Science. Education. Community. Fun.

Looking Up

April 2020

Even with the “shelter-in-place” rules in place, you can still go outside and take in the sky. Hopefully the temps (and the clouds) will allow for that. Let’s start off talking about Venus in the western evening sky. Venus reached its greatest separation from the Sun late last month (March 24) and, as it comes a bit closer to the Earth, its set time doesn’t change much this month. It pretty much sets at 11:30pm. Now since it is getting darker later, Venus sets 4 hours after the Sun in early April and then 3.5 hours at month’s end. The distance to Venus goes from 0.65 to 0.44 astronomical units and the planet brightens a bit to magnitude -4.7. Through the telescope, it becomes more of a crescent and appears larger. Can you see the crescent phase in binoculars? Do use those binocs on the evening of April 3 to see Venus in the heart of the Pleiades star cluster. In fact, start looking on April 1 and watch the planet’s movement through the cluster. The Moon is to the left of Venus on April 26th. Next month, Venus will appear much lower in the sky and it will pass between the Sun and Earth at the end of May.
In the morning sky, we still find Mars, Saturn, and Jupiter in the southeast before dawn. Jupiter appears the brightest of the three with Saturn in the middle of the trio. Mars and Saturn are roughly the same brightness. On the 10th, the three will appear roughly the same distance apart and in close to a straight line. The last quarter Moon cruises by the trio on the mornings of the 14th through the 16th, as shown below in the image.
There’s other “stuff” happening this month, too. The Lyrid Me-teor Shower peaks during the early morning hours of April 22nd. The meteors result from the leftover dust of Comet Thatcher and observations date back to 687 BC! During a normal year, one might see 20 meteors per hour, but it is noted that there have been several years of outburst. They saw five times as many meteors per hour in 1982. This is New Moon time, too, so the skies will be dark. Why not have a look?
Next, if you’re up for it, why not look for the asteroid Juno, which reaches opposition on April 2. At magnitude 9.5 you have to have a pretty dark sky and good binoculars to even have a chance at it, but a telescope should work nicely. From April 9-13 the asteroid passes just south (0.5 degrees) of the 3.3 magni-tude star, Delta Virginia (“Minelauva”). Maybe look on several nights and see if you can detect movement of a star-like object.
Lastly, have you heard the hype surrounding Comet ATLAS (C/2019 Y4), discovered last December by an automated survey instrument in Hawaii? It’s apparently brightening and its coma (gas cloud surrounding the nucleus) is about half the width of the Sun! At its distance, this comes out to an apparent size of 15 arc minutes. Keep in mind the nucleus itself is still probably a few kilometers across. The diatomic carbon in the comet gives it a greenish hue. Keep in mind comet brightness is very unpre-dictable but, if it “behaves,” ATLAS is expected to brighten from magnitude 11.5 to 7.8 by the end of April. Perihelion occurs on May 31 at a distance of 23.5 million miles from the Sun and it will be closest to Earth two days before this at 72 million miles. Predictions put the max brightness anywhere from +2 to -11! IF you want to look for the comet, it can be found between the North Star and Capella in the north-northwest. For finder charts see: http://www.cometwatch.co.uk/comet-atlas-could-reach-naked-eye-brightness/
I miss observing the sky with all of you. Astronomy is fun in groups and, as this issue is distributed, we’re not being encour-aged to do that. Keep in mind that, despite our open house(s) being canceled, you can still use the observatory site but please practice safe social dis-tancing. I hope to catch you out there soon when there are no restrictions. Be safe and healthy.
-DCL

