In the Sky This Week – October 27, 2020

I’m a volunteer ambassador for NASA’s OSIRIS-REx asteroid sample return mission – I can not tell you how excited I am about the recent successful, maybe overly successful, sample acquisition from the surface of asteroid Bennu! The sample head is full of rocks an dust, and apparently a large rock has prevented a mylar flap from sealing the sample head, and some smaller rocks are escaping! The sample head should be safely stowed away today  – that can’t happen soon enough for me!

The pandemic has prevented me from doing in-person lectures about the mission, but I’ve been covering the mission in these weekly posts, and I was able to book Dolores Hill from the OSIRIS-REx mission to speak at the Astronomy at the Beach event – so I don’t feel too awful about my lack of lecturing…

The red giant star Arcturus competes with Venus for the title of “morning star” in the eastern predawn sky … Venus wins!

Venus and the red giant star Arcturus appear in the eastern predawn sky all week. Credit: Stellarium / Bob Trembley.

The Moon dances with Mars from Oct. 27th – 31st in the eastern sky after sunset.

The Moon dances with Mars from Oct. 27th – 31st in the Credit: Stellarium / Bob Trembley.

Saturn and Jupiter appear in the southern sky at sunset – the pair of planets appear low on the southwestern horizon at 10:30 PM.

Saturn and Jupiter appear in the southwestern sky at dusk. Credit: Stellarium / Bob Trembley.

The Moon is a waxing gibbous – visible to the southeast in early evening, up for most of the night.

The full Moon occurs on Nov. 1st – it rises at sunset, is visible high in the sky around midnight, and is visible all night.

After Nov. 1st, the Moon will be a waning gibbous – rising after sunset, visible high in the sky after midnight, and visible to the southwest after sunrise.

The Moon from 2020-10-27 – 2020-11-02. Visualizations by Ernie Wright / NASA’s Scientific Visualization Studio.

If you click on the Moon image above, or click this link, you will go to NASA’s Moon Phase and Libration, 2020 page – it will show you what the Moon looks like right now. If you click the image on that page, you will download a high-rez TIF image annotated with the names of prominent features – helpful for logging your observations!

Annotated close-up of a section of the Moon on Oct. 27th (left) and Nov. 2nd (right) – showing the play of shadows. Visualizations by Ernie Wright / NASA’s Scientific Visualization Studio.

Moon News

Sunspot AR2778 is the largest of new solar cycle #25; SpaceWeather.com says “The primary dark core of AR2778 is about the size of Earth. Altogether, the sunspot group sprawls 90,000 km across the face of the sun, dimensions which make it an easy target for backyard solar telescopes. Amateur astronomers with safely-filtered optics are encouraged to monitor developments.” When I was editing the image below, I noticed the tiny sunspot in the upper right – it’s not labeled on SpaceWeather.com, and I’m not sure if this is a new sunspot or an older one.

Sunspots on 2020-10-27. Credit: NASA/SDO and the AIA, EVE, and HMI science teams. Edited by Bob Trembley.

The southern coronal hole has diminished from last week – the northern coronal hole has made up for it in size and tendrils; there are several regions of intense coronal loop activity.

The Sun seen in 193 angstroms (extreme ultraviolet) October 26, 2020:

Prominences everywhere! Keep you eye on the middle of the Sun’s northern hemisphere during the last second of the video below!

The Sun seen in 304 angstroms (extreme ultraviolet) October 26, 2020:

Solar Activity on Facebook – Run by Volunteer NASA/JPL Solar System Ambassador Pamela Shivak

The SOLARACTIVITY PICTURE OF THE DAY for October 27th, 2020 is this awesome prominence lifting off by Jim Ferreira from California using a Daystar filter.

Solar Corona

Solar wind speed is 508.0 km/sec (↑↑), with a density of 7.9 protons/cm³ (↑) at 1320 UT.

