In the Sky This Week – October 2, 2018

The Moon joins the constellations Gemini and Orion high south in the predawn sky.

The Moon near Orion and Gemini in the southeastern predawn sky on Oct. 2, 2018. Credit: Stellarium / Bob Trembley.

Mars and Saturn continue to be excellent observing targets in the southern sky after sunset.

Mars and Saturn southern sky after sunset on Oct. 2, 2018. Credit: Stellarium / Bob Trembley.

You might be able to catch a glimpse of Venus this week if you have a clear southwestern horizon; Venus is VERY low in the sky at sunset.

Jupiter and Venus in the southwestern sky at dusk on Oct. 2, 2018. Credit: Stellarium / Bob Trembley.

Observing Target: M45 – The Pleiades

The Pleiades (also known as the Seven Sisters) is an open star cluster located in the constellation of Taurus. The cluster contains several hot, B-type stars, and is among the nearest star clusters to Earth. The Pleiades easily visible to the naked eye – binoculars work great for viewing the Pleiades; if you want to use a telescope, you’ll need to use a longer focal-length (lower magnification) eyepiece.

The Pleiades through a small telescope (at low magnification), or binoculars. Credit: http://www.naasbeginners.co.uk

Time-exposures of the Pleiades reveal a blue nebulosity surrounding the stars; once thought to be left over from the formation of the cluster, it is now thought to be an unrelated cloud in the interstellar medium, through which the stars are currently passing.

The Pleiades open star cluster consists of approximately 3,000 stars. Credit: NASA, ESA, AURA/Caltech, Palomar Observatory The science team consists of: D. Soderblom and E. Nelan (STScI), F. Benedict and B. Arthur (U. Texas), and B. Jones (Lick Obs.)

The Pleiades rises around 10:00 PM in the east, and is high in the southern sky before sunrise.

Location of M45 – The Pleiades. Credit: Stellarium / Bob Trembley.

The Moon

The Moon is at third quarter on Oct. 2^nd, and will be a waning crescent the rest of the week. I always like this time in the Moon’s phase, because I can usually catch a glimpse of it through my kitchen window, just above my neighbor’s house, early in the morning.

The Moon from Oct. 2-8, 2018. Visualizations by Ernie Wright.

The Sun

The Sun has a spot! It’s small, and rotating out of view soon, but it’s the first spot to show up in a while!

The sunspot has some nice coronal loop activity, seen as the bright region in the animation below. The gigantic coronal hole at the Sun’s north pole seems to have gotten even larger; the smaller hole at the south pole appears to have almost completely vanished. Solar wind is streaming out of two coronal holes along the Sun’s equator.

SpaceWeather.com says: “Two holes in the sun’s atmosphere are turning to face Earth, each spewing a stream of solar wind toward our planet. Estimated times of arrival: Oct. 4th and Oct 7th. Solar wind spewing from the smaller hole (right) will arrive first, causing polar geomagnetic unrest but probably not a full-fledged geomagnetic storm. Solar wind escaping from the second, larger hole (left) will follow days later bringing a chance of G1-class storms. In both cases, equinox cracks in Earth’s magnetic field will permit the solar wind to spark Arctic auroras.”

The solar wind speed is 477.4 km/sec, with a density of 5.9 protons/cm3 – a bit slower, and much less dense than last week.

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

A few long-lived prominences continue appear along the Sun’s limb, with several shorter-lived ones popping up all over; it’s still 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 Oct. 1, 2018, the NASA All Sky Fireball Network reported 18 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:

Position of the planets and several spacecraft in the inner solar system, Oct. 2, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets in the middle solar system, Oct. 2, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Spacecraft

Last week, I mentioned the unique asteroid rovers that the JAXA’s Hayabusa2 spacecraft successfully landed on asteroid Ryugu – here are images from that asteroid’s surface!

The Parker Solar Probe does a gravity-assist flyby of Venus on Oct. 3!

Exoplanets

Confirmed Exoplanets: 3,791 (9/27/2018)
Multi-Planet Systems: 629 (9/27/2018)
Kepler Candidate Exoplanets: 4,717 (8/16/2018 – 8/31/2017 was 4496, that’s quite a jump!)
TESS Candidate Exoplanets: 2
-Data from the NASA Exoplanet Archive
Latest Exoplanet Discoveries: https://exoplanets.nasa.gov

World Space Seek: Oct. 4-10

Since its United Nations declaration in 1999, World Space Week has grown into the largest public space event on Earth. More than 3,700 events in 80 countries celebrated the benefits of space and excitement about space exploration in 2017.  The 2018 theme is “Space Unites The World” and 2019 theme “The Moon:  Gateway to the Stars.”

“The General Assembly declares 4 to 10 October World Space Week to celebrate each year at the international level the contributions of space science and technology to the betterment of the human condition”

– UN General Assembly resolution, 6 December 1999

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!