The Great Conjunction of 2020

Are you ready for the Great Conjunction on December 21st? This rare astronomical event refers to when the planets Jupiter and Saturn appear close to each other in the sky. This event occurs in an approximately 20-year cycle. The approach will be very close, at a separation of only 6 arcseconds between the planets! The last time these planets appeared this close was in 1623, and the next time will be in 2080. Make sure to take the once-in-a-lifetime chance to observe Saturn and Jupiter simultaneously! The planets will be low on the south-western horizon as the sun sets, so get your telescopes and binoculars from Orion Telescopes and Binoculars ready for this rare observing opportunity!

At the 2000 great conjunction, 20 years ago, Jupiter and Saturn were near the sun in our sky and difficult to observe. We are due for a more observable great conjunction, and we’ll get one. In November, Jupiter and Saturn were noticeable for their nearness to each other, and they were in the sky when darkness fell.

In December 2020, Jupiter and Saturn will still be easily visible. They’ll be, if anything, even more beautiful in the western twilight shortly after sunset.

On the 21st December 2020, Jupiter and Saturn will be separated by only 6 arcminutes, the closest conjunction since 1623. Source: Sky Safari 5 Pro.

You’ll recognize Jupiter and Saturn easily from now through the end of the year. Jupiter is brighter than any star. Saturn is not as bright as Jupiter, but it’s as bright as the brightest stars and shines with a distinctive golden color. Also, Jupiter is near Saturn! Saturn is just to the east of Jupiter on the sky’s dome. Unlike the twinkling stars, Jupiter and Saturn both shine steadily.

Over the time between November 21 and the day of the conjunction itself, December 21, Jupiter will travel about 6 degrees and Saturn 3 degrees on the sky’s dome. That movement will mean that Jupiter bridges the 3-degree gap between itself and Saturn.

Whenever Jupiter and Saturn are in conjunction, that is, when they have the same right ascension or celestial longitude, it is referred to as a "Great Conjunction," primarily because, unlike conjunctions with the other bright planets, these two don't get together very often. The average frequency of occurrence is merely the product of their sidereal periods divided by the absolute value of their difference.

A sidereal period is defined as the time required for a celestial body within the solar system to complete one revolution with respect to the fixed stars. Saturn's period of 29.65 years multiplied by Jupiter's period of 11.86 years amounts to 351.65. Dividing this value by the difference in their sidereal periods gives us 19.76 years. So, about every 20 years, Jupiter and Saturn will have a rendezvous.

Insight Observatory's remote telescopes ATEO-1 (left) and ATEO-2A (right) will attempt to gather image data of the "Great Conjunction of 2020" from SkyPi Remote Observatory on the evening of December 21, 2020.

Insight Observatory will be attempting to acquire image data of this rare event on the evening of December 21st on its remote Astronomical Telescopes for Educational Outreach (ATEO) from SkyPi Remote Observatory in New Mexico. The conjunction will be extremely low in the southwest part of the sky from our location at SkyPi; however, we are going to give it a try. If you are interested in receiving image data, please contact us.

Sources: Earthsky.org and Space.com

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What's In The Sky - November 2020

Clear November night skies offer incredible celestial sights recommended by Orion Telescopes and Binoculars for stargazers to be thankful for, so bundle up and get outside for stargazing fun!

Double Cluster in Perseus
Use a pair of big binoculars or a shorter focal length telescope with a wide-field eyepiece in November to seek out the sparkling Double Cluster in Perseus - two side-by-side open star clusters NGC 884 and NGC 869. 

NGC 884 and NGC 869 - The Double Cluster in Perseus imaged by Claudio Tenreiro on Insight Observatory's 16" f/3.7 astrograph reflector (ATEO-1).

Mars & The Moon

On November 25th, the Moon passes close by Mars, making them a great observing target! The pair will be separated by approximately 5.5 degrees, which is unfortunately too far apart to be viewed simultaneously at high magnification, but both could be observed together with wide-angle astronomy binoculars.

New Moon
November 14th will be the best time of the month to observe the fainter deep-sky objects such as galaxies and star clusters because there is no moonlight to interfere.

