In the Sky This Week – June 30, 2020

June 30th is International Asteroid Day, a UN recognized day of awareness and education about asteroids – their role in the formation of our solar system, how we can use their resources, how asteroids can pave the way for future exploration, and how we can protect the Earth from asteroid impacts; I have been a supporter of #AsteroidDay since day 1. June 30th is the anniversary of the 1908 Tunguska impact event – which leveled 830 square miles of forest in a remote region of Russia.

I’m a complete asteroid fanatic, and I’ve been lecturing about asteroids since before #AsteroidDay came into existence; during #AsteroidDay events at the Cranbrook Institute of Science, I’ve given live-demos of an asteroid rendezvous, capture and redirect missions in Kerbal Space Program – one of the asteroid captures was a bit to fast, and I plowed into the asteroid, destroying my probe… in front of a live audience… woohoo!

A small asteroid captured and redirected by a small probe. Credit: Kerbal Space Program / Bob Trembley

The Moon appears in the southern sky after sunset early this week – passing through the constellation Sagittarius.

The conjunction of Saturn and Jupiter continues to appear in the southwestern predawn sky all week.

Saturn and Jupiter in conjunction, appearing in the southwestern sky at 4:30 AM this week. Credit: Stellarium / Bob Trembley.

The Moon joins the pair of planets for a couple days in the first week of July – passing very close to them on July 5th.

Close-up of the conjunction of the Moon, Jupiter and Saturn in the southeastern sky 10:30 PM on July 5th. Credit: Stellarium / Bob Trembley.

Mars appears in the eastern sky during the early morning hours this week.

Mars appears in the eastern early-morning sky this week. Credit: Stellarium / Bob Trembley.

Venus appears in the east-northeastern predawn sky near the Pleiades star cluster all week.

Venus appears in the east-northeastern predawn sky this week. 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 July 5th – rising at sunset, visible high in the sky around midnight, and visible all night.

After July 5th, 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 2020-06-30 – 2020-07-06. Visualizations by Ernie Wright / NASA’s Scientific Visualization Studio.

Moon News

The Sun has been spotless for 2 days, so apparently there was a spot that lasted for only a couple days after my last post. Coronal holes remain open at both poles, and a couple small coronal holes pepper the face of the Sun.

The Sun seen in 193 angstroms (extreme ultraviolet)  June 29, 2020:

Prominences galore over the last few days! Some beautiful long-lived prominences, and a big loop too!

The Sun seen in 304 angstroms (extreme ultraviolet) June 29, 2020:

Facebook: SolarActivity – Run by Solar System Ambassador Pamela Skivak

https://www.facebook.com/photo.php?fbid=10220355679635846&set=gm.3319702601374394&type=3&theater&ifg=1

Solar Corona

Solar wind speed is 328.6 km/sec (↑), with a density of 9.0 protons/cm³ (↑) at 1135 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

Upcoming Earth-asteroid encounters:

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

Asteroid News – June 30th is International Asteroid Day

On June 28, 2020, the NASA All Sky Fireball Network reported 8 fireballs. 
(8 sporadics)

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

https://twitter.com/AstroBalrog/status/1277948219692064768

Position of the planets and a couple spacecraft in the inner solar system:

Position of the planets and a couple spacecraft in the inner solar system, 2020-06-29. 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, 2020-06-29. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets some transneptunian objects in the outer solar system:

Position of the planets in the outer solar system, 2020-06-29. Credit: NASA Eyes on the Solar System / Bob Trembley.

Highlight: Mars

I LOVE this photo of Mars!

The largest canyon in the Solar System cuts a wide swath across the face of Mars. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep. By comparison, the Earth’s Grand Canyon in Arizona, USA is 800 kilometers long, 30 kilometers across, and 1.8 kilometers deep. The origin of the Valles Marineris remains unknown, although a leading hypothesis holds that it started as a crack billions of years ago as the planet cooled. Recently, several geologic processes have been identified in the canyon. The above mosaic was created from over 100 images of Mars taken by Viking Orbiters in the 1970s. Image Credit: NASA

Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, being only larger than Mercury. In English, Mars carries the name of the Roman god of war and is often referred to as the “Red Planet“. The latter refers to the effect of the iron oxide prevalent on Mars’ surface, which gives it a reddish appearance distinctive among the astronomical bodies visible to the naked eye. Mars is a terrestrial planet with a thin atmosphere, with surface features reminiscent of the impact craters of the Moon and the valleys, deserts and polar ice caps of Earth.

The days and seasons are comparable to those of Earth, because the rotational period as well as the tilt of the rotational axis relative to the ecliptic plane are similar. Mars is the site of Olympus Mons, the largest volcano and highest known mountain on any planet in the Solar System and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan.

Mars has been explored by unmanned spacecraft. Mariner 4, launched by NASA on November 28, 1964, was the first spacecraft to visit Mars, making its closest approach to the planet on July 15, 1965. Mariner 4 detected the weak Martian radiation belt, measured at about 0.1% that of Earth and captured the first images of another planet from deep space. On July 20, 1976, Viking 1 performed the first successful landing on the Martian surface. The Soviet Mars 3 spacecraft achieved a soft landing in December 1971 but contact was lost with its lander seconds after touchdown. On July 4, 1997, the Mars Pathfinder spacecraft landed on Mars and on July 5 released its rover, Sojourner, the first robotic rover to operate on Mars. Pathfinder was followed by the Mars Exploration Rovers, Spirit and Opportunity, which landed on Mars in January 2004 and operated until March 22, 2010 and June 10, 2018, respectively. The Mars Express orbiter, the first European Space Agency spacecraft to visit Mars, arrived in orbit on December 25, 2003. On September 24, 2014, the Indian Space Research Organization became the fourth space agency to visit Mars, when its maiden interplanetary mission, the Mars Orbiter Mission spacecraft, arrived in orbit.

