Mojave National Preserve Fall Star Party, Nov. 11th 2017

This fall’s Mojave National Preserve Star party is on Saturday November 11th, 2017. Make a weekend of it and come out earlier in the day to get some hiking in before the potluck meal Saturday evening. This is a good location for seeing desert tortoises, hares and there’s usually a few cows hanging around as well!

I saw this desert tortoise on the road to the campground in September of this year.
Desert hares are also pretty common around the campsite.
A few cows are still allowed to graze in the preserve.

The Mojave National Preserve is one of the darkest sky locations in Southern California and well worth a visit and we bring a good selection of telescopes to the star party.

Some of the telescopes at the last MNP Star Party. The covered eating/cooking area with benches and tables can be seen in the background.

This star party there will be a third quarter moon but it will not affect our dark skies as it doesn’t rise until 12:44 am. If you plan on attending please RSVP either on the  Event Facebook page or by Email.  The photo above was taken at the Spring 2017 star party. Hope to see you there.

Mojave National Preserve Star Party, Nov. 5th 2016

This fall’s Mojave National Preserve Star party on Saturday November 5th, 2016 at the Black Rock Canyon group campground will also be a party celebrating the 100th anniversary of the National Park Service. Come out early and get some hiking in before the potluck meal Saturday evening. The Mojave National Preserve is one of the darkest sky locations in Southern California and well worth a visit. This star party there will be a first quarter moon early in the evening until 9:45 pm so we get to see both a beautiful moon and then wonderful dark skies. If you plan on attending please RSVP either on the  Event Facebook page or by Email.  The photo above was taken at a prior star party. Hope to see you on Nov. 5th.

Mojave National Preserve Star Party

As the opening post in resurrecting this blog I’d like to announce the Mojave National Preserve Star Party is scheduled for Saturday 26th October. This is a wonderful star party in one of the few truly dark sky locations left in Southern California. The banner photo for this blog was taken at that location. The star party is held in conjunction with the Mojave National Preserve Service Project. In the evening before dark there is a communal pot luck dinner before the star party gets under way. Free camping is provided  for Friday and Saturday night at the Black Canyon Group Site across the road from The Hole in the Wall Campground. It can be windy at this location and it could be hot or cold at this time of year so prepare appropriately.

Desert Tortoise

When you get there keep your eyes open during the day for the threatened Mojave desert tortoise, I’ve seen quite a few in the area over the years. It is unlawful to touch, harm, harass or collect wild desert tortoises so eyes and cameras only – if you alarm the tortoise it may loose water that it needs for survival so keep your distance!

As I type this I am assuming that the current government shutdown will end before October 26th otherwise the star party will have to be postponed or cancelled. Many of my friends and colleagues including Mojave National Preserve Rangers are furloughed while people in Washington posture over an artificially created crisis designed to make themselves look important!

Star Party has been postponed until November 30th – see you then

New Jupiter Impact

Earlier today Australian astronomer Anthony Wesley reported a new impact site on Jupiter just as the sun was rising at his location. His image can be seen on his webpage. The time stamp on the image is Universal Time (UT). Renowned amateur observer Christopher Go has also captured a short video of the event which can be viewed on his site. There has not yet been a confirmation that there are leftover signs of the impact but observers are gearing up to try. To do this we need to know when the impact site is visible, according to Christopher Go the event occured at longitude 343 (System II). With this information we can calculate future observation opportunities:

6/4 5:04 15:00
6/5 0:56 10:52 20:47
6/6 6:43 16:39
6/7 2:35 12:30

All of the times in the table are transit times (UT). Practically the impact site is visible for a couple of hours on either side of the listed times. Unfortunately this does not work out well for viewing from my location in California – the time here is UT-7 hours so this gives the following local times for the transit:

6/3 10:04pm
6/4 8:00am 5:56pm
6/5 3:52am 1:47pm 11:43pm
6/6 9:39am 7:35pm
6/7 5:30am

The first opportunity at 10:04pm tonight (6/3) will not work because although the event is facing us Jupiter does not rise until 2 am and so is below the horizon! The following morning (6/4) the impact site will be visible from ~6am onwards and Jupiter will be high in the sky but the sun will have risen and be too bright. The first real chance is not until the morning of 6/5 from ~2am onwards as Jupiter is rising. This may be too long after the event for anything to continue to be visible.