Leonids Meteor Shower
Bundle up and get outside after midnight on November 17th to see the peak of the Leonids meteor shower as "shooting stars" appear to radiate outwards from the constellation Leo. Meteor showers are usually best viewed without optical equipment, but for a closer look, try out some Ultra Wide Angle Binoculars. The shower peak is very close to the New Moon, which should present little light pollution. The estimated peak rate is approximately 14 meteors per hour.

 

M45 - The Pleiades located in the constellation Taurus imaged by Plymouth South Middle School students Taylor A. and Kyleigh O. using ATEO-1 via Insight Observatory's online Educational Image Request (EIR) application.

The Pleiades
November is sometimes called "the month of the Pleiades," since the star cluster is visible all night long for observers in the Northern hemisphere. From a dark sky site, M45 is easy to see with the unaided eye and resembles a small "teaspoon" pattern in the sky. Use astronomy binoculars for immersive views of this open star cluster, or use a telescope with a lower-power eyepiece for a closer look at the Seven Sisters.

All objects described above can easily be seen with the suggested equipment from a dark sky site, a viewing location some distance away from city lights where light pollution and bright moonlight do not overpower the stars.

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Wolf 359 Star Parallax

Using Insight Observatory's 16" f/3.75 Dream Aerospace Systems astrograph reflector (ATEO-1) remote telescope, a Romanian team of amateur astronomers participated in the international project #NHParallax. This project is aimed to highlight the parallax effect by comparing image frames from the New Horizons space probe combined with frames obtained by ground-based remote telescope ATEO-1 located in New Mexico, USA.

Introduction:
Historically, the first determination of the distance to the stars was made by astronomer Friedrich Bessel in 1838 for the star 61 Cygni using the parallax method. This method remained the standard procedure for calibrating other methods for determining distances in the Universe. The parallax of a star is the angle through which the radius of the Earth's orbits is seen from the star when it is perpendicular to the Earth-Star direction. The simplified model of the parallax effect is illustrated in Figure 1. It involves a change in the apparent position of a star relative to the stars from the background when observed from two different locations. This is quantified by the angle p - called the parallax.

Figure 1 - Parallax Effect

For the calculation of the distance, we refer to Figure 1.

The following equations can be written:

tg (p ”) = Earth-Sun Distance / Sun-Star Distance
tg (p ”) = 1UA / D, from which it follows that:
D = 1 / tg (p ”)
Since the angle p ”is very small (less than one second of arc) we can approximate tg (p”) = p ”and the formula becomes:
D = 1 / p ”,
where D is expressed in parsecs (pc)
p” is expressed in arcseconds and 1 AU represents an astronomical unit, ie the average Earth-Sun distance.

Traditionally the distances to Proxima Centauri and Wolf 359 were calculated using this method and resulted in the following data confirmed by the specialized space missions Hiparchos and Gaia:

p”Wolf 359 = 0.41516” ± 0.000162 ”

The distance to the star Wolf 359 = 2,409 ± 0.009 pc, ie 7.86 light-years (+/-0.03 ly) 

Remarks:
On April 22, 2020, we made observations with the ATEO-1 remote telescope in tandem with the New Horizons space probe at nearby star Wolf 359. The advantage of these tandem observations is that the New Horizons probe is 46 times the Earth-Sun distance, which causes the perspective of the probe on the star Wolf 359 to change visibly from the perspective observed on earth. With such a large distance between the two observation points (Earth - New Horizons), the parallax effect is easy to highlight by comparing photos taken from Earth with those received from the New Horizons probe. Here is the animation which shows a stereo view of this phenomenon.

Wolf 359 Star animation with image data acquired from the New Horizons space probe
 and Insight Observatory's ATEO-1 remote telescope located in New Mexico.

The raw images obtained by the New Horizons space probe were downloaded from the website below dedicated to this project:

http://pluto.jhuapl.edu/Learn/Parallax/Parallax-Images.php

The camera used by the space mission was the Long-Range Reconnaissance Imager (LORRI). The raw images required some processing to eliminate image artifacts. This was done in the following steps:

- Creation of synthetic flat and removal of cosmic rays and hot pixels.
- Slight convolution of stars.

In order to measure the parallax angle, we must calibrate the two images in coordinates relative to the celestial sphere. This calculation was performed using the Astrometry.net program.

