Inferior Conjunction of Venus – June 2020

by Venus Observer, Milan B.

In two days (June 3rd, 2020), our twin sister planet will pass between us and the Sun. This brings fond memories of the similar passes in June 2004 and June 2012, which both resulted in transits across the solar disk, but this time around, Venus will just miss the solar disk by a quarter of a degree on its passage from northern to southern ecliptic latitudes.

Conjunction of Venus with the Sun on June 3rd, 2020, courtesy of Sky Safari

This 8 year cycle of Venus was known even to ancient Mayas. In 8 Earths years, Venus will make 13 orbits around the Sun and since both planets orbit the sun in the same direction, there will be 13 – 8 = 5 synodic periods of Venus looking from planet Earth. Any Fibonacci fans out there?

During 5 synodic periods Venus will go through 5 inferior conjunctions. Only one of these five is close to the Sun in the current epoque, two will be midway to the maximum distance which is just under 9 degrees and the remaining two will be very close to the maximum angular distance from the Sun.

5 synodic periods of Venus actually falls short of 8 years by 2 and a half days. With this, all inferior conjunctions will slowly move earlier in the year within each series. The 2020 conjunction, happening on June 3rd, is part of the June-May series, as was the 2004 transit, which occurred on June 8th and the 2012 transit, which occurred on June 5th.

With this years conjunction being a near miss, the question becomes: when will Venus next be so close to the solar disk? The visualisation below shows about 130 years of inferior conjunctions and each of the five seasons is labelled by the pair of months that it occurs in during the 21st century.

130 Years of Inferior Conjunction of Venus with the Sun, courtesy of Milan B. and Tableau

As the Jun-May series conjunctions (the green series above) are slowly moving away from the Sun and will not result in any transits for many centuries, we will need to turn to another series to bring us the next sequence of close passes and transits. The Jan-Dec series conjunctions, which are currently far from the solar disk are slowly inching (in astronomical terms) towards the Sun and also regressing from mid January (in early 2000’s) into early December (in the early 2100’s) which will result in another pair of transits, this time the December transits of 2117 and 2125.

Venus one week after the 2015 Inferior Conjunction, Aug 22nd 2015, courtesy of Milan B. and SkyWatcher.

From the chart above it becomes apparent that after the June 2020 conjunction, Venus will not venture so close to the Sun (from Earths perspective) for another 97 years, until the 2117 transit. Hopefully, some of the younger generations will get a chance to see this remarkable astronomical event.

Imaging Two Pinwheel Galaxies

I found it interesting to compare images of two Pinwheel galaxies despite the difference in targets and imaging setups.

The Pinwheel Galaxy, M101 in Messier’s catalogue, is a beautiful face-on spiral galaxy that is popular with astrophotographers. Tonight at 11:00 pm from Vancouver, it is at an altitude of 84°- almost straight up – in the constellation Ursa Major. This is a great location for visual observing or imaging to minimize atmospheric disturbance.  I collected image data of M101 in 2014 with a small 100 mm refractor.

Another pinwheel from Messier’s catalogue is M83, also known as the Southern Pinwheel. It is visible at the same time but its altitude is just 10° above the southern horizon in the constellation Hydra when viewed from Vancouver. That location makes M83 a difficult target so I decided to use a remote telescope in Chile at latitude 30°S.  From Chile, M83 reaches 89° when transiting the meridian at 02:16 am UTC.

Click on the image to open a larger view.

Two very different setups were used to collect the imaging data. The M101 data was collected using my own equipment from Coquitlam, BC:

  • Skywatcher 100ED pro refractor
  • Nikon D5100 DSLR
  • Total Exposure:  30 min with 20 subframes at 90 sec and ISO 1600
  • Heavy light pollution (sqm: 18.5, Bortle class 7)

The M83 data was from the Telescope.live remote CH-1 telescope in Chile:

  • Planewave CDK24 (60 cm, F6.5)
  • FLI ProLine PL900 (3056 x 3056)
  • Total Exposure: 90 min with  9 Luminance and 3 each of Red, Green, Blue subframes at 300 sec and 1 x binning.
  • Pristine Dark skies at an elevation of 1500 m (sqm: 21.8, Bortle class 1) – same skies as the Gemini South telescope.

So it is not at all surprising that the M83 image is better with 6X more aperture and 3X longer exposure.