There are investigations assessing the past habitability of Mars, as well as the possibility of extant life. Astrobiology missions are planned, including the Perseverance and Rosalind Franklin rovers. Liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is less than 1% of the atmospheric pressure on Earth, except at the lowest elevations for short periods. The two polar ice caps appear to be made largely of water. The volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the planetary surface to a depth of 11 meters (36 ft). In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior.

Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.94, which is surpassed only by Venus, the Moon and the Sun. Optical ground-based telescopes are typically limited to resolving features about 300 kilometers (190 mi) across when Earth and Mars are closest because of Earth’s atmosphere. – Wikipedia

Explore Mars yourself with Google Mars: https://www.google.com/mars/

Screen shot of Valles Marineris in false color elevation mode in Google Mars.

Read more about Mars on NASA’s Solar System Exploration site: https://solarsystem.nasa.gov/planets/mars/overview/

OSIRIS-REx Asteroid Sample Return Mission

International Space Station

NASA Perseverance Mars Rover

Hubble Space Telescope

Kerbal Space Center adds female astronomer and computer scientist to staff

Margo does a lot of education and public outreach at the Kerbal Space Center; maybe we can get her to write a guest column for the Sacred Space Astronomy site! Seriously tho, KSP has been posting a lot of astronomy-related posts, and I just LOVE it!

Climate

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.

The Local Stellar Neighborhood

Continuing with my visual tour of nearby stars and their systems, we travel to YZ Ceti (Luyten 725-32), about 12 light years distant.

Distance to YZ Ceti (Luyten 725-32) from Sol; the plane (green) is aligned with the orientation of the plane of the Milky Way galaxy. Credit: SpaceEngine / Bob Trembley.

YZ Ceti

YZ Ceti is a red dwarf star in the constellation Cetus. Although it is relatively close to the Sun at just 12 light years, this star cannot be seen with the naked eye. It is classified as a flare star that undergoes intermittent fluctuations in luminosity. YZ Ceti is about 13 percent the mass of the Sun and 17% of its radius.

This star is unusually close to Tau Ceti, a star of spectral class G8. The two are only about 1.6 light years apart, a little more than a third of the distance from the Sun to the Solar System’s nearest neighbor, Proxima Centauri.

YZ Ceti is a variable star designation: the star shows occasional rapid and brief increases in brightness, sometimes reaching magnitude 12.03, caused by eruptions from the surface. This type of variable star is known as a UV Ceti star after its first member, or more colloquially as a flare star. It also shows small periodic variations in brightness caused by starspots or chromospheric features moving as the star rotates. This class of variable stars are known as BY Draconis variables. The periodic variations allow the rotational period of the star to be measured at 68.3 days, although modelling of its planetary system gives a rotational period for the star of 83 days.

On 10 August 2017 three planets were announced to have been discovered around YZ Ceti and a possible fourth sub-Earth planet candidate, still needing confirmation, with 0.472±0.096 Earth masses at an orbital period of 1.04 days. The orbits of the three confirmed planets were determined to be too close to YZ Ceti to be within the star’s habitable zone, with equilibrium temperatures ranging from 347–491 K (74–218 °C; 165–424 °F), 299–423 K (26–150 °C; 79–302 °F), and 260–368 K (−13–95 °C; 8–203 °F) for planets b, c, and d, respectively.

An August 2018 study reexamined the discovery measurements, confirming the orbit of YZ Ceti d, but finding a possibly marginally longer orbital period of YZ Ceti b of 2.02 days rather than 1.97 days, and additionally finding that YZ Ceti c probably orbits in only 0.75 days rather than 3.06 days. If the latter is true, YZ Ceti c would have a mass of only 0.58 Earth masses and a roughly 10% chance of transiting YZ Ceti. – Wikipedia

YZ Ceti System Architecture

YZ Ceti (Luyten 725-32) System Diagram. Note: exoplanet surface features are procedurally generated. Credit: SpaceEngine / Bob Trembley.

YZ Ceti Exoplanet Orbital Diagram

Top-down view of the exoplanet orbits around the red dwarf star YZ Ceti (Luyten 725-32). Credit: SpaceEngine / Bob Trembley.

Artist’s Rendering of Exoplanet YZ Ceti b

Artistic rendering of red dwarf star YZ Ceti seen from above the surface of exoplanet YZ Ceti b. Credit: SpaceEngine / Bob Trembley.

Artist’s Rendering of the Surface of Exoplanet YZ Ceti b

YZ Ceti b is likely tidally-locked to YZ Ceti – one face of the exoplanet always pointing towards the star. To get this screenshot, I landed on the exoplanet, and flew around its surface until I had the star where I wanted it on the horizon. I then accelerated time and waited for a cloud pattern I liked; it’s weird to watch the clouds flow past and the star just hangs there, unmoving.

“Perpetual Sunset on YZ Ceti b” Artistic rendering of red dwarf star YZ Ceti seen from the surface of exoplanet YZ Ceti b. Credit: SpaceEngine / Bob Trembley.

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