In the Sky This Week – September 25, 2018

Happy autumn! The autumnal equinox occurred on September 22^nd, this is when the Sun crosses the celestial equator, making the length of day and night approximately the same all over the Earth. With the onset of fall, the constellation Orion is now very high in the predawn sky

The constellation Orion high in the predawn sky on Sept. 25, 2018. Credit: Stellarium / Bob Trembley.

Jupiter will soon be leaving Mars and Saturn behind in the south-southwestern sky after dusk – catch it while you still can!

Mars, Saturn and Jupiter across the south-southwestern sky after sunset on Sept. 25, 2018. Credit: Stellarium / Bob Trembley.

Jupiter and Venus compete for the “evening star” title, but Jupiter will soon win, as Venus will no longer visible in the southwestern sky in a few short weeks.

Jupiter and Venus in the southwestern sky at dusk on Sept. 25, 2018. Credit: Stellarium / Bob Trembley.

The Moon

The Moon from Sep. 25-Oct. 1, 2018. Visualizations by Ernie Wright.

The Moon is a waning gibbous just after full; rising in the east at dusk, and setting in the west near dawn. The Moon will be near third quarter early next week, rising around midnight, and visible all morning.

The Moon appears in the south-southwestern predawn sky all week. Credit: Stellarium / Bob Trembley.

Observing Target: Mars

Mosaic of 102 Viking Orbiter images of Valles Marineris on Mars. Credit: NASA/JPL-Caltech

Now that the dust from the recent storm has settled, photographers are starting to get some great shots of Mars.

Mars, Sept. 21, 2018. Credit: User Viking 1 on the Cloudy Nights Forum.

You can always catch a glimpse of Mars from orbit from the VMC – Mars Webcam on the ESA Mars Express satellite.

You can interactively explore an elevation-map and satellite-view of Mars using Google’s Mars map.

Google Mars Elevation Map. Credit: NASA/JPL-Caltech/Arizona State University / Google

You can also interactively explore the surface of Mars (in ridiculously high detail) using NASA’s MarsTrek website.

NASA MarsTrek Close Up of Valles Marineris. Credit: NASA/JPL-Caltech.

In other news, engineers at JPL have been working over the past week to solve a communication issue with the Mars Curiosity rover.

The Sun

The Sun has been spot-free for 12 days. The gigantic coronal hole at the Sun’s north pole remains from last week, as does the smaller hole at the south pole; a very small hole seems to be fighting to form along the equator. The solar wind speed is 413.5 km/sec, with a density of 13.5 protons/cm³ – that’s higher than last week’s density – and THAT had been the highest density I’d seen in a while!

SpaceWeather.com says: “So far this year, the sun has been without sunspots for more than 154 days–including the last 12 days straight. To find a similar stretch of blank suns, you have to go back to 2009 when the sun was experiencing the deepest solar minimum in a century. Solar minimum has returned, bringing extra cosmic rays, long-lasting holes in the sun’s atmosphere, and strangely pink auroras.”

Some very nice, long-lasting prominences appear on the Sun’s limb – I’d love to set up my solar telescope and have a look, but it’s raining here in Michigan…

Asteroids

Upcoming Earth-asteroid encounters:

Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. Table from SpaceWeather.com

Near-Earth objects (NEOs) discovered this month: 165, this year: 1427, all time: 18828.
Potentially hazardous asteroids: 1923 (as of September 25, 2018)
Minor Planets discovered: 779,736 (as of July 31, 2018)

Fireballs

On Sept. 24, 2018, the NASA All Sky Fireball Network reported 7 fireballs.

In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. Source: Spaceweather.com

Comets

Comet 21P/Giacobini-Zinner is viewable in the eastern sky after midnight, and before dawn. The comet has moved considerably since last week, and is fading – catch a glimpse soon!

Location of Comet 21P/Giacobini-Zinner Sept. 25, 2018 4:00 AM. Credit: Stellarium / Bob Trembley.

Comet 21P/Giacobini-Zinner crossing M35. Credit: Keith Lisk.

The Solar System

This is the position of the planets and a couple spacecraft in the solar system:

Position of the planets and several spacecraft in the inner solar system, Sept. 25, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets in the middle solar system, Sept. 25, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Spacecraft

JAXA’s Hayabusa2 spacecraft made history this week – it is the first spacecraft to successfully land not one but TWO unique rovers onto the surface of an asteroid!

Asteroid fanatics (such as myself) and the NASA’s OSIRIS-REx mission are literally going crazy with excitement!

Exoplanets

Confirmed Exoplanets: 3,779 (9/6/2018)
Multi-Planet Systems: 626 (9/6/2018)
Kepler Candidate Exoplanets: 4,496 (8/31/2017)
TESS Candidate Exoplanets: 2
-Data from the NASA Exoplanet Archive

Researchers are starting to find exoplanet candidates in TESS data! I imagine this to be like that first little ball of snow, rolling down the mountain… right before starting an avalanche!

Latest Exoplanet Discoveries: https://exoplanets.nasa.gov

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.
Stellarium: a free open source planetarium app for PC/MAC/Linux. It’s a great tool for planning observing sessions.

2018 is NASA’s 60th Anniversary!