In the Sky This Week – September 24, 2019

Saturn and Jupiter continue to make excellent observing targets after sunset all week.

Saturn, Jupiter and the star Antares in the south-southwestern sky at 9:00 PM this week. Credit: Stellarium / Bob Trembley.

A recent tweet from the Hubble Space Telescope shows Saturn’s rings in all their glory! I got a chance to see Saturn through a large telescope recently – the Cassini Division was clearly visible.

By midnight, Saturn is near to setting in the southwestern sky, and star Fomalhaut is high in the southern sky.

Saturn and the star Fomalhaut in the south-southwestern sky at midnight this week. Credit: Stellarium / Bob Trembley.

The constellation Orion is high in the southern sky before sunrise; I saw it this morning as my wife drove off to work – it’s impossible to miss above the roof of my house!

The constellation Orion is high in the southern sky before sunrise. Credit: Stellarium / Bob Trembley

The Moon will be between the stars Regulus and Algieba before sunrise on September 26^th – if you’re up, be sure to look for earthshine! (Note: the Moon is shown magnified for better visualization.)

Conjunction of the waning crescent Moon and the star Regulus – 6:00 AM Sep. 26th. Credit: Stellarium / Bob Trembley

The Constellation Ursa Major

Ursa Major is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means “greater she-bear,” referring to and contrasting it with nearby Ursa Minor, the lesser bear. Wikipedia

My wife and I having our first meeting of our after-school club, the Endeavour Space Academy, this week. We’re going to concentrate on observing this year, and getting to know the night sky – I want students to be able to see and identify objects in the early evening sky (before it gets too late for them…); we’re starting with something everyone in the northern hemisphere has already seen, but may not have known they’ve seen: the constellation Ursa Major, and it’s right there to the north after sunset.

Constellation Ursa Major (with lines shown) in the North-northwestern sky at 9:00 PM on Sep. 24th. Credit: Stellarium / Bob Trembley

Most people will be familiar with “the Big Dipper” – which is an asterism – a pattern of stars that is not a constellation. The two farthest stars in Dipper’s bowl can be used as a “star-hopping” guide the the north star, Polaris; I actually found myself doing this very thing the other evening without thinking about it!

Big Dipper Asterism of constellation Ursa Major with star-hopping guide (red) to Polaris, the north star at 9:00 PM on Sep. 24th. Credit: Stellarium / Bob Trembley

Western sky art for the constellation Ursa Major:

Constellation Ursa Major at 9:00 PM on Sep. 24th with Western sky art shown. Credit: Stellarium / Bob Trembley

Arabic sky art for the constellation Ursa Major:

Constellation Ursa Major at 9:00 PM on Sep. 24th with Arabic sky art shown. Credit: Stellarium / Bob Trembley

Ursa Major is host to numerous deep-sky objects (DSO); if I cranked up the number of visible DSO markers all the way up in Stellarium, this image would be filled with red and orange markers!

Major deep-sky objects in constellation Ursa Major. Credit: Stellarium / Bob Trembley

The human eye is really a pretty terrible tool for doing astronomy… it can not perceive infrared, so we’re missing out on seeing the clouds of gas and dust that our Sun is drifting through:

Constellation Ursa Major at 9:00 PM on Sep. 24th seen in far infrared from the AKARI Far-Infrared All-Sky Survey. Color composition: (blue: N60; green: WideS; red: WideL). AKARI FIS All-Sky Survey HEALPIX map produced by the Centre d’Analyse de Donees Etendues (CADE) with the original processed data from ISAS/JAXA. See http://www.ir.isas.jaxa.jp/AKARI/Archive/Images/FIS_AllSkyMap/Doi_AKARI_FIR_AllSkySurvey.pdf
Source: Stellarium, Edited by: Bob Trembley

Sometimes I get asked “Why is the sky dark?” I respond with “It’s NOT! You just can’t see all the different light pouring down on you!” If you could see microwaves, the sky would be glowing in all directions from the Cosmic Microwave Background Radiation (CMB).