March 2020
Have you notice Venus appearing out of the blue sky much clos-er to due west? And it’s about as high as you’ll see it, too, and it brightens a bit this month. The planet reaches its greatest separation from the Sun on the 24th of this month at 46 degrees. That’s nearly five fists held at arm’s length! It sets a good four hours after sunset, too! Through the telescope Venus is roughly half-lit. By the end of next month, you’ll start to see Venus low-er with each sunset. While you’re at the telescope, Venus pass-es the planet Uranus on the evening of March 7, “missing” it by 2.2 degrees with Uranus being to the southeast. A thin cres-cent Moon is below Venus on the evening of the 27th and to the left of the planet on the 28th. If you’re talking visible planets, that’s about it for the evening sky.
It’ll be worth setting the alarm for some pre-dawn skywatching this month as Mars catches and laps both Jupiter and Saturn in March. We begin the month with the three planets situated just east of the Teapot of Sagittarius, with Mars rising about 3:30am. Jupiter is about 10 degrees (one fist) to the east and Saturn fol-lows by 8 degrees. As we proceed through the month, Mars gets closer to Jupiter. The waning crescent Moon enters the picture on the morning of the 17th, to the right of the trio. On the morning of the 18th, the Moon is immediately below Mars and Jupiter (pictured here) who are them-selves only 1.5 degrees apart. On the 20th, the planets are separated a scant 0.7 degrees. The Moon then moves off to the east each morn-ing and, on the morn-ings of the 25th and 26th, Mars is between Jupiter and Saturn. Finally, Mars comes to within 0.9 degrees of Saturn on the morning of the 31st. Make a mental note of the sep-aration of Jupiter and Saturn; they end the month about 6.5 de-grees apart. Morning twilight begins at 5am at the beginning of March and just after 4am at the end if you want to catch the planets in a dark sky.
While all this is going on, Mercury is also in the morning sky, though must closer to the horizon. Though Mercury is above the horizon for many days, its altitude isn’t that impressive. Greatest separation from the Sun occurs on the morning of the 24th but, even at that time, it rises at 5am, only an hour before the Sun. Use Jupiter, Saturn and Mars as an arrow to point at where Mercury would be located near the horizon.
The March full Moon or “Worm Moon” is said to be the largest of the year. A “Supermoon!” Those who read this column reg-ularly know how I feel about supermoons! I guess if it gets the public interested in looking at the sky, it’s all good. But the Moon is 6% larger than an average Moon and the public doesn’t notice the difference. Any object, whether it be the Moon or even an entire constellation appears larger near the horizon due to the “Moon illusion.” Google that if you’re interested. I al-ways tell people who see a “large” Moon near the horizon to hold out a fist at arm’s length and extend your pinky finger. Close one eye and you can cover the Moon with only this finger. Many won’t believe that until you try it. So . . . try it!
The long-awaited vernal equinox occurs on the evening of March 19 at 10:50pm. At this time the Sun is directly above the Earth’s equator. Have you noticed the daylight hours increas-ing? They should be roughly 50/50 after mid-March. Let’s hope this year’s open house season transcends last year . . . which should be easy to do as I think we had one really nice clear night last year!
DCL

 

February 2020

We have probably the best evening view of the planet Mercury this month, at least until June. The month begins with Mercury far below and a bit to the right of Venus. Greatest separation from the Sun occurs on February 10 when Mercury sets at the same time twilight ends, about 90 minutes after sunset. The point is, don’t wait on the sky to get dark as Mercury will be gone. By around February 22, Mercury will be tough to see as it heads back towards the Sun. Again, use Venus as your guide. Venus seems to get higher in the sky this month as is it bright-ens. It will also seem to move closer to due west with respect to the horizon. Telescopically, Venus will appear to get closer and closer to what we’d call a first quarter Moon shape as we go through the month.

The rest of the action is in the morning sky where you can find Mars, Jupiter and Saturn. Mars leads the trio, rising just after 3:30am in mid-February. Look low in the southeast. Jupiter appears about an hour after that and Saturn not quite an hour after that. With Mars moving faster than the other two, it will catch and pass the two gas giant planets next month. The Moon creeps up on the three planets on the 18th. In fact, look for the waning crescent Moon to “occult” (pass in front of) Mars at about 6am on the morning of the 18th (pictured). Check it out with binoculars. When the Moon occults a star, the star blinks out. This was one of the first bits of evidence for the Moon not having an atmosphere (something we take for granted today). Mars, not appearing like a pin-point source, will fade out instead of blink out. The next day (morning of the 19th), the Moon is thinner and to the right of Jupiter and, early on the 20th, it is below and right of Saturn. The Moon will then pass through the new phase to be just left of Venus on the evening of the 27th. That will look cool! Photo-op! If you get a good photo, send it to me and we’ll publish it!

If you have those binoculars out, the Moon will clip the Hyades star cluster (marking the face of Taurus, the Bull) on the evening of February 3rd. The Hyades are an open cluster and the closest open cluster to us at 153 light years.

Have you seen Comet PanSTARRS T2 yet? It is hovering around the Double Cluster in Perseus at the beginning on the month, but will seem to turn northward to be near Epsilon Cassiopeia by early March. Comets can fluctuate in brightness so be alert. Who knows how bright it will be, but the predictions are that it will begin the month at magnitude 9.5 and it brightens to 8.8 by the end of the month. Report what you see!

Have you heard that Betelgeuse is fading as the shoulder of Orion the Hunter? Betelgeuse is a known variable star, so this could very well be the natural cycle of the star. Some claim the red giant star may be going supernova. It could happen! And then again, it could happen 100,000 years in the future, too! Might be good to keep an eye on Betelgeuse and compare its brightness to Rigel, to the lower right of the three belt stars.

DCL