We determined the astrometric solution of the plate in the ICRS J2000 (International Celestial Reference System). Because the LORRI camera aboard the New Horizons spacecraft was designed to take images of trans-Neptunian objects, its resolution is only 4,09 arcsec/pixel as opposed to the much better resolution ATEO-1 telescope provides, ie 1,237 arcsec /pixel.

Results:
Since the geometry of the observations is more general than in the simplified model, respectively the Wolf 359 star is not centered in relation to the observation base. We first measured the angular distance between the star and the New Horizons probe at the date of the observation. The following were obtained:

θNH-Wolf359 = 125.20785° - The angular separation between New Horizons and Wolf 359.

According to the Jet Propulsion Laboratory website at the time of the observations, the distance between the Earth and the New Horizons spacecraft was 46.8534 AU, ie 7.028 billion kilometers. We measured the position of the Wolf star on the New Horizons frames and on the images obtained with the ATEO-1 telescope. We used all the images (3 provided by the New Horizons probe and 6 purchased with the telescopes we used) and averaged these measurements. To evaluate the measurement error we calculated their standard deviation. The results obtained are presented in Table 1.

Table 1: Wolf 359 star coordinates in both images obtained by the 
New Horizons probe and ATEO-1 telescope - ICRS2000.

An important aspect of these measurements, given that the pixel size is large compared to the star's profile, is the algorithm for identifying the centroid of each star in the images. For this, we used two methods: the position of the brightest pixel and the algorithm proposed by the AstroImageJ program.

To calculate the parallax, we used the formula for calculating the angular separation (Jean Meus - Astronomical Algorithms). In this formula, α and δ are the right ascension and the declination and the indices 1 and 2 correspond to the measurements with our telescope, respectively with the New Horizons probe.

cos d = sinδ1 sinδ2 + cosδ1 cosδ2 cos (α1 - α2)

Based on this formula we obtained the following parallaxes. I marked it with d to differentiate it from the meaning described in the introduction.

d”Wolf359 = 16,479” ± 3,390 ”

Figure 3: The geometry of the Earth, New Horizons space probe, and Wolf 359 star on April 22, 2020.

Taking into account the geometry of the observation (Figure 3) the distance can be calculated using the formula:

distEarth-Wolf359 ≈ distEarth-New Horizon / tg (d”) * sin (θ),

where distEarth-Wolf359 is the distance from Earth to the Wolf star, distEarth-New Horizon= 46.8534 AU is the distance from Earth to the New Horizons probe, and sin (θ) is the factor that takes into account the geometry of the observation.

We obtained the following distance for Wolf star:

distEarth-Wolf359 = 7,576 ± 1,559 light-years.

Conclusions:
This result corresponds to the recent determinations reported by the Gaia space mission and presented in the introduction. Our measurement has a lower degree of accuracy due to the low resolution of the LORRI (Long Range Reconnaissance Imager) camera with which the images from the New Horizons probe were recorded. This camera has a resolution of 4.09 ”/ pixel which means that a one-pixel position measurement error is a 10-20% parallax error (depending on the star). The approximations made in this calculation are insignificant in relation to the error in determining the position.

NASA's #NHParallax project to measure parallax by performing tandem observations on Wolf 359 and Proxima Centauri stars with the New Horizons spacecraft was purely educational, with NASA encouraging amateur astronomers around the world to make observations with their instruments at the same time as the space probe.

More details about this project can be found on the official website of the New Horizons mission:

http://pluto.jhuapl.edu/Learn/Get-Involved.php#NHparallax

The FITS files from the New Horizon space probe can be downloaded here:

http://pluto.jhuapl.edu/Learn/Parallax/Parallax-Images.php

The movement of the two stars is very difficult to visualize in the frames recorded on Earth, six months away because the parallax angle is extremely small compared to the star profile caused of the atmospheric disturbance recorded by the best observatories. The present project has managed to clearly illustrate this effect.

Authors Affiliation: 
Daniel Bertesteanu - Bucharest Astroclub
Marcel Popescu - Astronomical Institute of the Romanian Academy
Marian Naiman - Bucharest Astroclub

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