In the Sky This Week – December 11, 2018

Mercury joins Venus and Spica in the southeastern predawn sky this week.

Mercury, Venus and Spica in the eastern predawn sky – Dec. 11, 2018. Credit: Stellarium / Bob Trembley.

Mars remains high in southern sky after sunset all week; the Moon will appear near Mars on Dec. 14^th.

The Moon near Mars in the southern sky after sunset – Dec. 14, 2018. Credit: Stellarium / Bob Trembley.

See if you can spot all these objects in the south-southwestern sky at dusk on Dec. 11^th.

Mars high, Saturn low, Altair, Fomalhaut and the Moon at dusk – Dec. 11, 2018. Credit: Stellarium / Bob Trembley.

Observing Target: Fomalhaut

The star Fomalhaut (see above image) is one of the brightest stars in the sky; it is a main sequence class A star approximately 25 light-years from the Sun. In a small telescope, it looks pretty much like any another bright star – but this star has a story!

This image shows Fomalhaut, the star around which the newly discovered planet orbits. Fomalhaut is much hotter than our Sun, 15 times as bright, and lies 25 light-years from Earth. It is blazing through hydrogen at such a furious rate that it will burn out in only one billion years, 10% the lifespan of our star. The field of view is 2.7 x 2.9 degrees. Credit: NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

A ring of dust was discovered around this star, being shepherded by a large exoplanet with a 2000-year orbit! This exoplanet has be directly imaged using the Hubble Space Telescope.

Debris ring around Fomalhaut showing location of planet Fomalhaut b—imaged by Hubble Space Telescope’s coronagraph. (January 8, 2013) (NASA).

This humorous video about exoplanet Fomalhaut B was released before Halloween 2012:

The Moon

The Moon is a waxing crescent, visible toward the southwest in early evening. The Moon will be at first quarter on  Dec. 15^th, visible high in the southern sky in early evening. After Dec. 15^th, the Moon will be a waxing gibbous, visible to the southeast in early evening, up for most of the night.

The Moon from Dec. 11-17, 2018. Visualizations by Ernie Wright.

The Sun

We have a sunspot – a small one, and as of this writing an unnamed one… I did a bit of searching, but could not find who assigns the Active Region (AR) number to sunspots – so I asked:

Coronal holes remain open at both poles – the southern hole appearing much larger than the last few weeks. You can see a region of coronal activity slightly north of the equator where the sunspot is developing.

WOW! If you were lucky, you got to see one of the spectacular looping prominences that appeared on the Sun’s limb over the last couple days.

The solar wind speed is 516.4 km/sec (↑), with a density of 5.8 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: 18, this year: 1862, all time: 19261.
Potentially hazardous asteroids: 1936 (as of Nov. 20, 2018)
Minor Planets discovered: 789,069 (as of Oct. 30, 2018)

Fireballs

On Dec. 10, 2018, the NASA All Sky Fireball Network reported 33 fireballs.
(25 sporadics, 6 Geminids, 1 December Monocerotid, 1 sigma Hydrid)

In this diagram of the inner solar system, all of the fireball orbits from Dec. 10, 2018 intersect at a single point–Earth. Source: Spaceweather.com

Geminid Meteor Shower

Earth is entering the debris stream from comet 3200 Phaethon. Members of the International Meteor Organization report seeing more than 10 meteors per hour, rates that could increase 8-10-fold by Dec. 14th, when the shower is at its peak. The best time to see meteors is during the hours before dawn; Geminid meteors appear to radiate from the constellation Gemini is high in the sky. SpaceWeather.com photo gallery

Geminid meteor shower radiant. Credit: American Meteor Society.

[iframe src=”https://www.meteorshowers.org/view/iau-4″ width=”100%” height=”400″]

Comets

Comet 41P/Wirtanen being imaged by astrophotographer buddy Doug Bock, Dec. 10, 2018.

Wow Doug… there’s a LOT going on in all those windows!

The Solar System

This is the position of the planets and a couple spacecraft in the solar system; the Parker Solar Probe has recrossed the orbit of Venus.

Position of the planets in the inner solar system, Dec. 11, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Comet 67P/Churyumov–Gerasimenko is very near the planet Jupiter!

Position of the planets in the middle solar system, Dec. 11, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Very near Jupiter…

Comet 67P close pass to Jupiter 12-8-2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Spacecraft

OSIRIS-REx – Discovers Water on Asteroid Bennu!

Mars InSight – “Hears” Martian Wind!

Voyager 2 – Enters Interstellar Space!

-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!