwise in poor health, and run the risk of spreading disease to wild tortoises. These tortoises cannot be relocated to the wild, or otherwise contribute to recovery of the desert tortoise population. Sometimes euthanasia of unhealthy pet tortoises is necessary, but only as last resort, and only after we evaluate other options. All healthy tortoises at the DTCC will be relocated to sites that will support the recovery of the species. 

Progress is being made on translocating the healthy DTCC tortoise population to the wild. A Programmatic Environmental Assessment is complete, and tortoises are already being translocated by the FWS to an approved site in Trout Canyon, Nevada. Public scoping for a second translocation plan was completed Aug 22, 2013, for a proposed translocation area south of Coyote Springs, Nevada. 

The Animal Foundation (TAF), Lied Animal Shelter continues to take in unwanted pet tortoises from the public. However, the fact remains that the DTCC does not currently have the capacity or the funding to accept and care for additional tortoises. 

Recovery of the desert tortoise in the wild continues to be our top priority. However we are deeply concerned about the growing number of unwanted pets, and will continue to work with our partner agencies toward finding a suitable solution for tortoises that cannot be returned to the wild. Posted on August 26, 2013 https://www.change.org/petitions/stop-the-planned-killing-of-desert-tortoises/responses/8917

The factual misrepresentations are coming up in a story about a Nevada rancher Cliven Bundy who reportedly owes $1.1M in grazing fees to the BLM, and who following decades of debate over the issue in federal court has been issued court orders to remove his cattle and to not interfere with removal operations if he fails to remove them himself. The matter has gained national attention in recent days as people have flocked to the ranch to side with Bundy's resistance to the court orders. Various political scapegoats are trotted out by media outlets with an agenda to promote, and many of the protesters onsite now resisting federal authorities are reveling in repeating the misinformation. The incident could turn into quite a sideshow in the coming days. 
#bundyranch #deserttortoise #mojavedesert