The two galaxies are both face-on spirals, appear somewhat similar, and are close to the same visual magnitude but some of their physical properties are quite different as shown in the table below.

M101M83
ConstellationUrsa MajorHydra
Visual magnitude7.867.54
Angular Size28′.8 × 26′.912′.9 × 11′.5
Distance1.8 Mly14.7 Mly
Diameter170,000 ly55,000 ly
Radial velocity241 ± 2 km/s508 km/s
Number of Supernovae

6

M83 has spawned a large number of supernova explosions — six in total that we have observed (SN 1923A, SN 1945B, SN 1950B, SN 1957D, SN 1968L, and SN 1983N).  Only 4 supernovae have been observed in M101 but SN 2011fe, a Type Ia supernova, reached magnitude 9.9 in 2011 and was visible in binoculars.

M83 is thought to have a double nucleus at its core. The paper  “Double nucleus in M83” provides evidence of a second hidden nucleus that is more massive than the visible nucleus.

Search for Micrometeorites when Cleaning Your Gutters

Micrometeorite Images
Image Credit: A display of nine of the most spectacular micrometeorites from Jon Larsen’s collection

It is a good time to clean out your rain gutters before the fall rains start in earnest and you can slip in some astronomy by checking the debris for meteorites.   

We are familiar with meteors or shooting stars that leave streaks of light as they burn up in Earth’s atmosphere but 5 to 300 tons of space dust and debris hit the Earth’s surface every day. Impacts of large meteorites are rare but micrometeorites, those that are smaller than a grain of rice (50 µm to 2 mm in diameter) are quite common.  A rough estimate is that one micrometeorite lands in any square meter per year so your roof might bear a number of micrometeorites.  

The challenge is separating the micrometeorites from the other terrestrial debris and using a good magnet to pull out nickel and iron laden rocks is the key. An easy way to collect them is to place some strong magnets in a plastic bag and hang it near the outlet of the rain gutters. The magnet collects the nickel- and iron-laden micrometeorites, plus other magnetic debris,  as the rain washes them off the roof. The next step is to use a microscope to separate the good stuff: micrometeorites are spherical and have a glass coating formed as they heat up when passing through the Earth’s atmosphere.  

Micrometeorites and Debris Magnified
Image credit: Wayne Schmidt – The actual width of the area covered in this image is 1/8th inch

There is a good chance that some of the “micrometeorites” you’ll identify are actually formed in terrestrial processes that put particles with the appearance of micrometeorites into the air, such as volcanic eruptions or burning coal. Jon Larsen’s Project Stardust Facebook page has detailed tips on correctly identifying the micrometeorites. Hundreds of fascinating images of micrometeorites are included in his book “In Search of Stardust“.

Building An Inexpensive Artificial Star

Good collimation is important for getting the best performance from a telescope. I recently installed Bob’s Knobs on my Celestron SCT to help with collimation – mostly to reduce the risk of damaging the corrector lens when fumbling at night with a screwdriver. Unfortunately, installing the knobs put the telescope way out of collimation – it wasn’t just a minor mis-alignment, in-focus stars were comet shaped and the out-of-focus stars appeared as crescents rather than the desired donut pattern. I spent a couple of hours, over two nights, trying to improve the collimation to no avail but some Google searches and building an incredibly simple artificial star helped.

Flashlight with aluminum foil
An Inexpensive Artificial Star from a bike light and aluminum foil.

An artificial star is a small point of light that is used for collimation or optics testing. With an artificial star, collimation can be done during the day and doesn’t require clear skies or good seeing conditions. Artificial stars are available commercially from $25 USD but a precision artificial star is not required for rough collimation so I “built” one for free using a bike light and aluminium foil.

I started by poking four small holes in a piece of aluminium foil with a sewing needle while varying the pressure to produce holes of different sizes. The foil was then wrapped around a bright MEC bike light and secured with a rubber band.

startest_collimation_in_tweaked
The donut pattern on a out-of-focus real star after tweaking collimation.

I set up the telescope on its mount in my yard and aimed it at the artificial star which was placed on on barrel about 20 meters away. The second largest hole produced the best image when viewed through the telescope so I put a bit of tape over the other holes to block them out then followed these instructions to restore rough collimation in about ½ hour. A few minutes of tweaking at night produced a much improved view and the expected donut pattern on an out-of-focus star.

