As I mentioned last week, Jupiter was at opposition on Friday, April 7 – this means it’s opposite the sun, from our perspective, making it at its most “full” (though, as I’ve pointed out before, the outer planets are always very close to full from our vantage point).  It’s also on the same side of the solar system as us, and we’re passing it… so opposition is also our closest approach on this orbit.

As is typically the case, a lot of media outlets picked up on these items and broadcast as the best/brightest/superlative day to see Jupiter all year, as if it were suddenly huge!  I have to concede it was technically the closest approach, but it was not necessarily something you’d notice.  In fact, on this particular pass we’re actually farther away than most, just given the eccentricity (non circular-ness) of our orbits.  So instead of feeling like we’ve missed out by not camping out all night Friday, I like to look at opposition as the opening of the evening viewing window.  Jupiter now rises before sunset, and we’ll have lots of summer evenings to comfortably see the gas giant.

In fact, go take a look on Monday, April 10.  The full moon (at its opposition!) will be right next to Jupiter, and the bright star Spica, in Virgo, is nearby (generally below).  As you look at the Moon-Jupiter pairing, consider the relative distances – Jupiter is 40 times larger in diameter than the Moon, and 1700 times farther away.  Spica, meanwhile, is 70 to 80 times larger than Jupiter, and 3.7 million times farther away.  In this one glimpse, you’re seeing our closest neighbor, our largest planet, and many light-years into the distance (and our past), and there are some monstrous objects out there!

Jupiter aside, as I promised way back in February, the comet scene is heating up with some unexpectedly brightening targets.

1. 41P/T-G-K is still out there in Draco, between the dippers.  It can still be seen in binoculars, but it never achieved the peak brightness that was hoped.  I’m still proud I got a picture of it, though!
2. Comet C/2017 E4 Lovejoy, which as you recall was just discovered a month ago, on March 10, has been brightening considerably and is now an early morning target in Pegasus – right now passing the star marking the northeast corner of the Great Square, and passing near the Andromeda Galaxy between April 20-22.  This comet is growing a faint narrow tail, headed for perihelion in late April, and its orbit is almost 90-degrees off the ecliptic (the orbital plane of the planets).  If you can picture this, it has come up through the planetary disk, will whip around the “top” of the sun, and then dive back down.  It should be visible in binoculars for a few weeks to come.
3. The newest target – C/2015 ER61 Pan-STARRS was off the viewing radar, until suddenly late last week it increased dramatically in brightness.  Some sort of gas eruption or landslide on the comet caused fresh plumes, or exposed bright ice to the sun, or…  we don’t really know, but what was a very faint afterthought is now a binocular comet, and it’s pretty close to Lovejoy – you can see both on the same morning.  Pan-STARRS is low on the horizon at dawn, about 10 degrees up, in Aquarius.  So it might be harder to find even though it is bright.  Its movement almost exactly opposes the westward drift of the constellations, so it will show up in the same spot, at the same time, for a while, even as the star patterns behind it change.

For both Lovejoy and Pan-STARRS, try and see them early in the week if you want to try, otherwise you’ll have a bright gibbous moon spoiling the darkness.  I may plan some early mornings to try and catch them, since I’m figuring out my photo-stacking techniques!  These two comets in particular, and their changes over the past few weeks, are good reminders that space is a pretty dynamic place, things are always changing, and sometimes in unexpected ways!

Last but not least, a teaser.  The Lyrid meteor shower is coming… April 22, early morning will be the best time.  It is a moderate meteor shower that typically peaks in the range of 10-20 meteors per hour, but always pretty.  More on that to come, next week!

Get Out There!

Troy

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