Sun

One quick one before the sky.

NASA's Parker Solar Probe has reported in after its 29th close approach to the Sun, which it made on the 4th of September.

Still holding the record?

Still holding it, and that's now the eighth time it has.

Completely.

The encounter ran from the 30th of August to the 9th of September, and for nine days of that, it's on its own with no contact.

Too close to the Sun to talk.

It sent a beacon tone on the 7th to say it was healthy.

From Earth, places like the National Solar Observatory in Sunspot, New Mexico, can document fluctuating activity and monitor changes over time at our superstar.

But where can you watch the sun all day and all night? Let's go to space.

From the studios of Cincinnati Public Radio, I'm your host Dean Regas, and this is Looking Up.

Another mission called STEREO, short for the Solar Terrestrial Relations Observatory...

Hmm, yeah, that's a little bit of a acronym stretch for me, but-

STEREO, it's a mission to help us understand what we call space weather, how the activity on the Sun can affect us here at Earth.

This launched twin satellites in 2006 in opposite directions into space.

One craft, Stereo A, left Earth in a path around the Sun, while the other, Stereo B, headed off in the other direction, also around the Sun.

In five years.

In five years, around an object that takes 63 years to go round the Sun.

That's the finding.

These are not static structures you can photograph once and file away.

Which is closer than it'll be when it's actually in orbit.

Closer than the science orbit, which is the point the team keeps making.

And at the exact moment it was down there, the Sun let go of a major eruption of energetic particles.

The lead author, Kilpua, at the University of Helsinki, puts it plainly, "The fourth flyby was unique.

itself.And that gives you the famous line, mass and energy tell space-time how to curve, and the curvature of space-time tells objects how to move.

The Earth isn't being pulled toward the Sun by an invisible rope.

The Sun's mass warps space-time into a deep indentation, and Earth just follows the straightest possible path through that curved landscape.

Like a marble rolling around a bowling ball on a stretched rubber sheet.

The marble isn't being pulled by anything.

And this makes real predictions.

Light has no mass, but it should still bend because it follows the curvature of space-time.

The Sun acts like a gravitational lens.

Il che significa che qualunque cosa accada, la Terra non cancellerà mai del tutto ogni nostra traccia.

Non finché il Sole non si trasformerà nella sua fase di gigante rossa tra circa cinque miliardi di anni.

E anche allora è possibile che qualche resto dell'umanità, un osso delle dita o un dente, magari il vostro, rimanga sepolto nel profondo della superficie fino agli ultimi giorni del nostro pianeta.

Ma questa è una storia per un altro: cosa succederebbe se? [musica di chiusura]

With Venus this bright, some people go looking for it in daylight, which is a real and rewarding thing to do, and also the one time of year we get nervous.

Venus in daylight sits close to the Sun in the sky.

Never sweep for it with binoculars or a telescope without a proper solar filter fitted at the front.

A fraction of a second of direct sunlight through magnifying optics causes permanent, painless retinal damage.

If you're looking anywhere near the Sun with your eyes alone, use eclipse glasses certified to ISO 12312-2.

Check them for scratches or pinholes first, and understand what they're for.

They are made for the naked eye only, and must never be used in combination with binoculars, a telescope, or a camera viewfinder.

The safe way to find Venus in daylight is to use a solid object, a building edge, a wall, to block the Sun completely before you start looking.

This deduction, which can be tested with great accuracy, has been confirmed for all the planets save one, with the precision that is capable of being obtained by the delicacy of observation attainable at the present time.

The sole exception is Mercury, the planet which lies nearest the Sun.

Since the time of Le Verrier it has been known that the eclipse corresponding to the orbit of Mercury, after it has been corrected for the influences mentioned above, is not stationary with respect to the fixed stars, but that it rotates exceedingly slowly in the plane of the orbit and in the sense of the orbital motion.

The value obtained for this rotary movement of the orbital ellipse was 43 seconds of arc per century, an amount ensured to be correct to within a few seconds of arc.

This effect can be explained by means of classical mechanics only on the assumption of hypotheses which have little probability, and which were devised solely for this purpose.

On the basis of the general theory of relativity, it is found that the ellipse of every planet round the Sun must necessarily rotate in the manner indicated above, that for all the planets, with the exception of Mercury, this rotation is too small to be detected with the delicacy of observation possible at the present time, but that in the case of Mercury it must amount to 43 seconds of arc per century, a result which is strictly in agreement with observation.

Apart from this one, It has hitherto been possible to make only two deductions from the theory which admit of being tested by observation.

To wit, the curvature of light rays by the gravitational field of the sun, first observed by Eddington and others in 1919, and a displacement of the spectral lines of light reaching us from large stars, as compared with the corresponding lines for light produced in an analogous manner terrestrially, i.e. by the same kind of atom, established by Adams in 1924.

Let's begin with the order of the planets.

Starting from the Sun, we have Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

So Mercury is first, and Venus is second.

Exactly.

Mercury is about 58 million kilometers from the Sun, while Venus is about 108 million kilometers away.

That means Mercury is much closer.

Shouldn't it receive more heat?

Why is it called a greenhouse gas?