Sky Fever

For various reasons it’s been too long since I was out observing under a good dark sky. John Masefield’s poem “Sea Fever” came to mind and so without further ado, my butchered version:

Sky Fever
I must go out to the dark sky, to the Milky Way in the sky,
And all I ask is a tall ‘scope and a star to steer her by,
With observers lists and a red light and coffee by the pint,
For a long night at the eyepiece until the grey dawn breaking.
I must go out to the dark sky, for the call of the nebulae
Is a wild call and a clear call that may not be denied;
And all I ask is an inky night with the deep sky calling,
And the dark lanes and the bright stars, and the clusters gleaming.
I must go out to the dark sky, to the vagrant observers life,
To the snake’s home and the coyote’s home where the day sun’s like an oven;
And all I ask is a merry yarn from a laughing fellow-rover,
And quiet sleep and a sweet dream when the long nights over.

With Apologies to John Masefield

Station Fire Moon

Over the last few days thousands of photos of the Station fire have been posted on the internet by many people. I have myself posted photos to Facebook of the fire that burned behind JPL on Friday night and some of these have been picked up and reposted elsewhere by others.

Astronomers have been hearing about the imminent danger that Mt. Wilson has been in and every night for the past few nights I have periodically stepped outside into my back yard and peered up to see if the antenna towers are still visible. Usually the peak has been swathed in clouds of smoke completely invisible from Pasadena but tonight when I stepped out they were still visible. The moon, shown in the photo I took this evening, was also up and is a bright orange, typically only seen during an eclipse and referred to as a blood moon by some cultures. These days we know that the orange colour we see tonight is due to light scattering from the large amounts of smoke and ash in the atmosphere that have been catching at our throats for the past few days but historically a blood moon was thought to foretell coming disaster and destruction.

Tonight is expected to be the night when the fire will make it’s assault on the historic observatory on Mt. Wilson. The weather today has been much better for fighting the fire and the defences on Mt. Wilson have been buttressed as much as possible during the day. A good account of the measures taken can be found on the Los Angeles Time L.A. Now blog. However as I look up at the mountain and then at tonight’s blood moon I can’t help but shiver. On this night our hopes and prayers are with the fire fighters that have remained on the mountain overnight to defend our history.

Mars Hoax

It’s the time of year when the ‘Mars as big as the moon’ hoax will be doing the rounds. The Old Town Sidewalk Astronomers have been combating this myth since 2005. The composite image above has two images of Mars pasted to the left of the moon – the images were taken by myself and are at the same scale. The large image is the size Mars was during it’s close approach to Earth in August 2003. The small image is the size Mars was in June/July of this year – a close approach occurs every 15-17 years. Mars is never any bigger than it is shown here ie it is never the size of the moon.

There is more information about Mars and the Mars hoax on the Old Town Astronomers website

Jupiter Impact Update

The Old Town Sidewalk Astronomers had some excellent views of Jupiter Saturday night through my 8 in SCT and Jane’s 7 in refractor. The impact site was clearly distinguishable and we watched it rotate across the disk. We finished the evening with a quick look at the other blue planet, Neptune.

I’ve had a number of requests about future times for viewing the impact site. Here are the best transit times from tonight onwards for Pacific Summer Time – remember the site is visible for about 1 1/2 hours either side of these times.

7/28/2009 1:33 AM
7/30/2009 3:11 AM and 11:03 PM
8/1/2009 4:49 AM
8/2/2009 0:40 AM
8/4/2009 2:18 AM and 10:10 PM
8/6/2009 3:56 AM and 11:48 PM

All times calculated using the excellent Astromist application for PDAs available from

Viewing Jupiter’s Impact Site

So you want to see the impact site on Jupiter that was recently discovered by Australian amateur astronomer Anthony Wesley and are wondering how. You need a suitable telescope and to be looking at the correct time when the impact site is facing us.