Cosmic Microwave Background Radiation around the constellation Ursa Major from the the Planck mission – PLANCK R2 LFI color composition – 30-44-70 GHz.
The Planck mission will collect and characterise radiation from the Cosmic Microwave Background (CMB) using sensitive radio receivers operating at extremely low temperatures. These receivers will determine the black body equivalent temperature of the background radiation and will be capable of distinguishing temperature variations of about one microkelvin. These measurements will be used to produce the best ever maps of anisotropies in the CMB radiation field.
Source: Stellarium, edited by: Bob Trembley

The Moon is a waning crescent, visible low to the east before sunrise – my favorite in the morning with coffee! Both my wife and I saw it with bright earthshine this morning.

The new Moon occurs on  September 28^nd, deep-sky photographers rejoice!

After September 28^nd, the Moon will be a waxing crescent, visible toward the southwest in early evening; more opportunity to see earthshine!

The Moon from Sep. 24-30, 2019. Visualizations by Ernie Wright / NASA’s Scientific Visualization Studio.

I was rather pleased with how well SpaceEngine simulated earthshine on the waxing crescent Moon early next week:

Simulation of earthshine on the waxing crescent Moon seen from space above South America – Sep. 30, 2019. Credit: SpaceEngine / Bob Trembley

Moon News

https://twitter.com/JimBridenstine/status/1176228748317904897

The Sun has been spot-free for 21 days; the northern coronal hole remains huge, the southern hole is all but closed, and a monster coronal is on the equator, facing right at us!

Sun in 193 angstroms (extreme ultraviolet) Sept. 24, 2019. Image courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.

[Link to 48-hour video of the Sun in 193 angstroms]

One really large prominence recently, and several smaller ones over the last couple days

Sun in 304 angstroms (extreme ultraviolet) Sept. 24, 2019. Image courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.

[Link to 48-hour video of the Sun in 304 angstroms]

https://www.facebook.com/photo.php?fbid=478316509685135&set=gm.2669665689711425&type=3&theater&ifg=1

The solar wind speed is 451.4 km/sec (↑), with a density of 606 protons/cm³ (↑) at 2106 UT.

Animated LASCO C2 Coronograph showing the solar corona above the Sun’s limb (the white circle). Credit: NASA/JPL-Caltech

Sun News

Upcoming Earth-asteroid encounters:

Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. Red highlighted entries are asteroids that either pass very close, or very large with high relative velocities to the Earth. Table from SpaceWeather.com

On Sep.24, 2019, the NASA All Sky Fireball Network reported 56 fireballs.
(55 sporadics, 1 southern Taurid)

In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). From: Spaceweather.com

Fireball News

Comet C/2019 Q4

https://twitter.com/Mars_1956/status/1174819139556433923

Position of the planets and a couple bodies in the inner solar system:

Position of the planets and some spacecraft in the inner solar system, Sep. 24, 2019. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets and a couple bodies in the middle solar system:

Position of the planets in the middle solar system, Sep. 24, 2019. Credit: NASA Eyes on the Solar System / Bob Trembley.

Position of the planets and a couple bodies in the outer solar system, with the orbit of dwarf planet Eris highlighted:

Position of the planets in the outer solar system, Sep. 24, 2019. Credit: NASA Eyes on the Solar System / Bob Trembley.

Dwarf planet Eris has a Moon: Dysnomia.

Artist’s conception of dwarf planet Eris seen from above its moon Dysnomia. Credit: SpaceEngine / Bob Trembley

I used SpaceEngine to land on Dysnomia and look at Eris on the horizon:

Artist’s conception of dwarf planet Eris seen from the surface of its moon Dysnomia. Credit: SpaceEngine / Bob Trembley

Dysnomia orbits Eris with an eccentricity of < 0.013 - not quite but almost circular; Earth’s Moon has an eccentricity of 0.0549. Dysnomia’s orbit around Eris is inclined to the solar system’s plane of the ecliptic.

NASA’s Interactive Real-Time Web-based Orrery:

[iframe src=’https://eyes.nasa.gov/apps/orrery/’ height=600 percent=100 style=””]

Solar System News – International