Near real-time animation of the corona and solar wind from the Solar & Heliospheric Observatory (SOHO):

Animated LASCO C2 Coronograph showing the solar corona above the Sun’s limb (the white circle). Credit: NASA/JPL-Caltech-SOHO

Sun News

Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. Red highlighted entries are asteroids that either pass very close, or very large with high relative velocities to the Earth. Table from SpaceWeather.com

On October 26, 2020, the NASA All Sky Fireball Network reported 8 fireballs. 
(6 sporadics, 2 Orionids)

In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). Credit: SpaceWeather.com

Fireball News

Position of the planets in the inner solar system:

Position of the planets and a couple spacecraft in the inner solar system, 2020-10-27. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets in the middle solar system:

Position of the planets in the middle solar system, 2020-10-27. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets, some dwarf planets and some transneptunian objects in the outer solar system.

Position of the planets and some transneptunian objects in the outer solar system, 2020-10-27 – the orbit of TNO Haumea is highlighted. Credit: NASA Eyes on the Solar System / Bob Trembley.

Solar System News

NASA’s OSIRIS-REx Asteroid Sample Return Mission:

International Space Station: #SpaceStation20th

HiRISE – on the Mars Reconnaissance Orbiter:

Lunar Reconnaissance Orbiter:

Climate: View the Earth as your Mother, not as a trash can.

See a list of current NASA missions here: https://www.jpl.nasa.gov/missions/?type=current

ex·o·plan·et /ˈeksōˌplanət/, noun: a planet orbiting a star other than the Sun.

Data from the NASA Exoplanet Archive
* Confirmed Planets Discovered by TESS refers to the number planets that have been published in the refereed astronomical literature.
* TESS Project Candidates refers to the total number of transit-like events that appear to be astrophysical in origin, including false positives as identified by the TESS Project.
* TESS Project Candidates Yet To Be Confirmed refers to the number of TESS Project Candidates that have not yet been dispositioned as a Confirmed Planet or False Positive.

Hubble: Beautiful Universe

Tour of the Local Stellar Neighborhood

Continuing with my visual tour of nearby stars and their systems, we travel to the Ross 780 (Gliese 876) system, about 15 light years distant.

Gliese 1002 is about 15 light years from Sol; the plane (green) is aligned with the orientation of the plane of the Milky Way galaxy. Credit: SpaceEngine / Bob Trembley.

Gliese 876

Gliese 876 is a red dwarf approximately 15 light-years away from Earth in the constellation of Aquarius. It is one of the closest known stars to the Sun confirmed to possess a planetary system with more than two planets, after Gliese 1061, YZ Ceti, Tau Ceti, and Luyten’s Star; as of 2018, four extrasolar planets have been found to orbit the star. The planetary system is also notable for the orbital properties of its planets. It is the only known system of orbital companions to exhibit a near-triple conjunction in the rare phenomenon of Laplace resonance (a type of resonance first noted in Jupiter‘s inner three Galilean moons). It is also the first extrasolar system around a normal star with measured coplanarity. While planets b and c are located in the system’s habitable zone, they are giant planets believed to be analogous to Jupiter.

On June 23, 1998, an extrasolar planet was announced in orbit around Gliese 876 by two independent teams led by Geoffrey Marcy and Xavier Delfosse. The planet was designated Gliese 876 b and was detected by Doppler spectroscopy. Based on luminosity measurement, the circumstellar habitable zone (CHZ) is believed to be located between 0.116 and 0.227 AU. On January 9, 2001, a second planet designated Gliese 876 c was detected, inside the orbit of the previously-discovered planet. The relationship between the orbital periods initially disguised the planet’s radial velocity signature as an increased orbital eccentricity of the outer planet. Eugenio Rivera and Jack Lissauer found that the two planets undergo strong gravitational interactions as they orbit the star, causing the orbital elements to change rapidly. On June 13, 2005, further observations by a team led by Rivera revealed a third planet, designated Gliese 876 d inside the orbits of the two Jupiter-size planets. In January 2009, the mutual inclination between planets b and c was determined using a combination of radial velocity and astrometric measurements. The planets were found to be almost coplanar, with an angle of only 5.0^+3.9
_−2.3° between their orbital planes.