Let’s start with the when can I see it question:

This weekend there will be a couple of good opportunities to see the Jupiter impact site from the West coast with amateur telescopes. Jupiter will both be up and the impact site will be facing towards us.

The impact site is at longitude 216 deg (CMII longitude system) and the iceinspace site has conveniently calculated transit times for the next few days. A transit time is when the impact site is directly facing Earth. AS Jupiter takes ~10 hours to complete one rotation there are several times per day:

2009 Jul 24 05:16 ( 216°) 15:12 ( 216°)
2009 Jul 25 01:08 ( 216°) 11:03 ( 216°) 20:59 ( 216°)
2009 Jul 26 06:54 ( 216°) 16:50 ( 216°)
2009 Jul 27 02:45 ( 216°) 12:41 ( 216°) 22:37 ( 216°)
2009 Jul 28 08:32 ( 216°) 18:28 ( 216°)
2009 Jul 29 04:23 ( 216°) 14:19 ( 216°)
2009 Jul 30 00:15 ( 216°) 10:10 ( 216°) 20:06 ( 216°)
2009 Jul 31 06:01 ( 216°) 15:57 ( 216°)

These are UTC so have to be converted to Pacific Time by subtracting 7 hours. The next few opportunities together with the altitude of Jupiter (how high it is in the sky) are:

Friday night: the best time is 4:03AM Sat morning (altitude 29 deg)

Saturday night: the best time is 11:54 PM (altitude 37 deg)

Saturday night is the best option as the altitude is higher. Jupiter has a ~10 hour day so viewing is good ~1.5 hours either side of these times, provided Jupiter is above the horizon.

So now we know when to look but what do we need to look with?

The impact site on Jupiter is ~1/100th the diameter of Jupiter or <1 arcsec across. This is about 1/6000th the size of the moon.

To see this you need a telescope with a resolution of 1 arcsec or better and suitable atmospheric viewing conditions – the strong color contrast between the dark mark and the planet will help however. A telescope of 5 1/2 in (138 mm) diameter or larger has enough resolving power. You will also need to have enough magnification.

The rule of thumb is that a magnification of 50X per inch of aperture is typically the maximum possible. This means that for a 6 in diameter telescope the maximum usable magnification for a well collimated telescope under good atmospheric seeing conditions is ~300X. The eyepiece needed to get this magnification is found by dividing the telescope focal length by the magnification. Thus for my telescopes I get these results:

Takahashi FC76 refractor
Diameter: 76 mm
Focal Length: 600 mm
Resolution comment: too small to resolve impact site
Max Magnification: ~150x
Eyepiece focal length for max.mag: 4 mm

Celestron C8 Schmidt Cassegrain
Diameter: 203 mm (8in)
Focal Length: 2032 mm
Resolution comment: Has sufficient resolution
Max Magnification: ~400X
Eyepiece focal length for max.mag: 5mm

Meade 12in Lightbridge
Diameter:304.8 mm (12 in)
Focal Length: 1524 mm
Resolution comment: Has sufficient resolution
Max Magnification: ~600x
Eyepiece focal length for max.mag: 2.5 mm

So I will be using my SCT to try to view (image actually) the impact site as the combination of aperture and focal length is best for this object.

Where to look for Jupiter?

If you need help finding Jupiter there are several resources:

Sky and Telescope interactive sky chart monthly star chart

and many others online.

Good luck and Clear Skies.

Moon, Venus and Jupiter

This was first published on December 2nd, 2008, republished January 12th 2019 after website move.

Moon, Venus and Jupiter setting

Tonight’s photo was taken a little later than last night’s photo so the sky background is darker and not so interesting. We can see how the moon and the Venus/Jupiter pair have swapped position. If you live in Europe then you had the opportunity to see the Moon eclipse Venus earlier today – unfortunately not visible from N. America. If you haven’t caught this grouping yet you will get another chance tomorrow night although the distance between the moon and Venus/Jupiter will be increasing. The next planetary occultation will be on Dec. 29th when the 3-day old moon will occult Jupiter however you will need to be in Central/Western Australia or Tasmania to see this. The next lunar occultation of a planet visible from N. America will be on Apr 22nd when the moon will again occult Venus.