In the Sky This Week – July 24, 2018

Mars opposition happens this week; several people told me recently that they’ve seen Mars in the southwestern sky during the early morning hours. I find myself looking for Mars almost automatically now.

Mars, bright in the south-southwestern sky at 5:00 AM on July 24, 2018. Credit: Stellarium / Bob Trembley.

Jupiter, Saturn, Venus and the Moon make sidewalk astronomy almost too easy for the next few days.

Venus low in the western sky after sunset, July 24, 2018. Inset: Venus’ current phase. Credit: Stellarium / Bob Trembley.

A friend and I set up our telescopes on a small hill, along a busy road in Calumet Michigan. We had a couple families with children show up and they got to see them all! We got some stunned “WOWs!” – those are always nice. The half-Venus was easy to see in the ‘scopes!

Astronomy Outreach on Fireman’s Memorial Hill – with Eric Jones in Calumet MI July 23, 2018. Credit: Bob Trembley

The Moon

The Moon is a waxing gibbous, visible in the southeastern before sky before dusk, and is visible all night long. The Moon will be full on July 27^th, after which it will be a waning gibbous, visible in the southeastern sky after sunset.

The Moon from July 24-30, 2018. Visualizations by Ernie Wright

The Moon will appear VERY near to Saturn on July 24^th.

The first quarter Moon near Saturn, and Jupiter in the southern sky at 10:00 PM, July 24 2018. Credit: Stellarium / Bob Trembley.

The Moon will appear near to Mars on July 27^th, which also happens to the the day of the Mars opposition.

The Moon near Mars in the southern sky at midnight on July 27, 2018. Credit: Stellarium / Bob Trembley.

There will be a total lunar eclipse on 27^th; North America will be unable to view this eclipse:

Visibility of the total lunar eclipse on July 27, 2018. Credit: NASA/Fred Espanak

Observing Target: Saturn

Saturn’s rotational axis is angled such that its rings are tilted towards us; the planet is just beautiful in telescopes. This is a great time to show Saturn to first-time telescope users!

Saturn, as it appears in a small telescope. Credit: Bob Trembley / Stellarium

You can see quite a bit more when you look at Saturn using the Hubble Space Telescope!

Saturn from the Hubble Space Telescope. Image credit: NASA, ESA and Erich Karkoschka (University of Arizona)

But the absolute best way to view Saturn is with an orbiting spacecraft… like the Cassini Spacecraft, which orbited Saturn from 2004-2017 collecting science data and hundreds of thousands of images.

Saturn’s rings display their subtle colors in this view captured on Aug. 22, 2009, by NASA’s Cassini spacecraft. The particles that make up the rings range in size from smaller than a grain of sand to as large as mountains, and are mostly made of water ice. The exact nature of the material responsible for bestowing color on the rings remains a matter of intense debate among scientists. Image Credit: NASA/JPL-Caltech/Space Science Institute

Browse the Cassini Mission archive of Saturn images here: https://saturn.jpl.nasa.gov/galleries/images/

The Cassini mission to Saturn ended in September of 2017; NASA has been nominated for an Emmy award for this farewell to Cassini video:

The Sun

Spaceweather.com says the Sun as been spot-free for 2 days – I’m not sure what reset the count from last week’s 20; I haven’t noticed any spots (honestly, I haven’t been looking that hard this week), but there was that very active region rotating out of view last week… maybe that had something to do with it.

There are coronal holes at both poles, and an odd, elongated set of holes reaching towards the equator, and almost forming an island. The solar wind speed is 578.5 km/sec… WOW! … with a density of 6.9 protons/cm³.

SpaceWeather.com says: “NOAA forecasters say there is a 65% chance of minor G1-class geomagnetic storms today, July 24th, when a stream of solar wind is expected to hit Earth’s magnetic field. The gaseous material is flowing from a broad hole in the sun’s atmosphere. Solar wind speeds are expected to exceed 600 km/s, based on reporting from NASA’s STEREO-A spacecraft, which encountered the stream before Earth did.”

It looks like there were lot of small prominences on the Sun yesterday… but when I took my new solar telescope out after an afternoon lecture, I could not spot any of them.

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: 75, this year: 966, all time: 18516.
Potentially hazardous asteroids: 1912 (as of July 24, 2018)
Minor Planets discovered: 779,736 (as of July 24, 2018)

Fireballs

On July 24, 2018, the NASA All Sky Fireball Network reported 12 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 in the inner solar system – days away from Mars opposition – July 24, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.

Exoplanets

Confirmed Exoplanets: 3,774 (7/19/2018)
Multi-Planet Systems: 625 (7/19/2018 )
Kepler Candidate Exoplanets: 4,496 (8/31/2017)
TESS Candidate Exoplanets: 0
Data from the NASA Exoplanet Archive

Apps used for this post:

Stellarium: a free open source planetarium app for PC/MAC/Linux. It’s a great tool for planning observing sessions.
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.

2018 is NASA’s 60th anniversary!