On June 23, 2010, astronomers announced a fourth planet, designated Gliese 876 e. This discovery better constrained the mass and orbital properties of the other three planets, including the high eccentricity of the innermost planet. This also filled out the system inside e’s orbit; additional planets there would be unstable at this system’s age. In 2014, reanalysis of the existing radial velocities showed the possible presence of two additional planets. These planets would have almost the same mass as Gliese 876d. In 2018 a study using hundreds of new radial velocity measurements found no evidence for these planets. If this system has a comet disc, it is undetectable “brighter than the fractional dust luminosity 10⁻⁵” of a recent Herschel study. None of these planets transit the star from the perspective of Earth, making it difficult to study their properties.

GJ 876 is a candidate parent system for the ʻOumuamua object. The trajectory of this interstellar object took it near the star about 820,000 years ago with a velocity of 5 km/s, after which it has been perturbed by six other stars.  – Wikipedia

Gliese 876 System Diagram

Ross 780 (Gliese 876) System Diagram. Credit: SpaceEngine / Bob Trembley.

Gliese 876 Orbital Diagrams

Ross 780 (Gliese 876) Orbital Diagram – Top View. Credit: SpaceEngine / Bob Trembley.

Ross 780 (Gliese 876) Orbital Diagram – Side View. Credit: SpaceEngine / Bob Trembley.

Artist Rendering of a Hot Subneptune Exoplanet Orbiting Gliese 876

Artistic rendering of a hot subneptune exoplanet orbiting red dwarf star Gliese 876. Credit: SpaceEngine / Bob Trembley.

Cover Image:

Captured on Oct. 22, this series of three images shows that the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) sampling head on NASA’s OSIRIS-REx spacecraft is full of rocks and dust collected from asteroid Bennu, as well as the fact that some of these particles are escaping the sampler head. Analysis by the OSIRIS-REx team suggests that bits of material are passing through small gaps where the head’s mylar flap is slightly wedged open. The mylar flap (the black bulge visible in the 9 o’clock position inside the ring) is designed to keep the collected material locked inside, and these unsealed areas appear to be caused by larger rocks that didn’t fully pass through the flap. Based on available imagery, the team suspects there is plentiful sample inside the head, and is on a path to stow the sample as quickly as possible. The images were taken by the spacecraft’s SamCam camera as part of the sample verification procedure following the spacecraft’s Oct. 20 sample collection attempt. The TAGSAM system was developed by Lockheed Martin Space to acquire a sample of asteroid material in a low-gravity environment. Credit: NASA/Goddard/University of Arizona

What I was listening to when I was editing this:

Stay safe, be well, and look up!

Apps used for this post:

NASA Eyes on the Solar System: an immersive 3D solar system and space mission simulator – free for the PC /MAC. I maintain the unofficial NASA Eyes Facebook page.
Universe Sandbox: a space simulator that merges real-time gravity, climate, collision, and material interactions to reveal the beauty of our universe and the fragility of our planet. Includes VR support.
SpaceEngine: a free 3D Universe Simulator for Windows. Steam version with VR support available.
Stellarium: a free open source planetarium app for PC/MAC/Linux. It’s a great tool for planning observing sessions. A web-based version of Stellarium is also available.

Section header image credits:
The Sky – Stellarium / Bob Trembley
Observing Target – Turn Left at Orion / M. Skirvin
The Moon – NASA/JPL-Caltech
The Sun – NASA/JPL-Caltech
Asteroids – NASA/JPL-Caltech
Fireballs – Credited to YouTube
Comets – Comet P/Halley, March 8, 1986, W. Liller
The Solar System – NASA Eyes on the Solar System / Bob Trembley
Spacecraft News – NASA Eyes on the Solar System / Bob Trembley
Exoplanets – Space Engine / Bob Trembley
Light Pollution – NASA’s Black Marble
The Universe – Universe Today