In the Sky This Week – October 23, 2018

The constellations Leo and Ursa Major appear in the east-northeastern sky before sunrise; the bright star Regulus is hard to miss in the eastern sky.

The Constellations Leo and Ursa Major (including the “Big Dipper” asterism) are in the east-northeast predawn sky. Credit: Stellarium / Bob Trembley.

The constellations Orion and Taurus are high in the southwestern predawn sky.

The constellations Orion and Taurus are high in the southwestern sky before dawn. Credit: Stellarium / Bob Trembley.

Mars and Saturn are great observing targets this week; sadly, Saturn is getting lower in the southwestern sky each evening.

Mars high and Saturn a bit lower in the south-southern sky after sunset on Oct. 23, 2018. Credit: Stellarium / Bob Trembley.

The full and waning gibbous Moon will be visible nearly all night long this week – rising later in the east with each evening.

Position of the Moon in the early morning hours over the week of Oct. 23-29, 2018. Credit: Stellarium/ Bob Trembley

Jupiter and Mercury appear low in the southwestern sky at dusk – Mercury may be quite the challenge to see.

Jupiter and Mercury low in the southwestern sky at dusk on Oct. 23, 2018. Credit: Stellarium / Bob Trembley.

Observing Target: Conjunction of the Moon and Aldebaran

There will be an early morning conjunction of the Moon and the star Aldebaran on Oct. 27^th.

Early morning conjunction of the Moon and the star Aldebaran in the constellation Taurus at 6:00 AM on Oct. 27, 2018; the Pleiades star cluster is nearby. Credit: Stellarium/ Bob Trembley

Comets

Appearing wider than the planet Jupiter, comet 46P/Wirtanen continues to make the news:

Comet 46P Wirtanen – Oct. 18, 2018. Credit: Rolando Ligustri

You can find Comet 46P/Wirtanen low in the southern sky after midnight this week – the Moon may wash it out quite a bit this week, tho…

Position of Comet 46P/Wirtanen Week of Oct. 23-29 2018. Credit: Stellarium/ Bob Trembley

Position of Comet 46P/ Wirtanen in the Solar System, Oct. 23, 2018. Credit: JPL Small Body Database / Bob Trembley

The Moon

The Moon is a waxing gibbous heading towards full on the 24^th; for the rest of the week the Moon will be a waning gibbous. The Moon will visible all night long earlier this week, and well past dawn later in the week.

The Moon from Oct. 23-29, 2018. Visualizations by Ernie Wright.

The Sun

The sun has been spot-free for 5 days. The coronal hole that reopened at the south pole last week remains open, but is small compared to the several weeks-old north polar coronal hole; a couple small coronal holes appear near the equator – SpaceWeather.com says “Solar wind flowing from this large coronal hole could reach Earth on Oct. 24^th.” Something with a lot of coronal loop activity is rotating out of view on the Sun’s limb.

As seems to be the case with this solar minimum, there are a couple relatively long-lasting prominences on the Sun’s limb, and several small ones popping up and quickly disappearing. 

The solar wind speed is 314.2 km/sec, with a density of 2.5 protons/cm³ – light and mild right now… let’s see what the 24^th brings…

Animated LASCO C2 Coronograph showing the solar corona above the Sun’s limb (the white circle).

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

2018 UA above was listed as passing at 0 Lunar Diameters – that seemed pretty close, so I looked it up – it passed within about 75,000 km:

Position of asteroid 2018 UA Oct. 19, 2018. Credit: JPL Small Body Database / Bob Trembley

Near-Earth objects (NEOs) discovered this month: 141, this year: 1602, all time: 19000.
Potentially hazardous asteroids: 1936 (as of October 23, 2018)
Minor Planets discovered: 785,045 (as of October 9, 2018)

Fireballs

On Oct. 22, 2018, the NASA All Sky Fireball Network reported 45 fireballs.

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

The Solar System

This is the position of the planets and a couple spacecraft in the solar system – the Parker Solar Probe is almost to the orbit of Mercury, and Mars InSight is continues to close-in on Mars.

Position of the planets and several spacecraft in the inner solar system, Oct. 23, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets in the middle solar system, Oct. 23, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Inferior Conjunction of Venus

On Oct. 26th, Venus will pass almost directly between Earth and the Sun – this is known as an “Inferior Conjunction.” As the conjunction approaches, the nighttime side of Venus is turned towards the Earth, and only a … thin sliver of the planet is visible.

Venus, Oct. 20, 2018. Credit: Shahrin Ahmad

Spacecraft

Repair Work on Hubble Continues

Mars InSight CubeSat Attendant Spots Mars

OSIRIS-REx Update

Exoplanets

Confirmed Exoplanets: 3,798 (10/11/2018)
Multi-Planet Systems: 630 (10/11/2018)
Kepler Candidate Exoplanets: 4,717 (8/16/2018)
TESS Candidate Exoplanets: 44
-Data from the NASA Exoplanet Archive
Latest Exoplanet Discoveries: https://exoplanets.nasa.gov

Solar Week: Oct. 22-26

Solar Week is a week of online lessons, games and hands-on activities about the Sun for grades 5-9 or ages 9-14. Solar Week happens twice a year, approximately mid-to-late March and mid-to-late October.

Monday – The Sun As a Star
Tuesday – Solar Close-Ups
Wednesday- The Active Sun
Thursday – The Sky Above: Earth’s Upper Atmosphere
Friday – Solar Careers, Internships and Opportunities

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!