Perseid Meteor Shower Peak – 2016

This year’s Perseid meteor shower is expected to peak late on Thursday Aug 11 or in the early morning on Friday Aug 12.  Under good dark-sky conditions, you can expect to see 40 to 80 meteors per hours.  Be patient, the Perseids do not create a blizzard of streaksthrough the sky:  60 meteors an hour means an average of just one per minute, and that includes many faint ones.   From locations in the Lower Mainland with moderate light pollution, you are more likely to see one meteor every two or three minutes.

There is often a good show of meteors several days after the peak so the Perseid Meteor Shower Watch event on Saturday at Aldergrove Region Park is great chance to the shower.

PersiedsShower_Chart

Ten Perseid Meteor Facts:

  1. The Perseid Meteor shower has been observed for over 1000 years.  In 33 AD,  a Chinese skywatcher reported that “more than 100 meteors flew thither in the morning” but when the shower first occurred is unknown.
  2. The Perseid meteors are caused by the Earth passing through the debris trail left by Comet Swift-Tuttle which orbits the sun once every 133 years.
  3. The meteors are the pieces of debris,  usually no bigger than a grain of sand, that enter the Earth’s atmosphere.
  4. More meteors are expected this year because the Earth will be moving through a thicker clump of debris from Swift-Tuttle, created partly from the influence of Jupiter’s gravity.
  5. The Perseid meteors strike the atmosphere at a high velocity, about 60 kilometers per second, which tends to produce bright meteors and an unusual number of super-bright meteors, called fireballs.
  6. The Perseid meteors appear to come from the same place: the constellation Perseus, also called the “radiant.” Perseus is found in the northeastern part of the sky.
  7. Light from the moon will interfere somewhat this year but the moon sets at 12:53 AM on August 12.
  8. Observers have photographed Perseids striking the moon.
  9. People have claimed to hear sounds associated with meteor: hissing, sizzling, or pops.  Scientists have recently proposed that that very frequency radio waves created by meteors could vibrate metal objects on the ground.
  10. An astronaut on the International Space Station, Ron Garan, watched the Perseid meteors from space by looking down at the Earth.

Perseid meteor viewed from the ISS

Space Suite II Launched on BC's Knowledge Network

BC’s Knowledge Network recently launched a program called “Space Suite II” and it’s a follow-up to their popular series of short films that comprise the original Space Suite.  The video below is one of ten short films that make up Space Suite II. The piece is titled “Clearer From Afar” and explores the context of the planet Earth from those who have been lucky enough to see it in its entirety.

YouTube: https://youtu.be/4F70wwwtY_s
Vimeo: https://vimeo.com/174578034
Facebook: http://bit.ly/29Py1OC

Full Space Suite II: www.knowledge.ca/program/space-suite-ii

Telescope Sale at Monthly Meeting on Thurs July 14th, 2016

At the next monthly meeting, we will have a silent auction of several old telescopes and accessories that were part of the telescope loan program. We are doing this to clear space in the storage area and to raise funds for some new telescopes and mounts.

Celestron_NexStar_8
Celstron NextStar 8 with a Goto Mount

 

Below is a list of the items we plan to sell.  The show-case item is a Celestron Nexstar 8” with GOTO mount.
In addition to this list there will be several eyepieces and odds-and-ends for sale.

There will be minimum bids. We may be able to issue tax receipts if the final bid amount exceeds the item’s value by a certain amount (if 80% of the bid is above the value of the amount, a receipt can be issued for the difference).
 

Item
Description
 Value
1
Skywatcher 90mm refractor with GE mount
$200
2
Orion “Space Explorer” 8” (maybe 6?) Dobsonian
$400
3
Meade ETX-125 Maksutov Cassegrain with mount
$400
4
Small Celestron Tripod
$10
5
Celestron Clock Drive
$20
6
HOC 90mm Refractor (no mount)
$250
7
EQ Mount
$50
8
LDx55 Mount and Tripod
$350
9
LDx55 Mount (no tripod)
$200
10
Celestron Nexstar 8” with GOTO mount
$1000
11
Hand-made 6” Dobsonian (needs work)
$200
12
80mm Celestron Refractor
$150
13
80mm Karl Weser Refractor
$150