In the Sky This Week – December 18, 2018

Venus shines so brightly in the southeastern predawn sky, you can practically read by it! Jupiter makes its reappearance this week, joining Mercury, Venus and the star Spica.

Jupiter, Mercury, Venus and Spica in the eastern predawn sky – Dec. 18, 2018. Credit: Stellarium / Bob Trembley.

Mars is high in southern sky after sunset all week; the waxing gibbous Moon appears to the east of Mars on Dec. 18^th.

The Moon and Mars high in the south-southeastern sky after sunset – Dec. 18, 2018. Credit: Stellarium / Bob Trembley.

The star Altair is now the “evening star” to the west at dusk; Saturn has almost vanished into the glare of the Sun.

Saturn very low in the southwestern sky at dusk on Dec. 18, 2018. Credit: Stellarium / Bob Trembley.

The Moon appears very near the star Aldebaran high in the western sky around 3:30 AM on Dec. 21st.

The Moon very near the star Aldebaran at 3:35 AM on Dec. 21, 2018. Credit: Stellarium / Bob Trembley.

On Christmas Eve, the waning gibbous Moon will appear in the eastern sky after sunset.

The Moon hight in the eastern sky near midnight on Dec. 24, 2018. Credit: Stellarium / Bob Trembley.

Observing Target: M1 – The Crab Nebula

M1, the Crab Nebula, is a supernova remnant located in the constellation of Taurus. The supernova was so bright in 1054 that it could be seen during the day for nearly a month; the supernova was documented by astronomers in several countries.

X-Ray: Chandra	Ultraviolet: ASTRO-1	Visible: DSS	Visible: Color VLT
Near-Infrared: 2MASS	Mid-Infrared: Spitzer	Far-Infrared: IRAS	Radio: NRAO

Images from http://coolcosmos.ipac.caltech.edu/cosmic_classroom/multiwavelength_astronomy/multiwavelength_museum/m1.html

Location of M1 – the Crab Nebula. Credit: Stellarium / Bob Trembley.

The Moon

The Moon is a waxing gibbous – visible to the southeast in early evening, up for most of the night. The full Moon occurs on Dec. 22^nd – rising at sunset, high in the sky around midnight, and visible all night. After the 22nd, the Moon will be a waning gibbous – rising after sunset, high in the sky after midnight, visible to the southwest after sunrise.

The Moon from Dec. 18-24, 2018. Visualizations by Ernie Wright.

The Sun

A bright region of coronal loop activity appears near the Sun’s equator, but no sunspot is associated with it; the Sun as been spot-free for 2 days. Large coronal holes continue to remain open at both poles.

SpaceWeather.com says “The solar cycle is at low ebb. Today marks the 208th day in 2018 that the sun has been without spots, doubling the number of spotless days in 2017. The count won’t be able to double again in 2019; there aren’t enough days in the year! However, we can expect a further deepening of Solar Minimum in the year ahead with, literally, hundreds of spotless days to come.”

Several small prominences have appeared on the Sun’s limb over the last couple days – one loop (lower right) and several short-lived pillars, but no “OH WOWs” like happened last week.

The solar wind speed is 411.4 km/sec (↓), with a density of 6.5 protons/cm³ (↑).

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

Near-Earth objects (NEOs) discovered this month: 85, this year: 1929, all time: 19328.
Potentially hazardous asteroids: 1936 (as of Nov. 20, 2018)
Minor Planets discovered: 789,069 (as of Oct. 30, 2018)

Fireballs

On Dec. 17, 2018, the NASA All Sky Fireball Network reported 14 fireballs.
(9 sporadics, 2 Quadrantids, 2 sigma Hydrids, 1 Comae Berenicid)

In this diagram of the inner solar system, all of the fireball orbits from Dec. 17, 2018 intersect at a single point–Earth. Source: Spaceweather.com

https://twitter.com/UKMeteorNetwork/status/1074603747815407616

Comets

Comet 46P/Wirtanen made its closest approach to Earth on Dec. 17^th. Social media has been flooded with images.

The Solar System

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

Position of the planets in the inner solar system, Dec. 18, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets in the middle solar system, Dec. 18, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Comet 67P/Churyumov–Gerasimenko continues it’s slow crawl by the planet Jupiter!

Comet 67P/Churyumov–Gerasimenko near Jupiter, Dec. 18, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Check out NASA’s Interactive Solar System Orrery at: https://solarsystem.nasa.gov – click on the animated Orrery icon to launch the browser app.

It’s kinda like NASA Eyes on the Solar System LITE, but for the browser; it can be used on computers where you cannot install the full Eyes client app.

Note: The Orrery is a WebGL browser app, and its performance is better on systems with hardware-accelerated graphics.

Spacecraft

OSIRIS-REx – Maneuvering around Asteroid Bennu

Mars InSight – Prepares to Deploy Seismometer

Parker Solar Probe – Views the Sun’s Corona Closer than any Spacecraft Before!

Dec. 24th is 50th Anniversary of Apollo 8 Orbiting the Moon!
Launched on December 21, 1968, Apollo 8 became the first piloted spacecraft to leave low Earth orbit, reach the Moon, orbit it, and return safely to Earth.

Recreation of the iconic “Earthrise” image taken by Apollo 8’s William Anders, using image data from the Lunar Reconnaissance Orbiter (LRO), with an added model of the Apollo 8 spacecraft. Visualization by Ernie Wright.

-Data from the NASA Exoplanet Archive

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!